sea trial procedure

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T&

R Bulletin3-47


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SNAME Technical and Research Bulletin 3-47 (2015)Guide for Sea Trials


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TECHNICAL AND RESEARCH BULLETIN 3-47 (2015)

GUIDE FOR SEA TRIALS (PROGRESSIVE SPEED,MANEUVERING, AND ENDURANCE)

Prepared by

Ship Production and Machinery Committee Working Groups

In conjunction with the

SHIPS MACHINERY COMMITTEE

August 2015


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This Bulletin was prepared under direction from the Ships Machinery Committee

for

THE SOCIETY OF NAVAL ARCHITECTS AND MARINE ENGINEERSTECHNICAL AND RESEARCH PROGRAM

Prepared by a Working Group of Ship Production and Machinery Committee WorkingGroups and Volunteers

Mr. Frederick (“Rick) H. Ashcroft, Working Group Chair

Mr. Roderick BarrMr. Robert BehrMr. Jeffrey BohnMr. Karl Briers

Mr. Christopher CableMr. Bruce CowperMr. Brice FuchsMr. Soren HansonDr, Wei-Yuan HwangCaptain Tom KnierimMr. Darrell Milburn

Mr. Jan Otto de KatMr. Frans QuadvliegMr. J. Ryan RobertsMr. Eugene Van Rynbach

Mr. Mark ShanksMr. Gene ShuckMr. Malcolm Whitford

Reviewed and Approved by:SHIPS MACHINERY COMMITTEE

M Ri h d D l i C itt Ch i


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AbstractThis guide covers progressive speed, maneuvering, and endurance sea trials of self-propelled surfaceships displacing 300 tonnes or more, powered by hydrocarbon fuels such as petroleum, natural gas or

bio fuel, and driven by diesel or Otto cycle engines, gas turbine, or electric motors. References aremade to applicable international standards. This Bulletin does not cover dock trials, tests, ordemonstrations that can be conducted dockside, which are covered in SNAME T&R Bulletin 3-39,Guide for Shop and Installation Tests.

This Guide is intended to assist users in applying IMO maneuvering standards and to allow theowner, designer and builder to rate the vessel’s ma neuvering performance relative to statistical data ofvessel maneuvering characteristics. The Guide summarizes the procedures to be used in assessing avessel’s maneuvering performa nce.

SNAME welcomes comments and suggestions for improvement of this Guide. Comments orsuggestions can be sent electronically to [email protected].


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Preface

This document evolved from the worldwide use of The Society of Naval Architects and MarineEngineers' (SNAME) Code for Sea Trials - 1973 (Technical and Research Code C-2) dealing with seatrials. The Ships' Machinery Committee of the Society's Technical and Research Program assignedthe initial expansion and update of the document to Panel M-19 (Ship Trials) with the assistance ofPanel H-10 (Ship Controllability). At that time the document was altered from being a "code" to

being a "guide". The resulting Guide was published in 1989. Continuing its popularity andfrequency of citation in ship specifications, the National Shipbuilding Research Program (NSRP)

provided support for the 2015 update of the guide. While the basic guidelines remain solid, updateswere long overdue in recognizing technological advances in sea trial instrumentation, the changefrom steam propulsion to diesel and other modern propulsion systems, recognition of othertechnological advances and updates of the International Maritime Organization (IMO) and otherstandards organizations regarding a number of areas including ship maneuverability, instrumentation,and environmental issues. Representatives from the SNAME’s Ship Production Committee., NSRP,and volunteers including senior marine engineers and naval architects from all fields of interest

provided comments. The consensus of these efforts were included in the guide as approved andissued. The final draft was reviewed by the Ships' Machinery Committee with plans to undergo a

periodic updating process that would provide for regular updating and improvements to the guide.

The basic concept followed in this guide is to provide information on a sufficient variety of sea trialsand tests to enable an owner or acceptance authority to choose those suitable for the type of ship andoperation involved. Positive contractual invocation of specific individual trials is recommendedrather than having them invoked as a package without proper consideration. This avoids burdening

the industry with expensive trials not needed by the owner.

The guide provides a list of those trials recommended as necessary to demonstrate that the ship as built and delivered will perform as specified. Absence of an at-sea test or trial from those


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forms for the presentation of sea trial reports. Appendices include definitions of terms peculiar to seatrials as they are employed in the guide and a procedure for adjusting turning circle test data for drift.

Disclaimers

This guide is intended to be advisory only. There is no implication of warranty by SNAME thatsuccessful performance of the recommended trials will ensure that a ship will comply with therequirements of the contract specifications, regulatory bodies or classification societies, or that it will

perform satisfactorily and safely in service.

The opinions or assertions of the authors are not to be construed as official or reflecting the views ofSNAME or any government agency.

It is understood and agreed that nothing expressed herein is intended or shall be construed to give any person, firm, or corporation any right, remedy, or claim against SNAME or any of its officers ormembers.

Acknowledgements

The Committee gratefully acknowledges the contributions of the members of the Society, industry,and government who have been generous in assisting the working group in accomplishing its task.The National Shipbuilding Research Program (NSRP) is recognized for providing funding thatallowed for active involvement of shipbuilding professionals and completion of this update in a

timely and meaningful manner. The American Bureau of Shipping is recognized for allowing anumber of figures from their publications available for the update. Student Samantha Adornati fromStevens Institutes under the direction of Professor Raju Datla is recognized for drafting and/orrevising figures in the guide.


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Page

TABLE OF CONTENTS

Abstract ....................................................................................................................................................

Preface ......................................................................................................................................................

Disclaimers .............................................................................................................................................. i

Acknowledgements ................................................................................................................................. i

TABLE OF CONTENTS ...................................................................................................................... iii

LIST OF FIGURES ............................................................................................................................... ix

LIST OF TABLES ................................................................................................................................ ix

1.0 INTRODUCTION ............................................................................................................................ 1

1.1 SUPERSESSION ......................................................................................................................... 1

1.2 ORIGIN ........................................................................................................................................ 1

1.3 PURPOSE .................................................................................................................................... 1

1.4 SCOPE.......................................................................................................................................... 1

1.5 TRIAL OBJECTIVES .................................................................................................................. 1

1.5.1 Demonstration of Operability ................................................................................................ 1

1.5.2 Demonstration of Performance .............................................................................................. 2

1.5.3 Demonstration of Endurance ................................................................................................. 2 1.5.4 Demonstration of Economy ................................................................................................... 2

1.5.5 Demonstration of Energy Efficiency Design Index (EEDI) .................................................. 2


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1.9.2 Pre-Arrangements .................................................................................................................. 7

1.10 PRE-TRIAL CHECK LIST ........................................................................................................ 8 1.11 BUILDERS' TRIALS ................................................................................................................. 8

2.0 PROPULSION PLANT TRIALS ..................................................................................................... 9

2.1 GENERAL ................................................................................................................................... 9

2.1.1 Scope of This Section ............................................................................................................ 9

2.1.2 Specific Objectives ................................................................................................................ 9

2.1.3 Pre-Trial Agreements ............................................................................................................ 9 2.1.4 Trial Preparations .................................................................................................................. 9

2.1.5 Trial Duration ...................................................................................................................... 10

2.2 PROPULSION PLANT ECONOMY TRIALS ......................................................................... 13

2.2.1 Purpose ................................................................................................................................ 13

2.2.2 Operating Conditions ........................................................................................................... 13

2.2.3 Frequency of Observations .................................................................................................. 13

2.2.4 Communication ................................................................................................................... 13

2.2.5 Measurements and Instrumentation ..................................................................................... 13

2.2.6 Fuel Rate Data Required ..................................................................................................... 14

2.2.7 Trial Report ......................................................................................................................... 15

2.3 PROPULSION PLANT AHEAD ENDURANCE TRIALS ...................................................... 15

2.3.1 Purpose ................................................................................................................................ 15

