octupus manual

See Also:

� Definition Heading� Definition Motions� Definition Statistical Operators� Definition of Phase� Definition of Wavespectra

See Also:

� Definition Coordinate System� Definition Motions� Definition Statistical Operators� Definition of Phase� Definition of Wavespectra� Envelopes sea state statistics

AmarconOCTOPUS Office 6.0

Amarcon OCTOPUS Office Manual includes the following information:

� Definitions� Introduction Octopus Office� User Guide� Quick Guide

© 2007 Amarcon B.V.All rights reserved. No portion of the contents of this publication may be reproduced or transmitted in any form or by any means without the express written permission of Amarcon B.V.

For more information on OCTOPUS Office, see http://www.amarcon.com

Definition Coordinate System

All the coordinates are defined relative to a coordinate system with:

� x-axis pointing to bow � y-axis pointing to Portside � z-axis pointing upward

� Origin x=0 at APP (Aft Perpendicular) � Origin y=0 at CL (Centerline) � Origin z=0 at BL (Baseline)

� surge: x-axis positive direction � sway: y-axis positive direction � heave: z-axis positive direction � roll: positive portside up/starboard side down � pitch: positive bow down/stern up � yaw: positive bow to port/stern to starboard side

Definition Heading

There are two definitions for directions in OCTOPUS-Office. In general all directions are relative to the vessel. But in case of performing a voyage analysis all directions are relative to north.

In general all headings are defined relative to the vessel. The direction of approaching waves is in this case 180 degrees.

An exception is made in W3C Calculation, where the directions of waves are relative to north.

of 56

15.02.2012file:///C:/Users/octopusoffice/AppData/Local/Temp/~hh292B.htm

See Also:

� Definition Coordinate System� Definition Heading� Definition Motions� Definition of Phase� Definition of Wavespectra

Definition Statistical Operators

In the statistical analyses it is assumed that the responses are linear or Gaussian, and that the extremes follow a Rayleigh probability distribution. From this the following relations can be derived:

Spectral moments:

The spectral moments of the responses are the basis Spectral moments of the responses are calculated as follows:

Where is the response spectrum, omega the radian frequency and beta the wave direction. A special case is m0 which is the spectral moment or variance of the response.

Zero-upcrossing period.The zero-upcrossing period is defined as the:

Significant single amplitudeThe significant amplitude of a response is given by:

Significant double amplitudeThe significant double amplitude of a response is given by:

MaximumThe maximum is defined as the Most Probable Extreme (MPE), given by

wher t is the reference period of a sea state, in seconds, typically 3 hours or 10400 seconds. This reference period can be defined by the user.

Rayleigh distributionThe probability density of the amplitudes, a, and its cumulative probability (or probability distribution) follow the Rayleigh density and distribution. This can be written as:

Definition Motion

The definiton of the motion follows from the definition of waves:Figure 1 shows a harmonic wave as seen from two different perspectives. Figure a shows what one would observe in a snapshot photo made looking at the side of a (transparent) wave flume; the wave profile is shown as a function of distance x along the flume at a fixed instant in time. Figure b shows a time record of the water level observed at one location along the flume; it looks similar in many ways to the other figure, but time t has replaced x on the horizontal axis.

Figure 1: Harmonic wave definitions

Notice that the origin of the co-ordinate system is at the still water level with the positive z-axis directed upwards; most relevant values of z will be negative.The still water level is the average water level or the level of the water if no waves were present. The x-axis is positive in the direction of wave propagation. The water depth, h, (a positive value) is measured between the seabed (z = -h) and the still water level (z = 0).The highest point of the wave is called its crest and the lowest point on its surface is the trough. If the wave is described by a harmonic wave, then its amplitude is the distance from the still water level to the crest, or to the trough for that matter. The subscript a denotes the amplitude, here.

The horizontal distance (measured in the direction of wave propagation) between any two successive wave crests is the wavelength, . The distance along the

time axis is the wave period, T. The ratio of wave height to wavelength is often referred to as the dimensionless wave steepness:

Since the distance between any two corresponding points on successive harmonic waves is the same, wave lengths and periods are usually actually measured

of 56


See Also:

� Definition Coordinate System� Definition Statistical Operators� Definition Heading� Definition of Phase� Definition of Wavespectra� RAO Responses

between two consecutive upward (or downward) crossings of the still water level. Such points are also called zero-crossings, and are easier to detect in a wave record. Since sine or cosine waves are expressed in terms of angular arguments, the wavelength and wave period are converted to angles using:

in which k is the wave number (rad/m) and is the circular wave frequency (rad/s).

Obviously, the wave form moves one wave length during one period, so that its speed or phase velocity, c, is given by:

Suppose now a sailing ship in waves, with co-ordinate systems as given in figure 2.

Figure 2: Co-ordinate systems

A right-handed co-ordinate system S(x0, y0, z0) is fixed in space. The (x0,y0)-plane lies in the still water surface, x0 is directed as the wave propagation and z0 is directed upwards.

Another right-handed co-ordinate system O(x,y,z) is moving forward with a constant ship speed V. The directions of the axes are: x in the direction of the forward ship speed V, y in the lateral port side direction and z vertically upwards. The ship is supposed to carry out oscillations around this moving O(x,y,z) co-ordinate system. The origin O lies vertically above or under the time-averaged position of the centre of gravity G. The (x,y)-plane lies in the still water surface.

A third right-handed co-ordinate system G(xb,yb,zb) is connected to the ship with its origin at G, the ship's centre of gravity. The directions of the axes are: xb in the longitudinal forward direction, yb in the lateral port side direction and zb upwards. In still water, the (xb,yb)-plane is parallel to the still water surface.

If the wave moves in the positive x0-direction (defined in a direction with an angle relative to the ship's speed vector, V), the wave profile - the form of the water surface - can now be expressed as a function of both x0 and t as follows:

The right-handed co-ordinate system O(x,y,z) is moving with the ship's speed V, which yields:

From the relation between the frequency of encounter and the wave frequency : follows:

The resulting six ship motions in the O(x,y,z) system are defined by three translations of the ship's centre of gravity in the direction of the x-, y- and z-axes and three rotations about them:

The phase shifts of these motions are related to the harmonic wave elevation at the origin of the O(x,y,z) system, i.e. the average position of the ship's centre of gravity:

The harmonic velocities and accelerations in the O(x,y,z) system are found now by taking the derivatives of the displacements, for instance for surge:

The motions of the motion reference point as entered in RAO Responses are transformed from the calculated motions in the O(x,y,z) plane. The phase shifts of these motions are related to the harmonic wave elevation at this motion reference point entered in RAO Responses.

of 56


See Also:

� Definition Coordinate System� Definition Motions� Definition Statistical Operators� Definition of Heading� Definition of Wavespectra� Envelopes sea state statistics

Definition of Phase

The motions are defined in the following way:

The calculated six ship motions are defined by three translations of the motion reference point (in the picture above chosen as center of gravity) in the x, y and z axis and three rotations about them:

In which the subscript "a" denotes the response amplitude and epsilon denotes the phase shift. The phase shifts of these motions are related to the harmonic wave elevation at the motion reference point:

The phase shift of the roll motion with respect to the wave elevation, in the figure above is positive, because when the wave elevation passes zero at a certain instant, the roll motion already has passed zero. Thus, if the motion comes before the wave elevation, then the phase shift is defined as positive.

Definition of Spectra and Spreading

Different spectra are available to define a sea state, the following can be used:

� Bretschneider (equals Pierson-Moskowitz), which gives a an average wave spectrum, frequently used in open sea areas� Jonswap, which is a narrow wave spectrum, frequently used in North Sea areas. Jonswap has an extra parameter, gamma, which defines the steepness of

the spectrum. This parameter is not used in the definition of the Neumann and Bretschneider spectra. When gamma is selected as value 1, it gives the same spectrum as the Pierson-Moskowitz spectrum

� Neumann, this gives a somewhat wide wave spectrum, which is sometimes used for open sea areas

A comparison of the Neumann, the Bretschneider and the mean JONSWAP wave spectra is given here for a sea state with a significant wave height of 4 meters and an average wave period of 8 seconds.

of 56


See Also:

� Definition Coordinate System� Definition Statistical Operators� Definition Heading� Definition of Phase� Definition of Motion

The spectrum spreading is defined as a cosinen function, where n is the number entered at 'Spreading', a value of 2 generally meets the conditions concerning wind waves, and 8 meets conditions concerning swell. The reason why spreading has been introduced is due the short crestedness of the waves. A short crestedness is characterized by a two dimensional wave spectrum, which is written as:

For example when the spreading is 2, f(chi) is defined as:

Swell has a lower spreading, so it is nescessary to define a higher value for n in order to get the correct representation.

For more information about the different wave spectra, see the 'OCTOPUS Seaway Theory' on www.amarcon.com/support and select documentation

Introduction Octopus Office.

Because of the complexity and value of marine transports and operations at sea, it is not only required but also beneficial to carry out dedicated motion analyses. The results of such an analysis are primarily required during the transport preparation phase, from quotation to the design and engineering of the stowage plan, cribbing and sea fastenings.

Traditionally, marine transports are engineered to satisfy design criteria in terms of allowable wave heights. The 'Allowable wave height' can be calculated as the 'Allowable response level' divided by the 'Response level per unit wave height'. It follows that different responses may result in different allowable wave heights, depending on the allowable response level.

It is obvious that the allowable wave height also depends on the other wave parameters, like the wave period, spectrum shape and spreading.

Operational parameters like the vessel heading and vessel speed may have a large effect on the response level in a certain sea state, and thus on the allowable wave height. The same applies for the vessel's voyage plan. That's why weather routing is commonly applied. In general favorable wave headings for roll are unfavorable headings for pitch and the related accelerations. Detailed knowledge about the vessel's seakeeping behavior makes it possible to do more advanced weather routing, namely by evaluating and optimizing for ship responses in the forecasted weather (=waves).

