navipac cable laying utilities - eivadownload.eiva.dk/online-training/navipac...

NaviPac Cable Laying Utilities

Author : Ole Kristensen

Company : EIVA a/s

Date: April 2012

NaviPac Cable laying

File: C:\USERS\LDA\APPDATA\LOCAL\MICROSOFT\WINDOWS\TEMPORARY INTERNET FILES\CONTENT.OUTLOOK\5F6ADPH2\CABLELAYING.DOC Page 2 of 16

Created by Ole Kristensen Created on: April 2012

Introduction This document gives a short introduction to the catenary functions (for cable and pipe laying)

found in NaviPac as it is – and lists a series of ideas for improvement of the functionality

Contents NaviPac Cable Laying Utilities ................................................................................................. 1

Revision table............................................................................................................................. 2

1 NaviPac 3.8 ........................................................................................................................ 2

1.1 Cable over length ....................................................................................................... 2 1.1.1 Definition in HD .................................................................................................... 4

1.2 Barge run-lines ........................................................................................................... 7 1.3 Catenary monitoring ................................................................................................ 10 1.4 Interface to CMS ...................................................................................................... 12

2 Next generation ................................................................................................................ 12

2.1 NaviCat .................................................................................................................... 13 2.2 Cable Lay ................................................................................................................. 15 2.3 3D Display ............................................................................................................... 15

Revision table

Date Who Comment

10-5-2004 OKR Document created

22-9-2004 OKR Added section 2.2

26-4-2012 OKR Upgraded to version 3.8

More details on HD control

1 NaviPac 3.8 The actual NaviPac version includes a series of functions, which might be used during cable

or pipe laying jobs. Most of these have been designed in close cooperation with various

clients using these features for laying jobs over the last years.

1.1 Cable over length

A typical scenario in laying a cable is that you end up having more cable than the remaining

line – to avoid cutting the cable; a term called “Cable over length” is introduced. Following a

set of rules, a new run-line is created to obtain the wanted length.




Inserting an overlength route may now change each segment:

with the result showed graphically:

A run-line is defined with

a total length of 1248

meters.

But the remaining cable is

1275 meters – ie. Adding

27 meters in total.

The operator may

define route

criteria and

monitor the

changes before

accepting them.




1.1.1 Definition in HD

To activate the feature just follow the steps in Helmsman’s Display:

Edit the runline; in page Segments double click (edit) a STRAIGHT segment (probably the last (or

first) segment); select Main page; select Wave Route (overlength) option and the overlength dialog

will pop up. From here on it’s just a step-by-step procedure.




1.2 Barge run-lines

To obtain the best possible laying operation – especially in the so-called S laying mode – the

touch down point (where the cable/pipe hits the bottom) is a certain distance behind the

laying barge.

Before a job is started, the system is fed with the planned route – which can be used as run-

lines in the helmsman’s Display. But with a layback touch down point there a difference

between the planned route and the route to be followed by the barge.




NaviPac offers a tool called Barge run-lines, where we based on planned route and layback

determines the actual line.

HD with display of planned route




HD with graphical result shown.




1.3 Catenary monitoring

During the laying process, a very important factor is monitoring the total amount of cable out

(in the water column), the tension in the cable and how much the cable is bending.

NaviPac offers a simple catenary monitoring tool – which based on the winch point (where

the cable leaves the barge) and the touch down point (where the cable hit’s the seabed –

monitored with ROV or similar).

It done by defining two objects in NaviPac – one for the leaving point (typically an offset on

the vessel) and one for the touch down point:

A catenary monitoring (up to 5 simultaneously) may now be defined:




The optimal calculation is obtained by inputting weight of catenary cable.

The result may be monitored (any computer on the network) as alphanumerical displays:

The most interesting value to watch for the operator is normally the Vertical Angle (Theta) that is the angle of

the catenary curve.

Horizontal Distance (X):

Definition of calculations:

- Name

- Input parameters

- Leave point

- Touch down point




This field gives the horizontal distance between the two points.

Vertical Distance (Y):

This field gives the vertical distance between the two points.

Vertical Angle (Theta):

Hold the vertical angle of the catenary curve.

Length of Catenary (L):

Hold the computed length of the catenary curve.

Min radius of catenary curve ®:

The computed min. radius of the catenary curve

Horizontal Tension (H):

If a unit weight is specified the horizontal tension is shown here.

Vertical Tension (V):

If a unit weight is specified the vertical tension is shown here.

Total Tension (T):

If a unit weight is specified the sum of vertical and horizontal tension is shown here.

1.4 Interface to CMS

NaviPac includes, if operated in TMS/RigMove mode, an interface to a special Stolt Offshore

Catenary Monitoring System (Halliburton Subsea CMS )

It output’s information about barge and anchor locations, and offers the receiving program

sufficient information to document behavior of the anchor chains. Details on formats can be

obtained from NaviPac manuals.

2 Next generation During the use of NaviPac for barge and laying operations, and lot of new ideas has been

raised from a.o. Subsea7, C&C Technology and Capital Signal, and we are based on these

input’s working of projects to include these ideas in standard NaviPac operations.

This has resulted in a CableLay add-on to NaviPac developed in cooperation with the Danish

company JD Contractors.

C/B Henry P. Lading




The system is build around NaviPac, as all sensor interfacing and recording takes place here.

The system requires special data input of

- Cable output angle

- Cable length

- Cable tension

Based on those inputs the system calculates the catenary curve in the water and estimates the

touchdown point.

Please note that cable interfacing is most often different for each vessel, so tailor-making

must be expected!

2.1 NaviCat

The brain in the system is the EIVA catenary solution, which performs a full 3D calculation

of the cable in the water column and along the seabed.




The catenary model is based on a 3D particle system and allows full computation of forces

along the chain. This model can be expanded to include external forces such as current.

The system loads terrain information (DTM, profile or fixed depth) and used this for the

touchdown estimation and cable curvature calculations.




2.2 Cable Lay

The Cable Lay module is program running beside NaviPac (same pc or remote) and it gives

the cable operator the needed displays to monitor cable speed, angle, bending radius etc.

This module is also responsible for the cable amounting, and thus a very important tool.

2.3 3D Display

The cable lay scenario can be connected to NaviPac Online3D, and thus give a user friendly

visualization of the entire project:

navipac cable laying utilities - eivadownload.eiva.dk/online-training/navipac...

Documents