2.3.2 Measurements and Instrumentation ..................................................................................... 15

2.3.3 Trial Report ......................................................................................................................... 16


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2.6 SPECIAL CONSIDERATIONS FOR GAS TURBINE PROPULSION PLANT TRIALS ...... 18

2.6.1 Auxiliary Components ......................................................................................................... 18 2.6.2 Fuel Rate Data Required ..................................................................................................... 18

2.6.3 Power ................................................................................................................................... 19

2.6.4 Trial Data and Report .......................................................................................................... 19

2.7 SPECIAL CONSIDERATIONS FOR ELECTRIC DRIVE PROPULSION PLANT TRIALS 19

2.7.1 Auxiliary Components ......................................................................................................... 19

2.7.2 Power ................................................................................................................................... 19 2.7.3 Trial Data and Report .......................................................................................................... 19

2.8 CENTRALIZED PROPULSION CONTROL SYSTEM TEST ................................................ 20

2.8.1 Purpose ................................................................................................................................ 20

2.8.2 Procedure ............................................................................................................................. 20

2.8.3 Trial Report ......................................................................................................................... 20

3.0 MANEUVERING AND SPECIAL TESTS ................................................................................... 23

3.1 SELECTION OF TESTS ........................................................................................................... 23

3.2 PREPARATION ........................................................................................................................ 24

3.3 REPORTS .................................................................................................................................. 24

3.4 AHEAD STEERING .................................................................................................................. 24

3.5 ASTERN STEERING ................................................................................................................ 27

3.6 AUXILIARY MEANS OF STEERING..................................................................................... 27

3.7 TURNING CIRCLES ................................................................................................................. 27

3.8 "Z" MANEUVER* ..................................................................................................................... 32


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3.19 NAVIGATION EQUIPMENT ................................................................................................. 53

4.0 STANDARDIZATION TRIALS ................................................................................................... 54 4.1 PURPOSE .................................................................................................................................. 54

4.2 GENERAL PLAN ...................................................................................................................... 54

4.3 TRIAL AREA ............................................................................................................................ 54

4.3.1 GNSS ................................................................................................................................... 54

4.3.2 Depth of Water .................................................................................................................... 54

4.4 WIND AND SEA ....................................................................................................................... 54 4.5 NUMBER OF SPEED POINTS ................................................................................................. 55

4.6 COURSE SELECTION.............................................................................................................. 55

4.6.1 Length of Runs .................................................................................................................... 55

4.6.2 Number of Runs .................................................................................................................. 55

4.7 OPERATION OF THE SHIP ..................................................................................................... 55

4.8 DATA REQUIREMENTS ......................................................................................................... 56

STANDARDIZATION RESULTS ................................................................................................................ 57

4.9 ORGANIZATION OF OBSERVERS ....................................................................................... 58

4.10 INSTRUMENTATION FOR STANDARDIZATION DATA ................................................ 58

4.11 COORDINATION PROCEDURE ........................................................................................... 58

4.12 TOLERANCES AND LIMITS ................................................................................................ 58

4.13 DATA REDUCTION ............................................................................................................... 59

4.14 CORRECTIONS ...................................................................................................................... 59

5.0 INSTRUMENTS AND APPARATUS FOR SHIP'S TRIALS ...................................................... 60


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5.3.5 Barometers ........................................................................................................................... 62

5.3.6 Manometers ......................................................................................................................... 62 5.3.7 Manometers for Flow Measurement.................................................................................... 63

5.3.8 Liquid Columns ................................................................................................................... 63

5.3.9 Zimmerli Gage..................................................................................................................... 63

5.3.10 Absolute Pressure Gages ................................................................................................... 63

5.3.11 Gage Protection from Pressure Pulsation .......................................................................... 63

5.3.12 Further Information ........................................................................................................... 63 5.4 FLOW MEASUREMENTS ....................................................................................................... 63

5.4.1 Types of Instruments ........................................................................................................... 63

5.4.2 Positive Displacement Flow Meters .................................................................................... 63

5.4.3 Meter Installation for Precise Measurements ...................................................................... 64

5.4.4 Orifice Plate, Flow Nozzle, and Venturi Tube .................................................................... 64

5.4.5 Indicating and Recording Mechanism for Orifice Plate, Flow Nozzle, and Venturi Tube . 64

5.5 TORQUE AND POWER MEASUREMENTS .......................................................................... 65

5.5.1 Power Determined Indirectly............................................................................................... 65

5.5.2 Power Determined From Torque Measurements ................................................................. 65

5.5.3 Shaft Torsionmeters ............................................................................................................. 65

5.6 SHAFT-POWER METERS ....................................................................................................... 66

5.7 SHAFT THRUSTMETERS ....................................................................................................... 66

5.7.1 Purpose of Thrustmeter ....................................................................................................... 66

5.7.2 Useful Installations .............................................................................................................. 66

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5.12 WIND SPEED AND DIRECTION MEASUREMENTS ........................................................ 70

5.12.1 Cup Anemometer ............................................................................................................... 70 5.12.2 Indicators ........................................................................................................................... 70

5.12.3 Biram Anemometer ........................................................................................................... 70

5.12.4 Direct-Reading Anemometer ............................................................................................. 70

5.12.5 Deflecting-Vane Anemometer ........................................................................................... 70

5.12.6 Wind Direction Indicator ................................................................................................... 70

5.12.7 Combination Indicators ..................................................................................................... 71 5.12.8 Locating Sensors ............................................................................................................... 71

5.12.9 Ultrasonic Wind Sensors ................................................................................................... 71

5.13 TRACKING SYSTEMS .......................................................................................................... 71

5.14 TIME MEASUREMENTS ....................................................................................................... 71

5.14.1 Types of Instruments ......................................................................................................... 71

5.14.2 Synchronizing Clocks ........................................................................................................ 71

5.14.3 Stop Watches ..................................................................................................................... 71

5.14.4 Electric Timers and Clocks ............................................................................................... 71

5.14.5 Recorders ........................................................................................................................... 72

6.0 TRIAL DATA AND REPORT ...................................................................................................... 73

6.1 GENERAL ................................................................................................................................. 73

6.2 DATA PLAN ............................................................................................................................. 73

6.3 DATA CREW TRAINING ........................................................................................................ 73

6.4 MANEUVERING TRIALS AND SPECIAL TESTS ................................................................ 74


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A.4 STANDARDIZATION TRIALS .............................................................................................. 91

A.5 INSTRUMENTATION ............................................................................................................. 92 APPENDIX B CORRECTING TURNING CIRCLE PLOTS FOR DRIFT........................................ 93

B.1 PRINCIPLE ............................................................................................................................... 93

B.2 PLOTTING OVERGROUND TRACK .................................................................................... 93

B.3 DETERMINATION OF DRIFT ................................................................................................ 93

B.4 DETERMINATION OF DRIFT RATE .................................................................................... 94

B.5 PLOTTING THE DRIFT CORRECTED TURNING CIRCLE ................................................ 94 B.6 DETERMINATION OF TURNING CIRCLE DIMENSIONS ................................................ 94

B.7 CALCULATION OF DRIFT RATE IN KNOTS ..................................................................... 94

LIST OF FIGURES

Figure 1 Turning Circle Definitions (Courtesy of ABS) ...................................................................... 29 Figure 2 Turning Circle Test ............................................................................................................... 30 Figure 3 "Z" Maneuver Test (Courtesy of ABS) .................................................................................. 33 Figure 4 Initial Turning Test, Change of Heading Plot ....................................................................... 36 Figure 5 Initial Turning Test, Plot of Change of Turning Rate ........................................................... 36 Figure 6 Pullout Test (Courtesy of ABS) ............................................................................................ 38