In fact we are not talking about one allowable wave height, but about many allowable response levels. Each allowable response level implies a related allowable wave height, which again may depend on wave heading etc. This results in a "minimum allowable wave height". A balanced design of for example sea fastenings should therefore be based on the calculation of the expected levels of the relevant responses in the most likely wave environment.

The analysis sequence as applied in Octopus Office is shown in Figure 1. The obtained design values may serve as the criteria which should not be exceeded during the transport or operation. The calculated models and design values can be used in Octopus Onboardgive onboard operational support using the same methods and results as used in design value calculation procedure.

of 56


See Also:

� Definition Coordinate System

Create New Project

OCTOPUS-OFFICE 6 Modules.

OCTOPUS-OFFICE 6 is available in different modules, depending on the license:

OCTOPUS-OFFICE 6 "BASIC"

OCTOUS-OFFICE 6 "BASIC" is used to calculate the transfer functions of ship responses in waves (absolute and relative motions, velocities, accelerations, hull girder loads and linear combinations of responses).

The program has a built-in geometry-modeler to prepare 2D- and 3D-models as input for the hydrodynamic calculations (2D-strip theory or a 3D-diffraction database can be used). Nonlinear sea state dependent transfer functions are solved by means of stochastic linearization. The program features extensive possibilities for graphical and textual reporting and presentation, including export functions to MS Word and Excel.

EXTENSION "STATISTICS"

The extension "STATISTICS" is used to calculate short- and long-term response statistics in arbitrary wave environments; including environment modeling tools (from single parametric sea state to fully-directional wave spectra; editable route- or site-specific scatter diagrams, multi-directional seas).Single response statistics (most probable maxima, significant values, out-crossing statistics, etc), envelope curves or workability in scatter diagrams is just a selection of the quantities that can be analyzed.

EXTENSION "W3C"

More elaborate voyage-specific seakeeping analyses can be carried out when time series of waves are available. Using spectral data instead of derived wave parameters such as significant wave height, mean direction or zero-upcrossing period, ensures more accurate results, especially in multi-directional seas. Moreover, persistency effects are automatically included.

Using "W3C" voyage simulations can be carried out by using the Argoss w3c-database (www.argoss.nl). This historical world-wide wave database is the product of satellite observations and a 3rd generation wave model. It covers a period of 15 years with a time resolution of 3 hours. The wave condition at a particular date, time and location is described by a distribution of the energy, the direction and the directionality, as a function of the frequency. The position list of an indicative voyage can be used as input for voyage simulations. The simulations are carried out for different dates and time of departure, and repeated until convergence is obtained after 'N' simulations.

Introduction to the User Guide

The User Guide contains the following information:

� Explanation of the different items.

1. Start OCTOPUS Office2. To create a new project, click File, New...

� Type a new name at 'Project Name'.Because OCTOPUS Office registers projects by name, use a unique name for each project.

� Type a new description at 'Project Description'. � 'Location' specifies the directory where the new project is located.

Type a path or select one by using the browse button to the right of the 'Location' box.

of 56


See Also:

� Open Existing Project� Using the Workspace

Open Existing Project

See Also:

� Create New Project� Using the Workspace

Using the Workspace

3. Click OK to create the project.

1. Start OCTOPUS Office2a. To open an existing project, click File and select Open.... 2b. It is also possible to open a recent project from the Recent File List under File.

The OCTOPUS Office workspace has two areas as shown in the picture below:

The left area is used to display the project tree, the right area is used to hold the openend documents.The project tree consists of calculation results done by the user and one folder with common used files such as Voyages, Sea States and Scatter Diagrams.

Open the items in the left area by right mouse click.

The selected item in the right plane is marked bold in the left plane.

An item becomes red if the conditions for a calculation have been changed. In that case the calculation has to be redone and saved again before the item becomes black again.

2D Hull Modeller

To open the 2D Hull Modeller, click Tools, 2D Hull Modeller...

of 56


See Also:

� 3D Hull Modeller� Create 2D CHDB

A set of hulls is available within Ocopus Office under File, Open..., then select a hull you want to use. After saving the used hull under a different file name it is possible to scale the main dimensions of the hull.To edit the number of frames or the shape (offsets) of the frames, click Edit,...

The hull file can also be saved in a normalized hull file, click File, Save Normalized Hull File as..A normalized hull file is made non-dimensional, in such a way that it has a length, a breadth and a draught of 1.00 meter. Then - to obtain its actual dimensions again - these normalised hull forms are resized by using the numerical values of L, B and T as scale factors at the end of the hull form data file.

3D Hull Modeller

To open the 3D Hull Modeller, click Tools, 3D Hull Modeller...

To create a CHDB-file it is required to create a grid file, too. This can be done with the 3D Hull Modeller: Below the steps are described which are needed to create a grid file (*.glv)

� Open the hull file, click File, Open and select the *.hul file. � Create a mesh, click Geometry, Mesh. The following dialog appears:

of 56


See Also:

� 2D Hull Modeller� Create 2D CHDB

� 'Draft Aft': Insert draft Aft � 'Draft Foreward': Insert draft Foreward � 'Baseline': Insert the position of the baseline in the coordinate system in which the hull file is specified. For the Amarcon hull files this is 0. � 'No. Parts Longitudinal': Insert the required number of parts � 'No. Parts Girthwise': Insert the required number of parts � Click button OK to create the mesh.

� Check if the (0,0,0) position is equal to (APP,CL,BL). If so, Save the mesh as a *.glv file: Click File, Save as.. and save the file as *.glv file.If the (0,0,0) position is not equal to (APP,CL,BL), use the translate function to translate the origin to the required location. Click Geometry, Translate.

To view the hull: � Left mouse pressed and move the mouse to change the position of the hull. � Right mouse pressed and move the mouse to rotate the hull. � Left and Right mouse pressed and move the mouse to zoom in or out.

Create 2d CHDB (Compiled Hydrodynamic Database)

To create a 2D- CHDB, click Tools, Create 2D CHDB...A Hull (*.hul) and Grid (*.glv) file should be available. These files can be created with 2D Hull Modeller and 3D Hull Modeller

� 'Hull file' specifies the location of the hull file. To select a location, click button Browse. The Hull Browser is opened, within the Hull Brwoser one gets a view of the hull. Click again button Browse in the Hull Browser to select a different location. Finally click button Open in the Hull Browser.

� 'Grid file' specifies the location of the grid file. � 'Name' Type the name of the vessel and eventually a description. � 'Waterdepth' Specifies the waterdepth for which the CHDB will be calculated. � 'X-position of 0-point relative to APP' Specifies the longitudinal position which is the reference point for wave forces calculation. The phase of a wave

is then calculated with respect to this point. � 'Minimum wave frequency' and 'Maximum wave frequency' The mimimum and maximum values of the wavefrequencies are calculated automatically

according to parameters obtained from the hull file, but can also be entered manually. � 'No. of wave frequencies' Enter the number of wavefrequencies that are desired for the CHDB calculation. The amount of frequencies is an indication

for the accuracy of the calculations, a value of 40 is recommended here. � 'Solution method' Select the required solution method. Each method has its own specific range of application and benefits.

Lewis and Ursell-Tasai can be used for ordinary hull forms (recommended for most calculations) Frank is applicable for normal hullforms with more complicated hull sections, such as bulbous bows Keil is also applicable for calculations concerning shallow water It is recommended to see the 'Octopus Seaway Theory' at www.amarcon.com/support/documentation for more information about the diferent methods, too.

� 'CHDB file' type the name and the location of the CHDB file which will be created after clicking button Create.

To change the Draft Settings select the Draft tab. See the figure below. To define a range of drafts change 'No. of Drafts', 'Minimum Draft' and 'Maximum Draft" and click on Use. It is also possible to edit a range of draft values manually by using Insert, Remove and Remove all.Default the mimimum and maximum draft value are calculated from the hull file.

of 56


See Also:

� Introduction CHDB� Add CHDB� 2D Hull Modeller� 3D Hull Modeller

See Also:

� Wave Scatter from database� Wave Scatter Grid Settings� Definition of different wave spectra

(The settings for Speeds and Headings are managed in the same way as for Drafts)

Introduction Common

Under ‘Common’ data is stored is not related to one particular ship. This (statistical) data is specifically aimed at describing the wave environment. Either by means of a voyage, which can be matched in space and time with a wave climate database, or by a scatter diagram, or simply a set of design sea states.

Wave Scatter diagram

Browse in the project tree to 'Scatter Diagrams' (via Common) Create a new scatter diagram by a right mouse click, then Create and type the name of the new scatter diagramAdd an existing scatter diagram by a right mouse click, then Add and browse to the existing scatter diagram

A wave scatter diagram shows the probability of a wave combination of Hs and Tz. The scatter diagram is used for statiscal analysis, it can be created in two different ways. The scatter diagram can be created in different ways:- Manually, by entering number of incident waves in the particular grid field. - From different databases, click Scatter DB see Wave Scatter from database

When editing the scatterdiagram manually, the following spectra definitions are available:- Neumann- Bretschneider (equals Pierson-Moskowitz)- Jonswap

The spectrum spreading is defined as a cosinen function, where n is the number entered at 'Spreading', A value of 2 generally meets the conditions concerning wind waves, and 8 meets conditions concerning swell.

To change the settings of the grid go to Settings.... Be careful though, changing the grid settings will clear the actual scatter diagram automatically! see Wave Scatter Grid Settings

Wave Scatter Grid Settings.

To change the grid settings for Hs and Tz, enter the required numbers in the particular fields. Be carefull, changing the grid settings will clear the actual scatter diagram!

of 56


See Also:

� Wave Scatter Diagram

See Also:

� Wave Scatter Diagram� Wave Scatter from GWS database� Create a Voyage� Settings Design Seastate

Get scatter data from database.

To select data from a scatter database:

� Select the required Scatter Database in the field 'Scatter database' � Select a voyage or select areas manually in the map. (select multiple areas by holding the <ctrl> key pressed)

When a voyage is selected, the hours spend in the different areas are calculated automatically. When necessary, the hours can be adjusted. The Design Seastate (Hs) is calculated for each area with a given seastate height threshold and chance of exceedance.These settings are described in Settings Design Seastate

Get scatter data from Global Wave Statistics database.

The Global Wave Statistics Database contains long term scatter diagrams per area. For each area the season and direction can be given to get the corresponding scatter diagram. To select data from a GWS scatter database:

� Select the option "GWS" in the field 'Scatter database'. � Select a voyage or select areas manually in the map. (select multiple areas by holding the <ctrl> key pressed). � Change the estimated time of departure if needed and press the button <Update> to recalculate the whole voyage

of 56


See Also:

When a voyage is selected, the following items will be filled in for each area autmatically:

� The hours spend in the each area that will be passed during the voyage. When necessary, the hours can be adjusted. � The season when passing the area. When necessary the season can be changed. � The direction will always be set to "0.0 to 360". So that all waves from all directions will be used. When necessary the direction can be changed. � Design seastate(Hs) will be calculated for each area with a given seastate height threshold and chance of exceedance. These settings are described in

Settings Design Seastate.

When necessary the season can be changed by clicking on the season field in the grid. A pull-down menu will show all the available seasons for this area.Select a new season and the scatter diagram will be recalculated.

When necessary the direction can be changed by clicking on the direction field in the grid. A pull-down menu will show all the available directions for this area.Select a new direction and the scatter diagram will be recalculated.

of 56


� Wave Scatter Diagram� Wave Scatter from database� Create a Voyage� Settings Design Seastate

See Also:

� Wave Scatter Diagram

See Also:

� Define Range of Sea States� Import Sea States� Definition of different wave spectra

Wave Scatter Design Seastate Settings.

This window contains two different settings:

� Setting for the location of the BMT Global Wave Statistics Database � Settings for calculating the Design seastate for each area during a voyage

Sea States.

Browse in the project tree to 'Sea States' (via Common) Add an existing sea state by right mouse click Add and browse to the existing sea state.Create a new sea state by right mouse click Create and type the name of the new sea state. After that the following dialog appears.

A sea state can be generated in two different ways: 1. By entering numbers manually 2. Or by generating a range of sea states by clicking button Define Sea States.

A sea state consists 1 or 2 wave systems, where the second wave system is defined with an angle with respect to the first wave system. Typically, 2 wave systems are used when a combination of sea and swell should by applied.

The spectrum spreading is defined as a cosinen function, where n is the number entered at 'Spreading', A value of 2 generally meets the conditions concerning wind waves, and 8 meets conditions concerning swell.

Different spectra are implemented:

� Bretschneider (equals Pierson-Moskowitz)� Jonswap � Neumann

The period definition is either Peak Period (Tp) or Zero Crossing Period (Tz)

Define Range of Sea States.

of 56


See Also:

� Sea States� Import Sea States� Definition of different wave spectra

See Also:

� Sea States� Define Range of Sea States

See Also:

� Wave Scatter from database

The range of sea states can be generated for:

� Constant Steepness � Constant wave height � Constant wave height according to Noble Denton Definition

The gamma value is only applicable when using the Jonswap wave spectrum. The minimum and maximum wave periods are calculated automatically according to parameters related to the Noble Denton Definition. This definition gives the following relation between waveheight and period.

These minimum and maximum waveperiods can also be edited manually.

Import Sea States

To import a sea states file:

� Right click at 'Sea States' in the tree at Common. � Choose Import from the menu.

� Type the name of the sea states file. � Browse to a 3rd party sea states file. � Select the type of decoder. � Click OK

Voyages

A voyage is created by clicking on a specific location while holding the <ctrl> key pressed. Once a waypoint is generated its position can be changed by changing the values in the fields 'Latitude' and 'Longitude' manually.

Assign a specific port to a waypoint by clicking button Port List.Change the layout of the map by clicking 'Map Options'.

Enter tab 'Track' in the Map Options screen to change the default values for the voyage.The speed at a specific waypoint can also be changed manually by changing the number in field 'Speed (kn)'

The Estimated Time of Departure can be entered by clicking on the date column of the first Waypoint.

Change the date and time of departure. Press on OK and the whole voyage will recalculated with the new start date.

of 56


See Also:

� Introduction to CHDB� Create 2D CHDB� 2D Hull Modeller� 3D Hull Modeller� Add CHDB

See Also:

� Create CHDB� View CHDB

Introduction Compiled Hydrodynamic Database (CHDB)

In OCTOPUS, a hydrodynamic analysis starts with the calculation of a hydrodynamic database (HDB). The hydrodynamic database does not depend on parameters like ship mass, viscous damping or spring restoring parameters. These become important when RAO's are calculated.

This extensive hydrodynamic database contains all the relevant hydrodynamic properties of the vessel for a range of drafts, speeds, headings and frequencies. After calculation of the hydrodynamic database the database file contains:

� A definition of the geometry (3D) � Radiation pressure distributions for the six modes of motion � Diffraction pressure distributions for all wave headings.

A hydrodynamic database can be calculated in 2D or 3D:

� The 2D hydrodynamic database can be calculated using Octopus Office. This is done with the 2D strip theory. The strip theory solves the three-dimensional problem of the hydromechanical and exciting wave forces and moments on the ship by dividing the ship into several 'strips'. The 3D-solution is the obtained by integrating the two-dimensional potential solutions over the ship's length. Interactions between the cross sections are ignored for the zero-speed case.The strip theory is designed to calculate the hydrodynamic parameters for slender bodies. However, experiments showed that the strip theory appears to be remarkably effective for predicting the motions of ships with length to breadth ratios (L/B) down to about 3.0, and sometimes even lower.

� The 3D hydrodynamic database can be calculated using any 3rd-party 3D radiation/diffraction program. This is not a part of Octopus Office, but Amarcon is able to deliver a 3D CHDB for ships and offshore structures. 3D-panel methods tend to be better in predicting hydromechanical parameters.

Create CHDB (Compiled Hydrodynamic Database)

A 2D- CHDB file can be created within Octopus Office.To create a 2D- CHDB, an Hull and Grid file should be available. The hull file can be created with the 2D Hull Modeller.The grid file can be created with the 3D Hull Modeller.The 2D-CHDB file can be created with 2D CHDB Creator.

The 3D hydrodynamic database can be calculated using any 3rd-party 3D radiation/diffraction program. This is not a part of Octopus Office, but Amarcon is able to deliver a 3D CHDB for ships and offshore structures.

Add CHDB (Compiled Hydrodynamic Database).

To add a chdb right click at the top of the project tree.The following window appears:

'Name': type the name which will appear in the project tree.

After clicking OK select the required CHDB file in the following window by clicking the Browse button:

View CHDB (Compiled Hydrodynamic Database).

Once the CHDB is added, the properties of the vessel are shown in different tabs. Be carefull when selecting another CHDB file, the calculations which are located below in the tree (left pane) have to be calculated again!

of 56


See Also:

� Add CHDB� Introduction to HDB

See Also:

� View CHDB

General properties like drafts, speeds, directions and frequencies for which the CHDB is valid are shown in the tab 'General'Trans X, Trans Y and Trans Z specifies the position which is the reference point for wave forces calculation. Phase of a wave is the phase with respect to this point.

� Tab Geometry� Tab Wave Forces� Tab Added Mass & Damping� Tab Motion Equation Coefficients

Geometry.

The properties of the geometry are shown.

The properties of the geometry can be viewed for the different drafts by clicking in the cell displaying the draft. A list is shown with the different drafts in the file from where a selection can be made.

Wave Forces.

The Response Amplitude Operator (RAO) of the wave loads is shown in a colormap.

of 56


See Also:

� View CHDB

See Also:

� View CHDB

By left click and drag in the colormap the heading for the diagrams displayed at the right of the colormap can be changed.Right click in the colormap or diagrams gives the following options:

� Copy to Clipboard (puts figure in clipboard) � Show Cursor � Full Screen � Settings..., which can be used to change z-axis scale

By clicking button the numerical values are displayed in a table. Right click in the table copies the numerical values to the clipboard. Clicking button displays the diagrams again.

Added Mass & Damping.

The frequency dependent added mass and damping coefficients are shown.

Left click in the diagram shows the numerical value of the cursor position.Right click in the diagram gives the following options:

� Copy to Clipboard (puts figure in clipboard) � Show Cursor � Full Screen � Settings (change axis scale)


Motion Equation Coefficients.

The frequency dependent added mass and damping coefficients are shown.

of 56


See Also:

� View CHDB


Introduction Working with RAO's

RAO is an abreviation of 'Response Amplitude Operators'. The RAO delivers the response motion per unit wave height.

Calculating a RAO requires a hydrodynamic database. In the Hydrodynamic database draft, speed, heading, and frequency dependent parameters were stored. The RAO requires that restoring parameters, viscous damping, and a load distribution are known.

creating a Rao configuration/RAO Responses.

Octopus Office can calculate so-called 'primary' or 'basic' responses, 'user-defined' responses, 'combined' responses and sectional loads.To create a RAO configuration: Right mouse click in the tree (left pane) at CHDB

Type a name which is assigned to the RAO configuration

� Basic responses are always required. The basic responses are motions of the motion reference point (surge, sway, heave, roll, pitch, yaw) � Sectional Loads are the forces and moments acting on a point in a sectional plane of the hull. � Relative motions are the relative motions at different positions of the vessel. The vertical position of these points is in the waterline. � Angular responses are absolute velocities and accelerations in 'Acting Point' on the ship. Angular responses are derived from the primary motion

responses by taking single and double time-derivates.� Point responses are absolute motions in 'Acting Points' on the ship. Point responses are derived from the primary responses. Motions are calculated by

translation, velocities and accelerations are calculated from single and double time-derivates.� Combined responses are responses which are a linear combination of 'basic' and/or 'user-defined' responses. Using this feature you can define any kind

of response, which can be expressed as a linear combination of other responses. Please note that all the phase information is maintained.

The RAO's for the basic responses are calculated in relation to the COG of the system.

of 56


Configuration of the sectional loads is done by clicking button Sectional Loads. The following dialog appears:

Sectional loads can be calculated in the X-plane, Y-plane and Z-plane. The first coordinate defines the plane, the second and third coordinate specifies a point on the selected plane.