Figure 7 Direct Spiral Test .................................................................................................................. 43 Figure 8 Reverse Spiral Test (Courtesy of ABS) ................................................................................ 44 Figure 9 Crash Stop Test (Courtesy of ABS ....................................................................................... 49 Figure 10 Typical Standardization Course .......................................................................................... 56


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Table 14 Low Speed Controllability Maneuvering Test Data ............................................................. 52 Table 15 Slow Steaming Ability ......................................................................................................... 53 Table 16 Standardization Trials Data .................................................................................................. 57 Table 17 Standardization Trial Tolerances and Limits ....................................................................... 58 Table 18 Internal Combustion engine Propulsion Plant Economy Test ............................................... 75 Table 19 Gas Turbine Plant Economy Test Data ................................................................................ 76 Table 20 Propulsion Plant Data (Includes 10 Data Sheets) ................................................................. 80 Table 21 Propulsion Plant Data - Sheet 2 Diesel................................................................................. 81 Table 22 Propulsion Plant Data - Diesel (Cont2) ................................................................................ 83 Table 23 Propulsion Plant Data - Electric Drive ................................................................................. 84

Table 24 Propulsion Plant Data - Gas Turbine .................................................................................... 84 Table 25 Propulsion Plant Data - Gas Turbine (Cont) ........................................................................ 86


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1.0 INTRODUCTION

1.1 SUPERSESSION

This Society of Naval Architects and Marine Engineers (SNAME) T&R Bulletin 3-47(2015) " Guide for Sea Trials (Progressive Speed, Maneuvering, and Endurance)" supersedes T&R Bulletin 3-47Guide for Sea Trials 1989 .

1.2 ORIGIN

This Guide was developed by updating the 1989 Guide for Sea Trials-1989 that was produced bySNAME Panel M-19 (Ship Trials) with assistance from Panel H-10 (Ship Controllability) andapproved by the Ships’ Machinery Committee of SNAME . This update effort was supported byfunding from the National Shipbuilding Research Program. Those contributing to the update includea variety of volunteers from organizations including shipbuilders, ship owners, ship designers,operators, Classification Society, Government organizations and others. Publications of otherSNAME Technical Panels, Classification Societies, and international standards organizations wereconsulted to check compatibility and various sources in the technical literature were researched foradvances and current trends. The recommendations include incorporation of ISO 15016.2 Guidelines

for the assessment of speed and power performance by analysis of speed trial data and IMOResolution MSC.137 (76), Standards for Ship Maneuverability .

1.3 PURPOSE

The purpose of the Guide is to provide ship owners, designers, operators, and builders with definitiveinformation on ship trials to form a basis for contractual agreement.

1.4 SCOPEThe Guide covers sea trials of self-propelled surface ships, commercial or naval, displacing 300tonnes or more, powered by hydrocarbon fuels such as petroleum, natural gas and bio fuels and


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1.5.2 Demonstration of Performance

The attainment of maximum contract levels of power or speed is particularly important for the firstship of a class to verify the adequacy of the design of the propulsion plant and its supportingauxiliaries.

1.5.3 Demonstration of EnduranceDemonstration of ability to maintain maximum power and speed for sufficient time to developequilibrium conditions and to operate at those conditions for the prescribed period without failure ofsystem components is important for every ship. It is assumed that the ability to operate in this mannerindefinitely, or for the design life, will thereby have been demonstrated, since any functionalinadequacies will have been made evident by this and other trial operations.

1.5.4 Demonstration of Economy Demonstration of the contract specific fuel consumption is mandatory when there is a penaltyinvolved or when required by the ship's specifications. Attainment of the best possible fuelconsumption is important when there is a bonus involved. When neither are involved it is stillrequired to determine fuel rate for the first of a class to verify design and for subsequent ships toverify proper operability of the energy conversion system.

1.5.5 Demonstration of Energy Efficiency Design Index (EEDI)Demonstration of the vessel's EEDI characteristics is important to verify its relative rating of energyefficiency (see ISO 15016.2 for details on EEDI).

1.5.6 Demonstration of Controllability

Demonstration that a vessel has maneuvering qualities permitting course keeping, turning, checkingturns, operating at acceptably slow speeds, and stopping in a satisfactory manner is important for safeoperations of a ship in open and restricted areas.

1.5.7 Establishment of Operating Performance Baseline

It is desirable to establish a performance baseline (in the form of data sets) for a new class of shipsand to a lesser degree for individual ships so that ship operators will have a standard with which to


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of innovative features or to advance the state of the shipbuilding art may be called for. In such casesit is important that the design authorities who will use the data specify requirements in detail,including instrumentation, operating conditions, and procedures. The IMO, for instance, gathers dataon ship maneuverability in its developing and refining of standards and has detailed specificmaneuvers that are included herein.

1.5.10 Classification and Safety Requirements

Classification societies and safety authorities often require demonstration of equipment and systemswhich affect safety of the ship, its cargo or its crew.

1.6 SHIP AND ENVIRONMENTAL CONDITIONS

Proper ship and environmental conditions during trials are often critical for achieving useful results.

1.6.1 Sea Trial Loading Conditions

Where possible, trials will be carried out in the design load draft condition.

However, due to limitations in ballast capacity, Contractor's Sea Trials will frequently be performedat other drafts. Separate trials in the ballast condition may be required. For uniformity in selecting

ballast drafts for oil tankers, consideration should be given to those specified by IMO 73/78MARPOL for designed ballast draft capability for tankers.In all cases, the fore and aft drafts at the time of the trial must be recorded. For ships not providedwith full draft capability via ballasting, trial drafts will not approximate maximum design draft, anddemonstrations of capabilities that are draft dependent, such as ship's speed and maneuverability, areof limited value. In such cases it is advisable to specify model tests at anticipated trial drafts as wellas maximum design draft, as without such tests, extrapolation of trial results depends on uncertainestimates. Trials should be conducted at drafts as close as practicable to the model test conditions. Inthe absence of model test data as a reference point, standardization results at other than the maximumdesign draft is not recommended.

1.6.2 Water Depth

The most demanding operational requirements for many ships are met in shallow water during coastal


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H = Water Depth (m)

Am = Midship Section Area (m2

)V = ship's Speed (m/sec)

1.6.3 Wind, Waves, and CurrentsThe uncontrollable environmental conditions of wind, waves, and currents can significantly influencethe results of all underway trials. These effects are also difficult to account for. Trials should thus beheld in the calmest weather conditions available. Wind direction and speed should be noted at thestart of each test, so that the effects can be studied and corrections applied. Currents, wave, and swellconditions and their change should also be noted.

Sea State 4 with a significant wave height of up to 2.5 m, should be avoided. Sea State 3 with asignificant wave height of up to 1.25 m, should be avoided for ships under 152.4 m (500 feet) inlength.

Wind speeds of more than 10 m/second (19.4 knots or nmi/hr) should be avoided. Maneuveringspiral tests and slow speed trials are particularly sensitive to wind and currents. Wind speed should

not exceed around 5 m/second (9.7 knots) to assure useful results from such trials.1.7 LIST OF TRIALS AND SELECTION

Blanket invocation of this Guide is not intended. Sufficient trials and tests are included to enable theuser to select a sea trial or test of any degree of complexity desired. Invocation of the total Guide,however, without regard to the objectives to be served or the utility of data obtained would result inexcessive costs with little value. Users should study the Guide, and then when writing their ship’sspecification specify by paragraph number in this guide the trials and tests required to meet their

objectives.Lists of trials and tests recommended for first-of-a-class and follow-on ships are provided forconvenience. If this Guide is invoked by contract, all of the recommended trials and tests are to beconducted except for those specifically deleted and trials or tests marked "If Elected" are to be


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Table 1 Recommended Trials

Name RecommendationGuide

Paragraph

Economy Trials First of a Class only 2.2

Endurance Trials All Ships 2.3

Astern Trial All Ships 2.4Diesel Propulsion If Elected 2.5

Gas Turbine Propulsion If Elected 2.6

Electric Drive If Elected 2.7

Centralized Propulsion Control System All Ships 2.8

Ahead Steering All Ships 3.4

Astern Steering All Ships 3.5

Auxiliary Means of Steering All Ships 3.6

Turning Circles First of a Class only 3.7

Z Maneuver First of a Class only 3.8

Initial Turning First of a Class only (1) 3.9

Pullout First of a Class only 3.10

Direct Spiral First of a Class only 3.11

Reverse Spiral If Elected (2) 3.12Thruster First of a Class only 3.13

Quick Reversal from Ahead to Astern All Ships 3.14


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Bulletin 3-47 does not address noise and vibration measurements which are generally not performedon sea trials. It is recommended that these tests, however, should be coordinated with related aspectsof the sea trials program. Ahead endurance trials offer an opportunity for concurrent measurementsfor airborne noise.