Configuration of the relative motions is done by clicking button Add Relative Motion. The following dialog appears:

� 'Name' : Type the name for this response � 'Acting point' : Definition of the x,y,z-coordinates of the point of interest.

To configure angular responses click the button Angular Responses. The following dialog appears:

To add angular responses to the configuration check the desired responses andto remove angular responses from the configuration uncheck the unwanted repsonses.

To configure linear responses click the button Add User Response. The following dialog appears:

To configure linear responses select an acting point as reference point for the calculations.Check the responses of interest or uncheck the unwanted responses.

To cCnfigure combined responses click then button Add Combined Response. The simplest application of this feature is a combined response with only one scaled response component. This way you can define responses in any unit. For example: a conversion from [deg] to [rad] is made by scaling the roll motion with a factor pi/180, = 0.01745 (see dialog below).

of 56


See Also:

� Definition Coordinate System� Definition Motions� Introduction RAO� Bilge Keel� Roll Damping� Stochastic Linearisation� Anti Roll Devices

See Also:

� Introduction RAO� RAO Responses� Roll Damping� Stochastic Linearisation� Anti Roll Devices

To calculate the response motion use derivation 'None', to calculate the response velocity use derivation 'Once' and to calculate the response acceleration use the 'Second' derivation.

Bilge Keel.

Add a bilge keel:

� Enter the distance from APP to aft end of bilge keel and enter the distance from APP to fore end of bilge keel. � Enter the bilge keel height in [m]. (Height is the distance from tip of bilge keel perpendicular to the hull.) � Check the positions of the bilge keel as displayed in the hull view.

Moving a bilge keel can be done by:

� Modify the distances in the edit boxes. � Or hold the CTRL-key and the SHIFT-key and press the left mouse button on the bilge keel aft end or fore end and then move the mouse while holding

these three buttons pressed, to the new location.

Select the "Use defaults" button to use the default settings

Note the following: The bilge keel only is taken in account when the roll damping method 'Ikeda' is selected in the Roll Damping tab. When using the Ikeda method the 'bilge keel roll damping coefficient (B44k)' must be selected too. See also Roll Damping.

Tuning by means of changing height bilge keel.

It may be difficult to achieve the required degree of correlation between measured and calculated roll motion, or the related transverse accelerations. If model tests or full scale results are available, a further tuning of roll motion or transverse acceleration can be applied.

This tuning can be done by modification of the viscous damping contribution. Tuning can be done of roll angles or transverse accelerations.

A practical way to increase the viscous damping is to increase the height of the bilge keel. This has an immediate effect on the magnitude of the total roll damping in a given sea state. The physical explanation for increasing the bilge keel height to a much larger artificial bilge keel is to account for effects which have not been modeled in a common seakeeping model. By varying the bilge keel height roll motion or transverse accelerations can be tuned. Of course this procedure can only be applied if reference material in the form of measurements is available.

Roll Damping.

The following roll damping options are available:

of 56


� No viscous roll damping � Frequency-dependent potential damping, viscous damping calculated at natural frequency� Ikeda method

Frequency-dependent potential damping

The non-dimensional total roll damping coefficients �1

and �2 at forward ship speed V have been determined at the natural frequency �

0: � = �

1 + �

2��

a by model tests. The

non-linear part of this damping, �2��

a, is assumed to be proportional to the frequency of oscillation. So, at each frequency of encounter, �

e, the total roll damping coefficient

is defined by:

The non-dimensional non-linear total roll-damping coefficient �, found from free rolling tests, as given in figure-d, is expressed by:

in which �a is the roll amplitude in radians, �

e is the frequency of oscillation (encounter frequency) and �

0 is the natural roll frequency in radians per second.

The coefficients �1

and �2 will provide an equivalent total coefficient . From this coefficient and the calculated potential damping coefficient , an

equivalent additional roll damping coefficient can be found:

The non-dimensional total roll damping coefficients �1

and �2 at forward ship speed V have been determined at the natural frequency �

0: � = �

1 + �

2��

a by model tests. The

non-linear part of this damping, �2��

a, is assumed to be proportional to the frequency of oscillation. At the natural frequency, the additional damping coefficient, N44a(�

0,�

a),

will be determined and the non-linear part will be added for the other frequencies of oscillation. So, at each frequency of encounter, �e, the roll damping coefficients are

defined by:

of 56


See Also:

� Introduction RAO� RAO Responses� Bilge Keel� Stochastic Linearisation� Anti Roll Devices� Introduction CHDB

Ikeda method

Ikeda`s method The additional roll damping coefficient, N44a(we,fa)Ikeda, is estimated by the empirical method of Ikeda and the potential damping, N44p(we), will be added:

This method can not be used for unusual ship forms, for very full ship forms and for ships with a large breadth to draught ratio. Even a few cross-sections with a large breadth to draught ratio can result in an extremely large eddy-making component of the roll damping. So, always judge the components of this damping. See Octopus Seaway Theory at www.amarcon.com/support and click documentation for more information.

The 'correction on the potential damping coefficient due to forward speed (B44s)' component should only be selected when a 2D CHDB is used. When a 3D CHDB is used, this component is already included in the CHDB.

Stochastic Linearisation.

Define the different sea states for which the linearization should be done. The spectrum used for the stochastic linearisation is a Jonswap spectrum. Remember, Jonswap with gamma = 1 is equal to the Pierson Moscowitz spectrum.

Since the viscous roll damping coefficient itself is a function of the roll amplitude and frequency, it results in a roll transfer function which is nonlinear in the wave height. This implies that the linearized roll transfer function varies per sea state.

To account for the nonlinear viscous damping behaviour, the sea state dependent roll RAO's are solved in an iterative manner by applying the principle of stochastic linearization, as shown below. The viscous damping is estimated using a start-value for the roll motion. The result is a roll RAO. This RAO is used to calculate the roll angle in a particular sea state. If the roll angle is equal to the assumed roll, convergence has been achieved. Else a new roll damping is computed using a larger or smaller roll angle, the roll RAO is re-calculated and a new roll response in the particular sea state is calculated. This loop is repeated until convergence has been obtained.

of 56


See Also:

� Introduction RAO� RAO Responses� Bilge Keel� Roll Damping� Anti Roll Devices

Anti Roll Devices

Anti roll devices deliver a counteracting moment to prevent the ship from rolling. These devices have to be tuned in such a way so they deliver the right moment at the right time. Anti-roll devices can be seperated into two different types: the active and passive anti roll device. Several examples of active anti roll devices are: stabilising fins, rudders, moveable mass, or a torque machine. Passive anti roll devices are free surface tanks or U-shaped anti roll tanks for instance. Sometimes, anti roll tanks have a different shape than the 'usual' squared ones. These free surface tanks should also be inserted as active anti roll (user defined) devices.

In case anti roll devices are present on the vessel, the devices can be managed through the buttons Add Device and Remove Device.In Office two types of roll devices can be modelled: 'Tank Devices', the passive anti roll devices, that can be modelled acording to the theory by 'Van den Bosch/Vugts' and 'Verhagen/Van Wijngaarden'. Tanks that cannot be modelled according to this theory have to be modelled as a user defined anti-roll tanks.The anti roll tanks also influence the mass, radii of gyration and free surface. In the loading condition file these parameters should be managed manually. The reason that the mass file is not updated automatically is to due to the many different types of anti-roll devices that can be used on ships, and to avoid confusion between different methods. For the mathematical implementation of anti roll tanks see Octopus Seaway Theory at www.amarcon.com/support click documentation for more information.

Configuration Anti Roll Devices:

� 'Device Name': name of the anti roll tank � 'Device Type': type of anti roll device ('Tank' or 'Other') � 'Device Method': type of anti roll device

('Van den Bosch/Vugts', 'Verhagen/Van Wijngaarden' or 'User Defined')

In case of tanks:

� 'Actual Level': Level in m of the still water level of the anti roll tank � 'Density': Density of the fluid in the anti roll tank � 'Position Aft': Position of the anti roll tank with respect to aft perpendicular � 'Height Bottom': Position of the bottom of anti roll tank with respect to keel � 'Length': Length of the anti roll tank in m � 'Width': Width of the anti roll tank in m, usually almost equal to the beam of the vessel

Anti roll tanks can also be defined by adding RAO's for different levels and roll angles. Octopus interpolates for intermediate frquencies and phase angles. These levels can be managed by using the buttons 'Add Level' and 'Remove Level'.

Anti Roll Tank using method Van den Bosch/Vugts Other anti roll device

of 56


See Also:

� Introduction RAO� RAO Responses� Bilge Keel� Roll Damping� Stochastic Linearisation

Inserting a RAO requires a a frequency, amplitude and a phase lag.

When selecting 'Device Type' as 'Other' active anti roll devices can be modelled by inserting a RAO. The mean roll angle is defined to give the possibility to add linear and non linear effects. The anti-roll device can deliver a greater counteracting moment if the ship has a greater mean roll angle.

Probably, the best way to imagine the way the anti roll moment curve works is by seeing it as a time dependent oscillatory moment. The oscillatory motion of the anti roll device is implemented mathematically in the motions in following way:M(t)= M

amplitude(omega)*cos(omega*t+phase)

In the software, this is calculated as a frequency based anti roll moment curve.

Loading Condition.

To add a loading condition:

� Right click at 'Loading Conditions' in the tree at CHDB. Since a loading condition is vessel specific, the loading conditions are located under a chdb.

� Type the name of the loading condition. � Then a dialog with two tabs will appear. One called Summary and one called Mass Details. Select the latter one � Right click at 'All Mass Items' to add a mass group � Select the created mass group by left click � Add a mass by clicking one of the buttons in the lower part of the dialog:

� Add GMP� Add 1D� Add 2D� Add 3D

� Or right click on 'All Mass Items' or mass group to Import Mass Groups from other Loading Condition files. � After the Mass Items have been created, Select tab Summary� Press button Calculate to calculate the mass distribution

The result after pressing Calculate is presented in a numerical and graphical way, see the picture below:

Add GMP

Fill in the required numbers for draft, KG or GM.When the box is closed by clicking OK the corresponding mass distribution is calculated.