1.8 RECOGNITION OF UNCERTAINTY

Although ship designers, builders, and trial personnel may exercise greatest diligence in pursuingtheir art at the most advanced state, there is inherent in the measurement of ship performance anunavoidable uncertainty. No measurement is perfect and shipboard conditions preclude the use of themost precise techniques. Since the major ship performance parameters involve measurement of manyfluctuating quantities, each with an element of uncertainty, the cumulative effect might beconsiderable. By applying probability techniques to the degree of fluctuation and the inherent

precision of the instruments involved, including their calibration, it is possible to identify the degreeof certainty with which a ship's performance can be determined.

It is important that all parties to a ship construction program recognize the uncertainty of trial resultsand take it into consideration when establishing performance target/bonus/penalty levels.

Knowledge of how much the precision of the individual measurements affects the performance

determination and the range of precision available for the instruments involved enables the trial planner to make an intelligent and economic decision on instrumentation. The reader is referred toISO 15016.2 Section 5.1 for a discussion on required accuracy for torque measurements.

1.9 PLANNING

From award of a contract until delivery of the official trial report, sea trials require continual planning. Trial instrumentation requirements should be incorporated in design; prearrangements may be required for obtaining and calibrating trial instruments; trial readiness checks should be included in

production planning; trial data acquisition, processing, and reporting systems should be developed,installed, and checked; instructions and procedures should be developed for trial operating and datacrews; and these crews should be trained.

A prerequisite to all planning is a clear understanding as to the tests and trials to be conducted the


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(b) If special trial fuel meters are to be installed, systems should be designed toaccommodate them.

(c) If special gages, thermometers or orifices are to be installed, sensing points should beselected and the necessary fittings, wells, or flanges provided.

(d) If fuel samples are to be taken during trials, a sampling connection or method should be provided.

1.9.2 Pre-Arrangements(a) If the shaft is to be calibrated, the shafting production schedule should be adjusted to

provide for calibration availability; the torsionmeter should be requested if furnished bythe government, or procured or overhauled if furnished by the contractor; the torqueinggear should be made ready, the calibration accomplished and the instrument factorsestablished. Unless permanent torque meters are installed, this measurement is doneusing strain gages installed just prior to trials and calibrated using shunt resistors.Material properties of the shaft need to be provided by the manufacturer or assumed

based on ISO 15016.2

(b) Plant operating conditions and modes; ship draft conditions; and shaft power levels

should be established for each trial and the owner's concurrence obtained.(c) Plant operating and ship's ballasting and de-ballasting instructions should be prepared and

distributed to trial crew supervisors.

(d) Signal system should be designed and installed.

(e) Correction factors should be obtained and the concurrence of owner’s technicalrepresentatives established.

(f) Data instructions and station bill should be prepared and distributed.

(g) Special trial instruments should be installed and all instruments which will provide trialdata calibrated, “red line” settings made and “water legs” measured. Sensor calibrationshould include addressing remote or indirect means the sensor relies on for accuracy.


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1.10 PRE-TRIAL CHECK LIST

So many items are involved in determining readiness for sea trials that it is virtually necessary to usea check list. Such a list should include all machinery, equipment, and trials to be tested and pretestsor other preparations necessary to perform the tests to assure readiness.

1.11 BUILDERS' TRIALS

If builders' trials or runs are to be conducted, they should be specified. If data for any portion of thetrial or runs is to be presented for acceptance, the owners, acceptance authorities, and involvedregulatory bodies should be notified in advance. If builder ’s trials are not specified, they are to be atthe discretion of the builder for any purpose, including any of the following:

Checking the operation of the machinery installation and the trial equipment. Training the operating and trial personnel. Making adjustments to the propulsion plant to establish proper operation. Determination of ability to meet performance requirements.


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2.0 PROPULSION PLANT TRIALS

2.1 GENERAL

2.1.1 Scope of This SectionThis section contains recommendations for conducting internal combustion engine, gas turbine, andintegrated electric propulsion plant trials with the ship underway under specified conditions. The

propulsion plant is considered to include propulsion plant machinery, all auxiliaries and systems

required for its operation and other such apparatus as are necessary for the operation of the ship undertrial conditions. The instructions herein are intended to cover testing of the propulsion plant as anintegrated system underway and do not cover ship or shop tests of individual equipment items, docktrials, or dockside tests required by specifications or regulatory bodies, unless prescribed herein asincidental to the trials.

Specific requirements for these types of propulsion plants can be found beginning with paragraph 2.2.

2.1.2 Specific Objectives

Specific objectives of propulsion plant trials may be one or more of the following: To demonstrate satisfactory operation of the propulsion plant for a specified period of time at

specified power, usually maximum design power. To determine the rate of fuel consumption of the plant when operating at specified shaft

power and other specified operating conditions. To determine performance characteristics of the machinery plant or components thereof, as

agreed. To demonstrate satisfactory operation of propulsion plant controls from all stations.

To obtain propulsion plant data for future use in evaluating service performance. Note that the power level of the propulsion plant may be specified in terms of revolutions per minutewhen trial draft or other conditions make full power unattainable within shaft speed limitations.


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Calibration of trial fuel meters. Wh ere ship’s meters are used as trial or trial back -upinstrumentation, they should also be calibrated.

Calibration of special gages and meters. Records of calibrations should be available prior totrials and carried onboard during trials.

Installation of trial equipment as required. Ascertaining that all machinery and equipment is in proper working condition. Preparation of the trial ballasting plan to provide the prescribed submergence of the propeller. Control and records of fuel onboard to provide for trials a homogeneous, known, supply. Analysis of the fuel to be burned including heating value, specific gravity, viscosity

characteristics, and other pertinent properties.

2.1.5 Trial Duration

Duration of each Propulsion Plant Trial should be as set forth in Table 2 and Table 3 unless otherwisespecified or agreed.

Unless otherwise agreed, any run, which has been interrupted by machinery casualties necessitatingslowing down or stopping, should be entirely rerun. If the interruption of a run is due to operatingerror or maneuvering from the bridge due to traffic or other safety situations, only the disrupted

portion of the run need be repeated.