Add 1D

Fill in the required mass items. Positions have to be entered in the coordinated system with 0 point at (APP,CL,BL)

Add 2D


of 56


See Also:

� Definition Coordinate System� Introduction RAO

See Also:

� Introduction RAO

Add 3D


Import Mass Groups

Click Browse to select a loading condition file.Check the required mass groups and click OK.

Import Loading Condition

To import a loading condition:

� Right click at 'Loading Conditions' in the tree at CHDB. Since a loading condition is vessel specific, the loading conditions are located under a chdb. � Choose Import from the menu.

� Type the name of the loading condition. � Browse to a 3rd party loading condition file. � Select the type of decoder. � Click OK

External Condition.

To add an external condition:

� Right click at 'Loading Conditions' in the tree at CHDB. Since a loading condition is vessel specific, the loading conditions are located under a chdb.

� Type the name of the external condition. � Right click at 'All External Conditions' to add a external condition.

External Conditions:External condition can be defined in matrixes(6x6) for mass, added mass, damping and restoring coeffients. Added mass, damping and restoring coeffients matrixes can be defined for each combination of speed and encounter frequency. If an external condition is not defined relative to the coordinated system with 0 point at (APP,CL,BL) than is not not nessecary to recalculate all matrixes. The translation to (APP,CL,BL) can be given at the Definition of the coordinate system.

To define matrixes for combinations of speed and encounter frequency define speeds and encounter frequencies first by clicking the Define... button. Note that the checkbox Indepenent from speed and frequency must be unchecked.

Linear Springs:A spring condition can be defined as one restoring matrix.

The linear spring coefficients in the three directions in a certain point (xp, py, pz) are defined by (Cpx, Cpy, Cpz). The units of these coefficients are kN/m. This results in the following restoring matrix:

� Surge

� Sway

of 56


See Also:

� Definition Coordinate System� Introduction RAO

� Heave

� Roll

� Pitch

� Yaw

External Condition File Description.

EXTCON - External condition

NFIELD No. of data fields in this record (incl. this field)

ICON Internal condition reference no.

ICONTY Condition type

NLABEL Label length

LABEL Condition label (character string with length=NLABEL)

REFX X acting point APP

REFY Y acting point CL

REFZ Z acting point BL

NUMSPD No. of speeds

ISPDTY Speed unit

NUMRAD No. of encounter frequencies

IRADTY Frequency unit

Repeat for I=1,NUMSPD

SPEED Speed

Next I

Repeat for I=1,NUMRAD

RAD Frequency

Next I

Comment:

ICONTY Condition type

0 other

1 spring

ISPDTY Speed unit

1 m/s

2 kn

IRADTY Frequency unit

1 s

2 1/s

3 rad/s

EXTMAT - External 6 - 6 matrix

NFIELD No. of data fields in this record (incl. this field)

ICON Internal condition reference no.

IMATRIX Internal matrix reference no.

ISPD Speed index

IRAD Frequency index

IMATTY Matrix type

IGLOBAL Dependency type

Repeat for I=1,6

Repeat for J=1,6

MAT(I,J) Hydrodynamic matrix

Next I

Next J

Comment:

IMATTY Matrix type

11 Mass matrix

12 Added mass matrix

21 Damping matrix

of 56


See Also:

� Introduction RAO� View RAO� Reports� Definition Motions

31 Restoring matrix

IGLOBAL Dependency type

0 speed and freqency dependent

1 speed and frequency independent

Calculate RAO.

After the RAO configuration is prepared, by defining bilge keel, anti roll tanks and so on, do the following steps to create a RAO calculation:

� Right mouse click in the tree (left pane) at RAO Config:

� Type a name which is assigned to the calculation � Select the loading condition for which the RAO should be calculated, browse to the loading condition by clicking button Browse: � Optionaly select a external condition for which the RAO should be calculated, browse to the external condition by clicking button Browse: � Click button Calculate. When these calculations are finished the results can be observed in the three tabs below.

View RAO.

The properties which are valid for the RAO are visible in tab 'General':

� Motion reference point � Selected Responses � Speed & Heading � Wave frequencies � Sea States

The calculated RAO is presented in a graphical way, select tab "RAO's", the following window appears:

By left click and drag in the colormap the heading for the diagrams at the right can be changed.Right click in the colormap or diagrams gives the following options:


By clicking button the numerical values are displayed in a table. Right click in the table copies the numerical values to the clipboard. Clicking button

displays the diagrams again.

of 56


See Also:

� Introduction RAO� Calculate RAO� Reports� Definition Motions

See Also:

� Introduction RAO� Calculate RAO� View RAO� Definition Motions

View Reports.

This tab gives the possibility to view RAO for different selected speeds and headings.

The calculated RAO is presented in a graphical way, by selecting the checkboxes on the left pf the dialog it is possible to manage the data that will be displayed. Right click in the colormap or diagrams gives the following options:



Export to Seaway results.

OCTOPUS Office is able to make an export the RAO calculation in a SEAWAY-output format.To export a RAO: Right mouse click in the tree (left pane) at RAO

Select the required load case and the sea state (used for stochastic linearisation).Browse for an export file and click 'Convert'.

of 56


See Also:

� Export to Onboard� Introduction RAO

The results are converted to the *.out file.

Export to OCTOPUS Onboard.

OCTOPUS Office is also able to make an export file in *.xml-format for OCTOPUS Onboard.To export a RAO: Right mouse click in the tree (left pane) at RAO, choose Export to Onboard....

A dialog appears with the different RAO-configurations that in which modifications can be made if that is derired. The different tabs are: � Responses � Bilge Keels � Roll Damping � Free Surface Tanks � Anti Roll Moment Curves � Stochastic Linearisation The options and parameters in these tabs are copied from the RAO-configurations made earlier when adding a RAO-configuration. If it is necessary to change these configurations for Onboard, it is possible to do that here.

Then a next dialog will appear asking what information of the RAO configurations will be exported to Onboard-format. After defining a Project ID and inserting a file name and location too, press the Export command button:

The results are then converted to the *.xml file.

of 56


See Also:� Export to SEAWAY� Introduction RAO� RAO Responses� Bilge Keel� Roll Damping� Stochastic Linearisation� Anti Roll Moment Curves

Introduction to SEAWAY.

SEAWAY is a strip theory based program to calculate the hydromechanical parameters, wave forces, Respone Amplitude Operators, Statistics, and added resistance due to waves. These had to be investigated earlier by doing tank tests. Strip theory was initially introduces by Ursell who calculated the added mass, damping, and hydrodynamic forces of a long cylinder. Later on, other scientists made modifications. Lewis introduced conformal mapping which allowed for more reliable modelling of ships. By combining a set of different frames or 'strips' and integrating the added mass, damping and hydrodynamical forces over the length of the ship it was possible to calculate the total wave forces and moments. Because it was possible to calculate all the parameters for a total formulations of the equations of motions it was possible to predict the ships behabviour in waves aforehand. Later Tasai, Frank and Keil made other modifications/supplementations. SEAWAY was made by Journee. The program combined the striptheory of ursell, the modifications like conformal mapping, statistics into one single program, which speeded up design process and enabled voyage planning.

Octopus Office is based on the benefits SEAWAY offers.

Throughout the whole program the following bar will be possible

This bar leaves the options to import a former SEAWAY project. The default options make it possible to switch back to default values in all tabs. Calculate is an option used after going through all the tabs, for it concerns the total calculations, not intermediate ones.

Loading Condition

Start a SEAWAY project by a right click in the project tree and select Add SEAWAY Calculation...

Insert a project name in the dialog that appears. After that the following window will appear in which the print options can be managed. The selection of option depends on what the desired output of the *.out file is. This can differ per project.

It is possible to print the following in one single output file:

� Input � Geometry � Hydromechanical coefficients � Transfer functions � Spectral Data

The results are visible in a numerical and graphical way, see tabs: General, Sea Condition, Short Term

Start a SEAWAY calculation.

of 56


See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Numerical Method� Speeds� Headings� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Springs� Selected Points

The tab loading condition is as follows:

This tab is aimed at defining ship parameters, loading condition and construction of the mass matrices and restoring matrices.Browse to a *.hul file that is suitable for the desired calculations.

It is possible to define the loading condition according to the standard parameters in the lower part of the tab, but it is also possible to import/construct a mass distribution.

When the mass distribution was imported a summary will be shown in the lower part of the tab Loading Condition.The default loading conditions are constructed in the following way:

� Displacement: is calculated according to midship draft and trim. SEAWAY interpolates with frames and offsets from the hull file. � LCB=LCG and YCG: The longitudinal and transverse center of bouyancy are calculated according with help of the hull file. � KG: is calculated according to a standard GM-value of 1.0 meters. SEAWAY calculated the KB, and BM values. The distance between the center of

gravity is then finally calculated as follows: KG=KB+BM-GM. It is possible to manage either the KG-value or the GM-value by enabling or disabling the text boxes by clicking on the option buttons.

� Rxx, Ryy, and Rzz: Calculated according to standard values Rxx=0.35*B, Ryy=0.28*L, Rzz=0.28*L. These values Depend strongly on the type of ship involved in the calculations. It is stringly recommended to check these radii of gyrations for correctness.

� GG': is the value of correction for free surface. This value is influenced by free surface tanks, fuel tanks of green water for instance.

of 56


� Regular Waves� Irregular Seastates� Seakeepin Criteria� Physical Constants

See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Headings� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Springs� Selected Points� Regular Waves� Irregular Seastates� Seakeepin Criteria� Physical Constants

Speeds

The tab shows the options for selecting the number and values of speeds. The speeds can be calculated automatically acoording to the maximum value inserted on the right of the dialog, but they can also be managed manually by selecting a cell in the table and changing the value.