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Table 2 Recommendations for Internal Combustion Propulsion Plant Trials

TRIAL Ahead Endurance c Astern Endurance Economy

DURATION 4 hours a

30 Minutes 4 hoursa

POWER LEVEL Max ContinuousRating

Max AsternContinuous Rating b

SpecifiedContinuous ServiceRating

CRITICAL MEASUREMENTS Power Torque/RPM Power Level & FuelConsumption

INTERVAL FOR CRITICALMEASUREMENTS

15 Minutes 10 Minutes 15 Minutes

SUPPORTING DATA (Aspertinent)

Torque Torque Same as AheadEndurance

RPM RPM Plus: Aux LoadProp Pitch Prop Pitch FuelPRPLS Motor KWd PRPLS Motor KWd PRPLS Motor KWd Rack Position Rack PositionMax Cylinder FiringPressure

Fuel sample forheating valueanalysisAir Intake Temps

PLANT CONTROLPARAMETER

Power or RPM Torque RPM Power or RPM

MEANS OF CONTROL Remote Control Remote Control Remote Control


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Table 3 Recommendations for Gas Turbine Propulsion Plant Trials

TRIAL Ahead Endurance Astern Endurance Economy

DURATION 4 hours a 30 Minutes 4 hours a

POWER LEVEL Max Designa Max Continuous b Service a

CRITICAL MEASUREMENTS Power Torque/RPM Power Level & Fuel

ConsumpINTERVAL FOR CRITICALMEASUREMENTS

15 Minutes 10 Minutes 15 Minutes

SUPPORTING DATA (As pertinent) Torque Torque Same as AheadEndurance

RPM RPM Plus: Aux Load

Prop Pitch Prop Pitch Fuel

PRPLS Motor KWc PRPLS Motor KWc PRPLS Motor KWc Exhaust Temp Exhaust Press Air Intake Temps

DEVIATION OF CRITICALMEASUREMENT AVERAGESFROM LEVEL SPECIFIED

Plus Mfg's Lim Plus Mfg's Lim Plus 5%

Minus 2% Minus 10% Minus 5%

FLUCTUATION OF INDIVIDUALDATA ITEM FROM AVERAGE FOR

CRITICAL MEASUREMENT

Plus 5% Plus Mfg's Lim Plus 5%

Minus 5% Minus 20% Minus 5%

PLANT CONTROL PARAMETER Power or RPM Torque RPM Power or RPM

MEANS OF CONTROL Remote Control Remote Control Remote Control


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2.2 PROPULSION PLANT ECONOMY TRIALS2.2.1 PurposeThe primary purpose of Economy Trials is to determine fuel consumption. An ancillary purpose is toestablish an RPM/SHP relationship under trial conditions.

2.2.2 Operating ConditionsUniform operating conditions should be maintained throughout each trial run. To establish steady

operating conditions for economy measurements, a period of warming up or adjustments should beallowed prior to trial runs. Steady-state conditions should be proven prior to starting economy trials.

Helm changes should be held to a minimum and course changes should be made with no more than 5degrees rudder. The test director must be informed when ship navigation necessitates the change inship’s speed or the use of more than 5 degrees rudder. An announcement should be made to suspendand/or resume affected measurements when under these conditions.

2.2.3 Frequency of ObservationsUnless otherwise agreed, observations and instrument readings should be taken at fifteen minuteintervals. Readings of torque or shaft power should be taken as required for producing, as nearly as is

practicable, a continuous record. Digital data acquisition should utilize appropriate data samplingtechniques which will be averaged at 15-minute intervals. See Tables 2 and 3 for reading intervalsfor important data.

2.2.4 CommunicationVisual and audible signaling should be used onboard to announce and enable accurately marking the

beginning and end of runs and to synchronize data taking. Hand- held radios and ship’s telephone or

public address systems can be used, but should be controlled from a central station.2.2.5 Measurements and Instrumentation

(a) General


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Measurements of auxiliary electric power should be made by ship’s instruments unlessotherwise agreed. For major ampere loads, clamp type ammeters should be utilized todetermine loads where ammeters are not fitted.

For ships on which hotel loads are relatively large, provision for separate measurementsof total auxiliary machinery loads and hotel loads is recommended.

(c) Revolutions.

Accurate and reliable trial shaft counters suitably interfaced with the trial signal systemor data reduction system should be installed and checked out prior to the start of the seatrials. For details on shaft revolution counters, see Section 5.0, Instruments andApparatus for Ship’s Trials.

(d) Fuel Measurements.

Measurements of fuel quantity should be made by flow rate meters, which should becalibrated before and after trials and the calibration correction applied to the observedtrial data. For further details on the installation of trial fuel meters, refer to Section 5.0,Instruments and Apparatus for Ship’s Trials.

(e) Other Measurements.

Measurements of pressure and temperature which materially affect trial results should beobtained from calibrated test gages and thermometers installed for the trial. Data fromship's gages, thermometers and instruments may be used for trial purposes provided theseinstruments have been calibrated and set to read correctly in the operating range.

Acceptable instruments for time measurements are described in Section 5.0, Instrumentsand Apparatus for Ship’s Trials.

Measurements of water flow, when required, should be made with calibrated water

meters installed for this purpose. Ship's installed meters may be used if calibrated.Modern engine electronic control systems are another resource of performance dataonboard. Information from these systems can be useful during trials if high accuracy


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Note: Fuel Properties should be determined by post trial analysis of a thorough mix of fuel samplestaken at a minimum of four equally spaced intervals during the run.

Also note that if Coriolis type meters are used, the fuel consumption rate can be obtained directly asmass per unit time so that d) and e) above are not required.

2.2.7 Trial ReportSee tables in Section 6.0, Trial Data and Report.

2.3 PROPULSION PLANT AHEAD ENDURANCE TRIALS

2.3.1 PurposeThe primary purpose of Ahead Endurance Trials is to demonstrate satisfactory ahead operation of the

propulsion plant at specified operating conditions as contractually required or agreed. This shouldinclude specific shaft power or revolutions per minute for a prescribed period of time.

Since satisfactory operation and performance of the machinery plant is equally essential forendurance and economy trials, they may be conducted concurrently when specifications for both arethe same for shaft power, period of run time, and fuel. For Endurance Trials the emphasis is onattaining and sustaining the required power level. Fuel rate is a secondary interest. For Economy

Trials the fuel and power data are the essentials. Other data including possible auxiliary load levelsare used to explain results to correct for off-standard conditions.

Sometimes Endurance Trials are specified to include a demonstration of satisfactory operation of the propulsion plant under service conditions during a specified voyage of the ship. Such trials and thedetails thereof are subject to agreement between the parties involved and are not covered by thissection.

If the ship is designed to operate on more than one fuel, (HFO and MGO or Natural Gas, forinstance), an endurance run may be required for each type of fuel to demonstrate capabilities and todemonstrate the ability to switch from one fuel to another.

2.3.2 Measurements and Instrumentation


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2.3.3 Trial Report

See tables in Section 6.0, Trial Data and Report.2.4 PROPULSION PLANT ASTERN TRIAL

2.4.1 Purpose and procedure

The primary purpose of the Astern Endurance Trial is to demonstrate satisfactory astern operation ofthe propulsion plant at specified operating conditions as contractually required or agreed. Thisshould include specific shaft power or revolutions per minute for a prescribed period of time. Anancillary benefit is proving the adequacy of piping supports, and equipment under severe vibratoryconditions.Difficulty in obtaining uniform propeller loading because of submergence variations due to ship

pitch, wave impingement or the uncontrollable circular track generally followed when a single-screwship is under sternway, often prevents steady propulsion plant operation. It is therefore advisable toestablish limits to astern RPM and prime mover parameters. As a result, the average indicated shaft

power for the astern run may be more or less than the target value.

Some ship specifications will limit sternway to that speed where by maximum rudder movement fromhard over will not result in rudder torque exceeding the maximum specified. In such cases themaximum astern speed should be established during the astern run by incrementally advancing

propeller speed until steering engine pressures indicate the maximum rudder torque specified.

Except as required for astern steering trials, the rudder should be held amidships during astern trials.

2.4.2 Measurement and Instrumentation

Instrumentation and the data system should be the same as that for Ahead Endurance Trials.

2.4.3 Trial ReportSee tables in Section 6.0, Trial Data and Report.

2.5 SPECIAL CONSIDERATIONS FOR DIESEL AND OTTO


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Special agreements should be made prior to trials for observing the performance of the auxiliarycomponents mentioned above.