Numerical Method

The tab shows the options regarding the cjhoice of numerical method. This has consequences for the calculation time and the accuracy of the results. It is recommended to take a look at SEAWAY Strip Theory on the websit www.amarcon.com/support and click documentation. The Tab numercal methods is as follows:

A short summary of the options will be given below.

of 56


See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Speeds� Headings� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Springs� Selected Points� Regular Waves� Irregular Seastates� Seakeepin Criteria� Physical Constants

See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Springs� Selected Points� Regular Waves� Irregular Seastates� Seakeepin Criteria� Physical Constants

� Ordinary Strip Theory or Modified Strip Theory: The ordinary strip theory method and the modified strip theory make distiction in forward speed. The ordinary strip method has an intuitive correction for forward speed. The modified strip theory has a beter formulation. It is recommended to keep all calculations under Froude number 0.3

� Classical Wave Loads or Diffraction Wave Loads: The classical wave loads longitudinal and tranverse center of bouyancy are also calculated according with help of the hull file.

� Potential Solution Method: � Tasai introduced Lewis conformal mapping into the strip theory method as was set up by Ursell. This method described the frame or strip of the

ship with help of two parameters. Later Tasai introduced a 10 parameter mapping method. � Frank introduced a method to describe submerged hull sections and hull sections that could not be properly modelled by the conformal mapping

method - not even Tasai's 10 close fit method. This concerns bulbouw bows or hull shapes that can be found mostly in aft hull sections. � Tasai and Frank are both only applicable for deep water cases. Keil introduced a mthod to calculate the hydrodynamical coefficients for shallow

water acoording to Lewis's mapping method. � Free moedes of motion: It is possible to manage the number and kind of degrees of freedom in the calculations. � In the lower part of the tab a plot of the frames is shown acoompanied by an indication of the potential solution method that will calculate the

hydrodynamical parameters.

Headings

The tab shows the options for the selection of desired headings. A value of 7 headings produces calculations for every 30 degrees of heading, a value of 13 calculates for every 15 degrees and a value of 19 calculates the hydrodynamical coefficients for every 10 degrees.selecting the number and values of speeds. The headings can be calculated automatically acoording to the maximum value inserted on the right of the dialog, but they can also be managed manually by selecting a cell in the table and changing the value.

Viscous Damping

of 56


See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Headings� Sectional Loads� Anti Roll Moment Curve� Free Surface Tanks� Springs� Selected Points� Regular Waves� Irregular Seastates� Seakeepin Criteria� Physical Constants

See Also:

� Introduction to SEAWAY and Strip Theory

Viscous damping only plays a significant role when it comes to roll motions. The tam shows tyhe different options that need to be managed for the correct calculation of the roll motions of the ship. This can include forward speed corrections, geometric description of the keel and the method.

For most cases it is recommended to use Ikeda's method for roll damping. This has given satisfactory results in the past. Ikeda devides Roll damping into several parts. One where he tested roll damping which is influenced by bilge keels. He did experiments where elipsoids did and dit not have bilge keels. Another part includesdamping as a consequence of pressure regions that are created while rolling, these pressure disturbance coeficcients depend on the hull shape. For further information it is recommended to see the Octopus Seaway Theory on the website www.amarcon.com/support and option DocumentationIn the lower part of the dialog it is possible to define the geometric parameters of the bilge keel

Sectional Loads

This tab allows for extra output of loads on different sections. This can be necessary for strength assessments.

of 56


� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Headings� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Springs� Selected Points� Regular Waves� Irregular Seastates� Seakeepin Criteria� Physical Constants

See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Headings� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Springs� Selected Points� Regular Waves� Irregular Seastates� Seakeepin Criteria� Physical Constants

Free Surface Tanks

Verhagen en van Wijngaarden provided some theory regarding Anti roll tanks in 1965. Later Van den Bosch and Vughts provided extensive quantative results to this theory.

The approach by Van den Bosch and Vughts can be recommended when using free surface methods.The definition of the orientation of axis and the dimensions concerning the theory on free surface tanks can be observed in the followng figure:

Anti Roll Moment Curves

Anti roll moment curves are used to define the anti roll devices. These can be rudders, stabilising fins or movable masses that can be programmed to reduce the ship's roll motion.

of 56


See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Headings� Sectional Loads� Viscous Damping� Free Surface Tanks� Springs� Selected Points� Regular Waves� Irregular Seastates� Seakeepin Criteria� Physical Constants

The anti roll moment curve can be programmed like a RAO. Characteristic values for each frequency can be inserted to provide certain contratrotating moments with a certain phase lag.

Note that in this case a mean roll angle is required input. This refers to cases where the anti roll moment curve is not defined as a free surface tank, but as a free surface wall tank. These are not the free surface tanks like were analysed by Verhage, Van Wijngaarde, Van den Bosch and Vughts, see Free Surface Tanks. Free surface wall tanks are tanks with extra bulkheads with holes for instance. Or maybe a tank with a varaition in depth. Anyway, these free surface wall tanks often have nonlinear effect which can be taken into account by inserting a RAO for eacht different mean roll angle. When the effect is linear, it is only necessary to insert the same RAO for two different mean roll angles. Seaway will interpolate in values inbetween.

Note that the free surface effect GG' does not have to be changed in the earlier tab Loading Condition. The effect of extra free surface moment is taken into consideration automatically by SEAWAY.

For further information it is recommended to see the Octopus Seaway Theory on the website www.amarcon.com/support and option Documentation

Springs

This tab allows for external springs to be added to the restoring matrix. These can be mooring lines of offshore structures for example.

of 56


See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Headings� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Selected Points� Regular Waves� Irregular Seastates� Seakeepin Criteria� Physical Constants

See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Headings� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Springs� Selected Points� Irregular Seastates� Seakeepin Criteria� Physical Constants

Insert values in the table after enabling the input by clicking on include springs. Insert the position and the spring coefficients for very spring.

Regular Waves

This tab is used to manage the range of wave frequencies for which the frequency dependent coefficients and the RAO's have to be calculated. The range of frequencies give is calculated automatically according to main parameters of the ship, but can be managed by the user by selecting the right values and options manually.

Selected Points

In Selected Points it is possible to calculate some extra motion points on the ship, for instance accelerations on a certain point of the cargo or the absolute motions and accelerations in the wheelhouse.

of 56


See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Headings� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Springs� Regular Waves� Irregular Seastates� Seakeepin Criteria� Physical Constants

It is also possible to include dynamic swell-up in the calculations. Dynamic swell includes the effect of the bow/ship shape in the absolute and relative motions. including dynamic swell up increases the relative motions and increases the chance of taking shipping green water. Dynamic swell up is purely a consequence of shipmotions. It should not be confused with static swell up, which is swell up due to forward speed of the ship. The method in SEAWAY is only valid when:

� 0.60 < CB

< 0.80

� 0.16 < Fn < 0.29

See also the "OCTOPUS Strip Theory" on the wesite www.amarcon.com/support and click documentation

Irregular Sea States

This tab only enables short term statistics by selecting a sea spectrum or by inserting a sea state manually. Jonswap is used for sea spectra encountered in the North Sea. This spectrum is sharper peak than Neumann and Bretschneider. The sharpness of this peak is determined by the value gamma, which is the same as the Bretschneider spectrum when the value for this gamma factor is 1.0. See also the more extensive documentation in wavespectra.

of 56


See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Headings� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Springs� Selected Points� Regular Waves� Seakeepin Criteria� Physical Constants

See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Headings� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Springs� Selected Points� Regular Waves� Irregular Seastates� Seakeepin Criteria

Physical Constants

This tab allows the user to define the units in which the output is generated. Changing the density and waterdepth might be relevant in some cases.

Seakeeping Criteria

Seakeeping criteria refer to slamming and motion sickness. The default values are determined by the slamming crietria as defined by Ochi. These criteria are emergeence of the bow at 10% of the ships length from the bow, and a minimum vertical relative velocity.

of 56


See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Headings� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Springs� Selected Points� Regular Waves� Irregular Seastates� Physical Constants

It is also possible to define other criteria for position and slamming coefficient. Connoly also did research regarding slamming criteria. He developed a relation between slampressure and distance from App of the ship. Slampressure is a result of a certain deadrise angle and a impact velocity. Connoly's criteria are generally better for developing the seakeeping criteria. See the Octopus Seaway Theory on the website www.amarcon.com/support and option Documentation. In the lower part of the dialog it is possible to define the MSI reference period. MSI stands for Motion Sickness Index as defined by O'Hanlan and McCauly.

Running Seaway in Batch Mode

Running seaway in Batch mode can be interesting when multiple seaway calculations have to be done. Create Seaway Batch calculation by a right click in the project tree and define a name for the calculations.

The following dialog is made to specify which calculations must be done. The user should select a number of cases befor pressing Run

of 56


See Also:

� Introduction to SEAWAY and Strip Theory� Start a SEAWAY Calculation� Loading Condition� Numerical Method� Speeds� Headings� Sectional Loads� Viscous Damping� Anti Roll Moment Curve� Free Surface Tanks� Springs� Selected Points� Regular Waves� Seakeepin Criteria� Physical Constants

To add a SEAWAY calculation click the button Add and make a selection from the different options that are offered. The list should represent the list of names of seaway calculations in the project tree.

Introduction to Statistics

Statistics enable a sea state to be properly modelled in a summation of a selection of random waves (frequency, height, etc). Via known RAO one can calculate the statistics of the reponse of the vessel, motion point, etc...

Before statistical calculations can be performed, sea state should be modelled under Common in the project tree. Sea states can be modelled in a spectrum,

scatter diagram, or can be imported form a 3rd party.

Configure Statistics Responses.

of 56


See Also:

� Sea State Statistics� Wave Scatter Diagram Statistics� W3C Wave Database Statistics� Definition Statistical Operators

See Also:

Before statistical calculations can be done, assign the responses and reference period.To create Seatste Calculations, right mouse click in the tree (left pane) at RAO:

Then type a name which is assigned to the statistical calculation

Then a dialog appears in whci the following must be done:

� Define the reference period in the field 'Reference Period'. This reference period refers to the time a seastate is regarded to be constant. A seastatedoes not change very much in a period of 3 hours, this is a good value for the reference period.