2.5.2 Revolutions

Same as paragraph 2.2.5(c) except for installations having a reduction gear and/or a slip type coupling between the engine and the shaft. Then, both engine revolutions and shaft revolutions should beobtained.

2.5.3 Fuel Measurements

Same as paragraph 2.2.5(d) except as follows:

a) The fuel consumption of the main and auxiliary engines and any other fuel consumingequipment in operation should be measured separately.

b) Systems that return fuel to the upstream side of the supply meter should have the returnmeasured separately.

2.5.4 Fuel Rate Data RequiredSame as paragraph 2.2.5(e) except as follows:

Include return fuel oil meter readings with other meter data. In addition, fuel rate corrections for

variations of the following data from design conditions should be provided by the enginemanufacturer:

a) Inlet air temperature. b) Inlet air pressure.c) Inlet air moisture content.d) Engine RPM.e) Exhaust pressure.f) Fuel oil heating value.

The purpose of these corrections is to properly evaluate diesel engine performance. Suitable testdevices should be provided on trials to accurately measure these variables.

2 5 5 Power


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2.5.6 Fuel Switching

When two or more types of fuel are specified for normal operation, such as inside and outside of anEmission Control Area (ECA), the switching from one fuel type to the other and then back again, areto be demonstrated at the highest power level possible to demonstrate the limits at which fuelswitching can be carried out.

2.5.7 Daily Fuel Consumption and Ship’s Overall Fuel Rate

If desired, a daily fuel consumption rate could be provided based on tonnes/day at a specified power,electrical load, etc.

An overall fuel rate can possibly be developed to have meaning if tied carefully to specifiedoperational conditions. Fuel consumption of various components such as auxiliary engines or boilerswould need to be considered separately during the trials and then corrected to standard conditions.Use of different fuels would have to be analyzed and all values adjusted for fuel density and heatingvalue. An overall ships fuel rate could then be computed by summing the components and dividing

by some base reference number such as the propulsion shaft power.

2.5.8 Trial Data and Report

See tables in Section 6.0, Trial Data and Report.

2.6 SPECIAL CONSIDERATIONS FOR GAS TURBINEPROPULSION PLANT TRIALS

This section covers sea trial related items which are peculiar to gas turbine propulsion plants. Thisguide is written around the basic gas turbine propulsion unit consisting of a gas generating turbo-compressor and independent free power turbine. It should not preclude trial modifications, however,which future gas turbine development may dictate.

2.6.1 Auxiliary ComponentsThe following are examples of auxiliary components which may be part of the gas turbine plant:

a) Precoolers, intercoolers, and after coolers.


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e) Exhaust pressure.

These corrections are required to properly evaluate gas turbine performance. Suitable test devicesshould be provided on trials to provide the necessary data. Barometric pressure and relative humidityof the outside air should be recorded to permit evaluation of air inlet and exhaust duct systems. Theshipbuilder, however, is responsible for designing the air inlet and exhaust systems to meet designturbine inlet and exhaust conditions, and no correction to the ship's overall fuel rate should be

permitted for excessive pressure loss in these systems.

2.6.3 Power

When torsionmeters are not fitted, brake power for gas turbine engines may be estimated from theengine RPM, internal gas pressures and temperatures and/or fuel oil flow with sufficient accuracy forendurance trial purposes. Sample reference curves and correction factors will be very useful todevelop estimates.

When torsionmeters are required to be fitted, a correlation should be established during trials betweenthe power determined from the torsionmeter and the engine brake power as ascertained by the engine

pressure, RPM, and temperature data.

2.6.4 Trial Data and Report

See tables in Section 6.0, Trial Data and Report.

2.7 SPECIAL CONSIDERATIONS FOR ELECTRIC DRIVEPROPULSION PLANT TRIALS

Electric drive propulsion as covered in this section consists of electrical power generating equipmentand propulsion motor(s). Prime movers associated with the electric propulsion generators such as gasturbine, and diesel engines are covered in paragraphs above and are not repeated in this section.

2.7.1 Auxiliary ComponentsThe following are examples of auxiliary components which may be part of the electric drive

propulsion plant:


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2.8 CENTRALIZED PROPULSION CONTROL SYSTEM TEST

2.8.1 PurposeThe purpose of the test is to demonstrate the ability of the system to control the propulsion plant in alldesign modes and to demonstrate satisfactory propulsion plant response during transient operation atspecified rates and initial and final conditions.

2.8.2 ProcedurePrior to sea trials the control system and its subsystems, sensing elements, valve and equipmentoperators, safety devices, alarms, and indicators should have been tested for proper installation and

operation and should have been adjusted and timed to the values predicted to provide smooth andcorrect control of the ship at sea. Crewmen responsible for operations should be fully trained in thecapabilities and operation of the control system prior to sea trials. Satisfactory integrated operation ofthe total control system should also have been demonstrated to the extent practicable.

At the beginning of sea trials it is advisable to test the control system at reduced powers and make theindicated adjustments prior to demonstration of the full requirements. All required operations of thecontrols should be demonstrated under free route, maneuvering and emergency conditions inaccordance with the sea trial agenda agreed to in advance.

In addition to proper control in each mode, satisfactory transition between modes of control should bedemonstrated. When the bridge control is demonstrated, there should be no assistance from theengine room watch. When centralized engine room control is demonstrated there should be noassistance from local equipment watchstanders unless such manual participation .is incorporated in thedesign.

Safety features should be demonstrated at sea, if possible, without disrupting the adjustment of thecontrol system or setting up conditions beyond the operating range of the propulsion system.

2.8.3 Trial ReportSee Table 4 for recording data and reporting results.


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Table 4 Centralized Control System Tests

Ship Name Trial Date Start TimeSea State Ship's Heading Air Temperature oF/ oC

Centralized Control Maneuvers Position OrderedShaft RPM Response

Time (sec)Stop to Maximum Ahead (Stopping at eachmaneuvering speed position)

Maximum Ahead to Stop (Stopping at eachmaneuvering speed position)

Stop to Maximum Astern (Stopping at eachmaneuvering speed position)

Maximum Astern to Stop (Stopping at eachmaneuvering speed position)


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3.0 MANEUVERING AND SPECIAL TESTS

3.1 SELECTION OF TESTS

This section contains procedures for conducting maneuvering and other special trials and tests. Ship'sspecifications should include the owner's selection from the following tests:

Ahead Steering (Section 3.4) Astern Steering (Section 3.5)

Auxiliary Means of Steering (Section 3.6) Turning Circles (Section 3.7) "Z" Maneuver (Section 3.8) Initial Turning (Section 3.9) Pullout (Section 3.10) Direct Spiral (Section 3.11) Reverse Spiral (Section 3.12) Thruster (Section 3.13)

Quick Reversal from Ahead to Astern (Section 3.14) Quick Reversal from Astern to Ahead (Section 3.15) Low Speed Controllability Maneuvers (Section 3.16) Slow Steaming Ability (Section 3.17) Emergency Propulsion Systems (Section 3.18) Navigation Equipment (Section 3.19)

In selecting tests, consideration should be given to the requirements contained in IMO.137(76)"Standards for Ship Manoeuvrability" and to the purpose of the test. Some tests are essential to

provide the information necessary to comply with IMO Resolution A601(15) "Provision and Displayof Manoeuvring Information on Board Ships", which lists information to be available on the bridge inthe Pilot Card, Wheelhouse Poster, and Manoeuvring Booklet. It is also essential to verify that thevessel has satisfactory basic course keeping and turning qualities. The data can also be useful in


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is the speed at which the ship may be expected to navigate in areas where maneuvers are normallyrequired, and are not restricted by insufficient water depth or channel boundaries.