� Define the number of heading directions to betaken (at one side). a value of 19 divides results in a 10 degree mesh. � Manage the responses for which the statistics should be calculated, by selecting the response and clicking buttons

� Use the Up and Down buttons to order the responses in the desired order of appearance in the further statistics calculations.

Once the configuration of the stastics is ready, the following statistical calculations can be performed:

� Sea State Statistics � W3C Wave Database Statistics � Wave Scatter Diagram Statistics

Calculate Sea State Statistics.

To create sea state statistics:Right mouse click in the tree (left pane) at Statistics Configuration:

Type a name which is assigned to the sea state statistics calculation, after doing this the following window appears:

Select the sea states for which the statistics should be calculated, browse to the environment file by clicking button Browse Click button Calculate. By navigating through the tabs 'Spectral Moments', 'Statistics', and 'Envelopes' it is possible to observe the results. In tab 'Spectral Moments' the spectral moments of the different sea states, speeds and headings are visible. The results are also available visible in a graphical way, see: tabs Statistics and Envelopes

By a right mouse click on the table, graphs and polar diagrams it is possible to copy the information to the clipboard.

of 56


� Configure Statistics Responses� Short Term Sea State Statistics� Sea state Envelopes� Sea States� Definition Statistical Operators

Short Term Sea State Statistics.

Short term statistics can be shown for different responses, sea states and operator. They can also be given as a envelope by selecting the checkbox left of the The following opertaors are available.

� Most Probable Maximum � MSI, Motion Sickness Index � Slamming % � Slamming (n/hr) � P Outcrossing � N Outcrossing � Significant (Single) � Significant (Double) � Rayleigh

Short term statistics is calculated for the reference period give earlier when setting up the configurations and reponses. The values displayed in the plots will be different if another reference time is selected. MSI refers to the Motion Sickness Studies done by O'Hanlan and McCauly taken into ISO2631. Slamming criteria are defined according to the theory by Ochi. Note that when using the slamming operators, Slamming should also be inserted as a response in the response configurations including the relative motion at 0.90L. Level is used as a maximum value (criterion) for the diagram. By default level has the value of criterion as configured in Statistics Configuration. To view the envelope of all responses check All, all responses that have a level value will contribute to the envelope.

By left click and drag in the colormap the heading and speed for the diagrams at the right can be changed.Right click in the colormap or diagrams gives the following options:


By clicking button on the right of the dialog the numerical values are displayed in a table. Right click in the table copies the numerical values to the

clipboard. Clicking button displays the diagrams again.

By clicking button on the left of the dialog a polar plot is shown:

of 56


See Also:

� Create Sea State Statistics� Sea State Envelopes� Configure Statistics Responses� Create Sea States� Definition Statistical Operators

Note that it is possible to display the resonance areas -high wave groups, surfing/broaching, parametric roll and synchronic roll- in operational conditions of the ship.

The resonance diagrams are constructed according to the German SBGGuidelines. For parametric roll these guidelines state the following:

� The waves should be higher than the threshold value (approximately 5 meter for a Panamax container ship). � The pitch period should be close to the encounter period of the wave. � The roll period should be close to double the encounter period of the wave. � The wave direction should be close to head waves or following waves.

By right click on the mouse the following options are also possible in order to manage the modify the plot options. When selecting the option Settings it is not

only possible to manage the axis setting, but also to manage the visibility of the resonance areas.

of 56


See Also:

� Create Sea State Statistics� Short Term Sea States Statistics� Configure Statistics Responses� Create Sea States� Definition Heading� Definition Statistical Operators

Envelopes sea state statistics.

Envelopes can be shown for different responses and operator.The tab Sea States gives the envelope for all sea states where the values are calculated for the selected speeds and headings, the tab Speed gives the envelope for all speeds and sea states using the selected headings and the tab Headings gives the envelope for all headings and sea states for all selected speeds.

Right click in the diagrams gives the following options:


In the fields 'Select Speeds' and 'Select Headings' a particualar speed or heading is shown in the envelope. For instance, when directionality and heading control is possible, a range of headings can be excluded. This is only the case for self-propelled vessels with redundant propulsion systems.

Wave Scatter Diagram Statistics.

To create wave scatter diagram statistics:Right mouse click in the tree (left pane) at Statistics Configuration:

Type a name which is assigned to the scatter diagram statistics calculation, after doing this the following window appears:

of 56


See Also:

� Scatter Diagram Short Term Statistics� Scatter Diagram Long Term Statistics� Configure Statistics Responses� Wave Scatter Diagram� Definition Statistical Operators

Browse to the scatter diagram for which the statistics should be calculated by clicking button Browse. Then click button Calculate. By navigating through the tabs 'Short Term', 'Long Term' it is possible to observe the results, see: tabs Short Term and Long Term. By a right mouse click on the table, graphs and polar diagrams it is possible to copy the information to the clipboard.

Short Term Wave Scatter Diagram Statistics.

Short term statistics can be shown for different responses, sea states and operator. Different operators are available:

� Most Probable Maximum � MSI, Motion Sickness Index � Slamming % � Slamming (n/hr) � P Outcrossing � N Outcrossing � Significant (Single) � Significant (Double) � Rayleigh

Short term statistics is calculated for the reference period given earlier when setting up the configurations and reponses. The values displayed in the plots will be different if another reference time is selected. MSI refers to the Motion Sickness Studies done by O'Hanlan and McCauly taken into ISO2631. Slamming criteria are defined according to the theory by Ochi. Note that when using the slamming operators, Slamming should also be inserted as a response in the response configurations including the relative motion at 0.90L. Level is used as a maximum value (criterion) for the diagram. By default level has the value of criterion as configured in Statistics Configuration.To view the envelope of all responses check All at the left of the response combo box, all responses that have a level value will contribute to the envelope. To view the envelope for all speeds check All at the left of the speed combo box and to view the envelope for all headings check All at the left of the heading combo box. Any combination of envelope is possible.

The left column displays the waveheight, the top row diplays the waveperiod and the right colomn gives the workability per sea height. The combined probability of all the sea states, where the response values do not exceeds the given level, results in the workability. In the above example the workability for

of 56


See Also:

� Scatter Diagram Long Term Statistics� Create Wave Scatter Diagram Statistics� Configure Statistics Responses� Wave Scatter Diagram� Definition Statistical Operators

seas up to 8 meters is 86%. Right click in the colormap or diagrams gives the possibility to copy information to the clipboard To obtain a polar diagram of a specific sea state double click in the scatter diagram of the sea state. Note that it is possible to display the resonance areas -high wave groups, surfing/broaching, parametric roll and synchronic roll- in operational conditions of the ship.

The resonance diagrams are constructed according to the German SBGGuidelines. For parametric roll these guidelines state the following:

� The waves should be higher than the threshold value (approximately 5 meter for a Panamax container ship). � The pitch period should be close to the encounter period of the wave. � The roll period should be close to double the encounter period of the wave. � The wave direction should be close to head waves or following waves.

By right click on the mouse the following options are also possible in order to manage the modify the plot options. When selecting the option Settings it is not

only possible to manage the axis setting, but also to manage the visibility of the resonance areas.

Long Term Wave Scatter Diagram Statistics.

Short term statistics are aimed at calculating the respoinse in a certain seastate. Long term statistics are aimed at calculating the statistics in the order of a ships lifetime.

Right click in the diagram gives the following options:

� Copy to Clipboard (puts figure in clipboard) � Show Cursor

of 56


See Also:

� Scatter Diagram Short Term Statistics� Create Wave Scatter Diagram Statistics� Configure Statistics Responses� Wave Scatter Diagram� Definition Statistical Operators

� Full Screen � Settings (change axis scale)

Different return periods are defined. It's possible to define a user defined return period, by entering a number. Enter the number in Years.By clicking button Config the following dialog appears:

It is also possible to assign a probability for each heading. For instance, when directionality and heading control are possible, a range of headings can be weighted less. This is only the case for self-propelled vessels with redundant propulsion systems.

Statistical W3C Analysis.

More elaborate analyses can be carried out when time series of waves are available. Using spectral data instead of derived wave parameters such as significant wave height, mean direction or zero-upcrossing period, ensures more accurate results, especially in multi-directional seas. Moreover, persistency effects are automatically included.

In Octopus Office, voyage simulations can be carried out by using the Argoss W3C-database. This historical world-wide wave database is the product of satellite observations and a 3rd generation wave model. It covers a period of 15 years with a time resolution of 3 hours. The wave condition at a particular date, time and location is described by a distribution of the energy, the direction and the directionality, as a function of the frequency. The position list of the voyage is used as input for voyage simulations. These simulations are carried out for different dates and time of departure, and repeated until convergence is obtained after 'N' simulations. The design values can be derived by defining a required success rate after simulating N voyages.

The W3C database is not part of Octopus Office 6, but is sold separately.

To create W3C statistics:

� Right mouse click in the tree (left pane) at Statistics Configuration:

� Type a name which is assigned to the W3C statistics calculation, after doing this the following window appears:

� Configure the analysis by clicking button Configure, after doing this the following window appears:

of 56


See Also:

� Configure Statistics Responses� Voyages

See Also:

� Statistical W3C Analysis� Configure Statistics Responses� Voyages

� Select the path where the Agross Databas is located by clicking button Browse. � Select the voyage by clicking button Browse. � Select the interval of the start date of the voyages by entering numbers in the fields 'Start Every'. � Select the number of starts by entering a number in the fields 'No. of Starts'. The startdates for each start will be incremented with the interval as

specified. � Select the time between the waypoints by entering a number in the field 'Time between waypoints [h]'. The minimum value is 3 hours, since the

resolution of the wave data in the Agross database is 3 hours. � Select years for which the voyage should be calculated. The total number of starts for which statistics is calculated is in this case : 1 x 13 = 13

starts. � Close the dialog by clicking button OK.