In the case of slow, full form ships this speed may be close to design sea speed. For fast, fine-formships on the other hand, it may be a much lower proportion of design speed. The following formula issuggested as a guide to selecting test speed:

VT = C B x V D

where: V T = test speed

VD = design speed

CB = block coefficient at the design draughtThis formula provides test speed values for bulk carriers and dry cargo/container ship types which areoften used in general practice. Unless otherwise indicated tests should be commenced at the testspeed.

3.2 PREPARATION

Proper preparation is essential to obtain meaningful data and avoid aborting mandatory tests.Detailed instruction for performing each test, including maneuvering diagrams and data sheets where

pertinent, should be prepared in advance. Test conductors and data takers should be instructed intheir duties, shown their station, checked out on instruments, and have their understanding of the testverified.

3.3 REPORTS

Reports should present the data in tabular or diagrammatic format. Sample diagrams and data sheetsare shown in this Section and in Section 6. Reports should include, where pertinent, discussion of thesignificance of findings and an explanation of data anomalies. Reported information should be ofsufficient detail to provide the data required to prepare the Pilot Card, Wheelhouse Poster, andManeuvering Booklet described in IMO Resolution A.601(15) and the first order steering qualityindices K and T.


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d) Maximum oil pressure on ram.e) Servo pressure, replenishing pressure and pump stroke at maximum demand, if available

from ship's instruments and indicators.f) Power unit in use and idle volts, amps and RPM.g) Steering gear motor minimum and maximum volts, amperes, and RPM for each rudder

movement.h) Propeller shaft RPM at start and finish of test on each unit.i) Depth of water, sea condition, and wind direction.

j) Steering station in controlk) Trial drafts, fore and aft.

The above test is appropriate for dual power unit electro-hydraulic systems. If a different system isinstalled, suitable adjustments to the requirements should be made. The ahead and astern steeringtests demonstrate steering machinery capability.


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Table 5 Steering Tests Ship Name Ahead Steering Astern

SteeringAuxiliary

Steering (Ifdemonstrated)

Unit (P or S) Unit (P or S) Unit (P or S)

Trial DateTime of TestBase CourseDepth of Water

Sea ConditionWind DirectionWind VelocityTrial Draft (Fwd)Trial Draft (Aft)Propeller RPM (beginning)Propeller RPM (end)Steering Station in ControlRudder Movement Time (Sec.)b

O-R O-L O-R O-L O-R a

R-L L-R R-L L-R R-LL-R R-L L-R R-L L-RR-O L-O R-O L-O R-O

Maximum Rudder Angles O-R O-L O-R O-L O-R aR-L L-R R-L L-R R-LL-R R-L L-R R-L L-R

Max. Steady Motor Amps O-R O-L O-R O-L O-RR-L L-R R-L L-R R-LL-R R-L L-R R-L L-R


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3.5 ASTERN STEERING

With the ship in the trial ballast condition and moving astern at maximum astern shaft speed, usingeither one of the main power units, move the rudder at maximum rate as follows:

1. Midships to Hardover Right - Hold ten seconds.2. Hardover Right to Hardover Left - Hold ten seconds.3. Hardover Left to Hardover Right - Hold ten seconds.4. Hardover Right to Midships - Maneuver complete.

Record data as described in paragraph 3.4 above.

3.6 AUXILIARY MEANS OF STEERINGWhere auxiliary power steering means is specified to control the rudder at reduced ship's speed, rate,and range of rudder movement, such operation should be demonstrated at sea. In addition to shaftRPM and time of rudder movements, the time necessary to secure normal mode and activate theauxiliary unit should be recorded. When the standby unit of a dual hydraulic steering gear is thespecified auxiliary means of steering, it is tested under paragraph 3.4, and the test need not berepeated.

3.7 TURNING CIRCLESTurning circles should be performed to both right and left with 35 degrees rudder angle or themaximum design rudder angle permissible at the test speed.

The essential information to be obtained from this maneuver consists of tactical diameter, advance,and transfer. Also of interest are the final ship speed and yaw rate in the "steady state" of the turningcircle. A turning circle of at least 540 degrees should be completed to determine the main parametersof the maneuver and allow correction for any drift caused by a steady current or wind. Appendix B

presents an acceptable method for correcting measurements for ship drift during the test.With the ship in the trial condition and proceeding ahead at the maximum trial shaft RPM, with eithersteering power unit, move the rudder at maximum rate and perform the following maneuvers:


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e) Ship's position at suitable intervals from GNSS equipment. If GNSS equipment is notinstalled, ship's track should be obtained by radar, shore station tracking, or visual

observation of the wake. Observation intervals should coincide with heading data intervals.f) Shaft RPM at beginning and end of each circle.g) Depth of water and sea condition.h) Wind direction and velocity.i) Trial draft fore and aft.

Turning circle tests may be specified at depths, drafts, speeds, and rudder angles other than thosegiven if ship's maneuvering characteristics require further exploration.

At the completion of each of the turning circle tests a pullout test may be performed to provideinformation on the ship's dynamic stability. For further information see paragraph 3.10.

Turning circles should be plotted and tactical dimensions reported as illustrated in Figure 1 andFigure 2. Figure 1 shows the historic test resulting in measures of advance, transfer, and tacticaldiameter. Using today’s high precision position tracking systems, maximum ship advance andtransfer measurements are included (see Figure 2) . The entire swept path can also be depicted in the

plot

.


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Table 6 Turning Circle Test Data

Time (sec) Heading from BaseCourse

NOTE: Representation of the ship should be aline scaled in length, oriented to and locatedon the circle such that the stern clearancetrack can be determined.Ship NameTest DataTime Test BeganBase Course

Rudder AngleShaft RPM(Beginning)Shaft RPM (End)Depth of WaterSea ConditionWind VelocityTrial Draft (fwd)

Trial Draft (aft)Maximum DriftCorrection

Di Di i


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3.8 "Z" MANEUVER*

The "Z" Maneuver is shown in Figure 3 and may be identified as the Zig-Zag Maneuver or the KempfManeuver.

With the ship in trial condition and proceeding ahead into the wind at the maximum trial shaft RPM,with either steering power unit, move the rudder at maximum rate and perform the followingmaneuvers:

1. Move the rudder from center to 10 degrees right - hold until ship's heading is 10 degrees tothe right of the original course.

2. Move the rudder from 10 degrees right to 10 degrees left hold until ship's heading is 10degrees to the left of the original course.

3. Move the rudder from 10 degrees left to 10 degrees right hold until the ship's heading is 10degrees to the right of the original course.

4. Move the rudder from 10 degrees right to center hold until original heading is restored.Steady on original course.

In some cases it may be desirable to modify the test so as to include a fifth rudder movement in orderto collect additional data for other analysis. A pullout test may also be performed upon completion ofthe "Z” Maneuver.

The standard type "Z" Maneuvers are the 10°/10° (which is a 10° rudder change and a 10° change ofheading at next rudder execute, etc.) and the 20°/20° tests. Both the 10-10 and 20-20 maneuvers arespecified in the IMO Standards, the latter primarily because of the large body of trials data availablefor this maneuver. The trials data base for evaluating results of the 20-10 maneuver is not large.Thus conducting this trial maneuver may not be that useful. There is a growing body of data,however, for 5-5 and 5- 1 “Z” maneuvers because these maneuvers are more quickly accomplishedthan 10-10 or 20-20 maneuvers and they can clearly identify unstable ships and potentially eliminateor reduce the cost of time-consuming spiral maneuvers.

At least one standard type "Z" Maneuver should be performed at the test speed. The 10 °/10 ° test is preferred as it provides better discrimination between ship characteristics. The 20°/20° test shouldalso be included to provide a comparison with data available from earlier tests The 20°/10° tests are


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Figure 3 "Z" Maneuver Test (Courtesy of ABS)


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Table 7 "Z" Maneuver Test Data

Ship NameTest Date

Time Test Began

Base Course

Shaft RPM (Beginning)

Shaft RPM (End)

Depth of Water

Sea Condition

Wind Direction

Wind Velocity

Trial Draft (fwd)

Trial Draft (aft)

Elapsed Time (sec) Ship Heading Departure from Course


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3.9 INITIAL TURNING TESTS

The initial turning tests provide information on the transient heading condition between steady stateapproach and change of heading after application of the rudder as shown in Figure 4 and Figure 5. These tests should be performed with rudder angles of 10 degrees and 20 degrees. The time historyof heading and yaw rate should be plotted. These tests may be performed in conjunction with turningcircle tests and partially with "Z" Maneuvers, which are described in Sections 3.7 and 3.8,respectively.

With the ship in the specified trial conditions and proceeding ahead at the designated speed and on a

steady course, conduct the maneuver as follows for two separate tests, one at a rudder angle of 10degrees and one at a rudder angle of 20 degrees.

Lay the rudder over to the specified setting and hold until the ship has moved at least 2.5 ship lengthsor until the turning becomes steady. IMO standards require initial turning performance only at 10degrees rudder angle (10 degree change of heading angle when the ship has moved 2.5 ship lengths).

The following data should be recorded on Table 8:

(a) Before starting the test:

1) Time of test and base course.2) Ship speed and corresponding RPM.3) Wind velocity and direction.4) Depth of water and sea condition.5) Trial draft.

(b) During the test:

Rudder Angle. Both heading and rate of change of headings should be plotted for each rudder position.


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Figure 4 Initial Turning Test, Change of Heading Plot


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Table 8 Initial Turning Test Data

Rudder Angle Ship NameElapsed Time

(sec)Heading

Test Date

Time Test Began

Base Course

Rudder Angle

Shaft RPM (Beginning)

Shaft RPM (End)

Depth of Water

Sea Condition

Wind Direction

Wind Velocity

Trial Draft (fwd)

Trial Draft (aft)

3.10 PULLOUT TESTS

The pullout test gives a simple indication of a ship's dynamic stability on a straight course. The shipis first made to turn with a certain rate of turn in either direction, upon which the rudder is returned toamidship. If the ship is stable, then the rate of turn will decay to zero for turns to both left and right.If the ship is unstable, then the rate of turn will reduce to some residual rate of turn. The pullout testsmust be performed to both left and right to show possible asymmetry.


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Table 9 Pullout Test Data

Time(sec) Headingfrom BaseCourse

Speed(knots) RPM

Ship NameTest DateTime Test BeganBase Course

Rudder AngleShaft RPM (Beginning)Shaft RPM (End)Depth of WaterSea ConditionWind DirectionWind Velocity

Trial Draft (fwd)Trial Draft (aft)


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3.11 THE DIRECT SPIRAL TEST

The direct spiral test is an orderly sequence of turning tests to obtain a steady turning rate versusrudder angle relationship.

This test can be a time consuming test to perform, especially for large and slow ships. The test isvery sensitive to weather conditions and a significant amount of time and care is needed for the shipto obtain a steady rate of change of heading after each rudder angle change.

The IMO requires a determination of the instability loop width for all unstable ships. As spiral testsare expensive to conduct, these tests probably do not need to be conducted if positive stability isclearly demonstrated from results of pullout tests or from a 5-5 or 5- 1 “Z” maneuver. Where anyquestion about stability exists a spiral test will be required.

Ship's speeds most unfavorable to directional stability at trial draft should be estimated and specifiedfor the test. Since this test may be adversely affected by the elements, it should be conducted only inrelatively calm seas, i.e., sea state 3 or less, and winds of less than 10 knots.

With the ship in the specified trial condition and proceeding ahead at the designated speed and on asteady course, using either steering power unit, conduct the maneuver as follows:

1. Turn the rudder 20 degrees to right and hold until the turning rate becomes steady.2. Move the rudder to the following settings and hold at each until the turning rate in

degrees per second becomes steady: 20 oR, 15 oR, 10 oR, 5 oR, 3 oR, 1 oR, 0 o, 1oL, 3 oL,5oL, 10 oL, 15 oL, 20 oL, 15 oL, 10 oL, 5 oL, 3 oL, 1 oL,0 o, 1oR, 3 oR, 5 oR, 10 oR, 15 oR, 20 oR

A steady turning rate is the difference between successive ship headings and should be noted as thetest progresses. When these differences are reasonably constant for at least six consecutive readings,data is recorded and the rudder is ordered to the next setting.

The following data should be recorded as indicated in Table 10:


1) Ti f t t d b


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Table 10 Direct Spiral Test

Ship NameTest DateTime Test BeganBase CourseRudder AngleShaft RPM (Beginning)Shaft RPM (End)Depth of WaterSea ConditionWind DirectionWind VelocityTrial Draft (fwd)Trial Draft (aft)

Data for Step No. Rudder AngleTime (sec) Ship Heading Change in Ship Heading

(Consistent for 6 consecutive readings)

Notes:A total of 6 readings of constant rate of heading change is needed to calculate average

i D /S d Thi l l i i d f h


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12 15 L13 20 L14 15 L15 10 L16 5 L17 3 L18 1 L19 020 1 R21 3 R22 5 R23 10 R24 15 R25 20 R

Step Yaw Rate(Deg/Sec)

RudderAngle

1 1.0 R2 0.8 R3 0.6 R4 0.4 R

5 0.2 R6 0.1 R7 0


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Figure 7 Direct Spiral Test

3.12 THE REVERSE SPIRAL TEST

The reverse spiral test may provide a more rapid procedure than the direct spiral test in defining theinstability loop as well as the unstable branch of the yaw rate versus rudder angle relationship.

I h i l h hi i d f d h dd l


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rate of turn have been obtained. Steady rate of turn should usually be obtained fairly rapidly sincerate-steering is easier to perform than normal compass steering.

The test should be performed at the following steady rates of turn in degrees per second: 1.0R, 0.8R,0.6R, 0.4R, 0.2R, 0.1R, 0, 0.1L, 0.2L, 0.4L, 0.6L, 0.8L, and 1.0L.

The following data should be recorded:


1. Time of test and base course2. Ship speed and corresponding RPM3. Wind velocity and direction4. Depth of water and sea condition5. Trial drafts

(b) The average rudder angle associated with each associated steady state turn rate measurement point.

This procedure should be repeated for a range of yaw rates until a complete yaw rate versus rudderangle relationship is established, e.g., between 20 degrees left to 20 degrees right rudders.

The results of the spiral tests should be presented in accordance with the diagrams provided in Figure8. The pronounced "S" shape on Figure 8 illustrates a ship with instability, and this instability

provides a hysteresis loop like that illustrated in Figure 7 (b), Unstable Ship, for the rate of change ofheading.


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Table 11 Reverse Spiral Test Data

Ship NameTest DateTime Test BeganBase CourseRudder AngleShaft RPM (Beginning)Shaft RPM (End)Depth of WaterSea ConditionWind DirectionWind VelocityTrial Draft (fwd)Trial Draft (aft)

Data for Step No. Rudder AngleTime (sec) Ship Heading Change in Ship Heading

(Consistent for 6 consecutive readings)

Notes:A total of 6 readings of constant rate of heading change is needed to calculate average rate inD /S d Thi l l ti i d f h t


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3.13 THRUSTER TESTS

3.13.1 Bow Thruster TestsIn addition to the performance test data of flow thrusters obtained during dock trials, tests of bowthrusters at sea demonstrate thruster effectiveness in turning the ship.

With the ship in trial condition, conduct the maneuvers below. It should be noted that reduced thrustmay result unless submergence of the thruster axis of at least 0.8 times the thruster diameter is

provided.

Bow thruster tests for dry cargo ships in the trial ballast condition are severely influenced by sea and

wind a

sea trial procedure

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