� Click button Calculate and the statistics is calculated.

The results are visible in a numerical and graphical way, see tabs: General, Sea Condition, Short Term and Long Term

General W3C Statistics.

The level (single amplitude), probability, return period and mean Tz is shown for every response. The results are visible in a numerical and graphical way, see tabs: Sea Condition, Short Term and Long Term

Sea condition W3C statistiscs.

of 56


See Also:

� Statistical W3C Analysis� Configure Statistics Responses� Voyages� Definition Statistical Operators

For each simulated voyage the sea condition during time is shown.Select a voyage in the field 'Voyage'. Voyages are ordered with respect to startdate.Select a response in the field 'Response'.



By clicking button it is possible to see the numerical values of which the graph is constructed of. Right click in the table enables to copy the numerical

values to the clipboard. Clicking button displays the diagrams again.

The results are visible in a numerical and graphical way, see tabs: General, Short Term and Long Term

Short term W3C statistiscs.

For each simulated voyage the short term statistics during time is shown.Select a voyage in the field 'Voyage'. Voyages are ordered with respect to startdate.Select a response in the field 'Response'. Different operators are available:

� Most Probable Maximum � P Outcrossing � N Outcrossing � Significant (Single) � Significant (Double) � Rayleigh

of 56


See Also:

� Statistical W3C Analysis� Configure Statistics Responses� Voyages� Definition Statistical Operators

See Also:

� Statistical W3C Analysis� Configure Statistics Responses� Voyages



By clicking button the numerical values shown in the graph can be displayed in a table. Right click gives the option to copy the values to the clipboard.

Clicking button displays the diagrams again.

The results are visible in a numerical and graphical way, see tabs: General, Sea Condition and Long Term

Long term W3C statistiscs.



Different return periods are predefined. It's possible to define a user defined return period, by entering a number in the last text box.

The results are visible in a numerical and graphical way, see tabs: General, Sea Condition, Short Term

Quick Guide

Introduction to the Quick Guide

The Quick Guide describes the steps needed to get started with Octopus Office.

To get a real quick start an example project is included in Octopus Office. Click File, Open... and select the 'Example Project' and browse through the project.

See Introduction Octopus Office for an introduction regarding the basic idea of Octopus Office.

The user Interface

When the tree-items in the left pane are Right Clicked on, the different options, available to that specific section, are displayed.To save any settings or results, use the "save" option from the file menu, or close the dialog and confirm the changes. The active dialog is marked in bold in the tree in the left pane. Tree-items can be marked in red. The reason is, that settings on a higher level on the branch have been changed. The changes are not automatically updated in the lower levels. The items, marked in red, have to be recalculated or updated manually, to display the correct results, according to the changed settings. After recalculation or updating the red marked items, Save the settings to unmark the items. See also Using the Workspace in the User Guide

Create a new project

To get a quick start, an example of a project which uses the Container_Ship_014 has been included in Octopus Office. To create this project by yourself, take the following steps:

� Start OCTOPUS Office

of 56


� Create a new project To create a new project, click File, New...

See also Create New Project in the User Guide

� Create Compiled HDB (Hydrodynamic DataBase) To create a CHDB an Hull and Grid file should be available.These files can be viewed or created with 2D Hull Modeller and 3D Hull Modeller.

� Click Tools, 2D Hull Modeller..., File, Open to view the Container_Ship_014 hull file. When necessary, edit the hull.

Close the 2D Hull Modeller. � Click Tools, 3D Hull Modeller... to create the Container_Ship_014.glv file, which is needed to create a 2D CHDB.

� Open the hull file, click File, Open and select the Container_Ship_014.hul file. � Create a mesh, click Geometry, Mesh. The following dialog appears:

� 'Draft Aft': Fill in draft Aft (15m) � 'Draft fwd': Fill in draft Aft (15m) � Click button OK to create the mesh.

� Check if the (0,0,0) position is equal to (APP,CL,BL). If so, Save the mesh as a Container_Ship_014.glv file: Click File, Save as.. and save the glv file.

� Close the 3D Hull Modeller. � To create a 2D- CHDB, click Tools, Create 2D CHDB...

of 56


� 'Hull file' specifies the location of the hull file. To select a location, click button Browse. The Hull Browser is opened. Select Container_Ship_014. Finally click button Open in the Hull Browser.

� 'Grid file' specifies the location of the grid (Container_Ship_014.glv) file. � 'Name' Type the name of the vessel and eventually a description. � 'CHDB file' type the name and the location of the CHDB file which will be created after clicking button Create.

See also 2D Hull Modeller in the User GuideSee also 3D Hull Modeller in the User GuideSee also Create 2D CHDB in the User GuideSee also View CHDB in the User Guide

� Add Compiled HDB At the top of the project tree, "Right click" the newly created project name and select "Add Compiled HDB" Enter a name and select "OK" At "Select CHDB file" , use the "Browse" button to locate to the CHDB file. By selecting the various tabs at the top of this screen, different types of information stored in the CHDB, can be displayed.

See also View CHDB in the User Guide

� Define Environment Expand the "Common" item from the tree to define Sea States, Wave Scatter Diagrams and Voyages.

� Sea State Section Right Click "Sea States" and select "Create Sea States" Enter a name and select OK Generate the sea states by entering numbers manually, or generate a range of sea states by clicking the "Define Sea States" button.

A sea state consists out of 1 or 2 wave systems, where the second wave system is defined with an angle with respect to the first wave system.

of 56


Typical use of 2 wave systems is when a combination of sea and swell should by applied.Sea States created or added in this section are used as Environment file in the Statistics Configuration.See also Sea States in the User Guide

� Voyages Section Right click "Voyages" and select "Create Voyage" Enter a name and select OK. A voyage is created by clicking on a specific location while holding the <ctrl> key pressed. Once a waypoint is generated its position can be changed by changing the values in the fields 'Latitude' and 'Longitude' manually. Assign a specific port to a waypoint by clicking button Port List.

From the file menu, select "save" or close the Voyage Section dialog. The created voyage file can now be used in the Wave Scatter Statistics or in the W3C statistics. See also Voyages in the User Guide

� Wave Scatter SectionRight click "Wave Scatter Diagram" and select the "Create Wave scatter Diagram" option. Enter a name and select OK.At the bottom of this screen, change the settings which defines the spectra, when necessary.

Click the "Scatter DB" button. At the bottom, select the applicable map and Scatter Database. Select the applicable area in the map, keep the <ctrl> pressed to select multiple areas.A voyage can also be imported. See the "Voyages" section on how to create a voyage.

When a voyage is selected, the weights for the different areas are created automatically. When necessary, these weights can be adjusted.

of 56


See also Wave Scatter Diagram in the User Guide

� Loading ConditionIn the left pane, right click Loading Condition. See Loading Condition how to create a loading condition.

See also Loading Condition in the User Guide

� Configure RAO calculation

First, a RAO configuration has to be created. In the left pane, right click the chdb in the tree and select the Create RAO Configuration option. Enter a name and select OK.

Edit the different settings like bilge keel, anti roll tanks for the RAO calculation, when necessary. Also define the motion reference point.See also RAO Responses in the User Guide

� Calculate RAOIn the tree in the left pane, right click the RAO Config and select the Create RAO Calculation option. Enter a name, and select OK. Browse to a Loading Condition and select "Calculate".

After finishing the calculations, the tabs display information stored in the RAO.See also Calculate RAO or View RAO in the User Guide

� Create a Statistics ConfigurationRight click on the RAO in the tree to create a Statistics Configuration.

of 56


Select the required responses. Use the left and right arrows to remove and add responses from the selection list. (User defined responses or combined responses can be created or edited at the Create RAO Configuration section). Click the "Update All Responses" button if User defined or combined responses are not displayed in the "All Responses" list. See also Config Statistics Responses in the User Guide

� StatisticsRight click the Statistics Configuration to create Scatter Calculations, Sea States calculation or W3C calculations.

� Sea State Calculation: Right Click the "statistics config" in the left pane and select Create Sea State Calculation. Enter a name and select OK. Browse to a Wave Sea State file. (See the Sea State Section on how to create or add a Sea State file). Select "calculate" to display the results. The calculation can take several seconds.See also Sea State Statistics in the User Guide

� Scatter Calculation: Right Click the "statistics config" in the left pane and select Create Scatter Calculation. Enter a name and select OK. Browse to a Wave scatter diagram file. (See the Wave Scatter Section on how to create or add a Wave scatter diagram file). Select "calculate" to display the results. The calculation can take several seconds.See also Wave Scatter Diagram Statistics in the User Guide

� W3C Calculation: The W3C calculation requires the Argoss W3C database. This database is not part of Octopus Office 6, but is sold separately.Right Click the "statistics config" in the left pane and select Create W3C Calculation. Enter a name and select OK. Select "Config…" and browse to the Argoss database and Voyage/Route file (See Voyage Section on how to create or add a Voyage/Route file).Change the other settings for the voyage analysis and select OK. Select "Calculate" to start the calculation. Depending on the settings, the calculation can take several hours. See also Statistical W3C Wave Analysis in the User Guide

Frequentely Asked Questions

Q: When I try to open Octopus Office I get the message: CM-Stick Entry not found, Error.A: This happens if the license key is'nt found. Make sure you have plugged in the license key, or make sure the licence key is available by the network.

Q: Octopus Office doesn't see the license stick, however it is plugged into the computer.A: Make sure the following applications have acces to the internet, make sure they are excluded in the firewall settings:

� CodeMeter Runtime Server � CodeMeter Control Center � AMARCON OCTOPUS Office

Q: In the motion RAO, I get very high responses (peaks) for Surge, Sway, and Yaw motions at high speeds.A: The reason for this is the singularity which occurs because the encounter frequency approaches zero.

Q: My heave motion is extremely high, while roll and pitch seem reasonable. What’s going on?A: Maybe you have forgotten to specify your motion reference point in RAO Responses. Default, the motion reference point is equal to (0,0,0), which means (aft, centerline, baseline), see also Definition Coordinate System.

of 56


octupus manual

Documents