Sea Trial Procedure

Technical and Research Program

The Society of Naval Architects and Marine Engineers

99 Canal Center Plaza, Ste 310, Alexandria, VA 22314

www.sname.org

T

&

R

Bulletin

3-47

Guide for Sea Trials

iii

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

Published by

The Society of Naval Architects and Marine Engineers

99 Canal Center Plaza, Alexandria, Virginia 22314

Copyright 2015 by the Society of Naval Architects and Marine Engineers with rights reserved.

i

This Bulletin was prepared under direction from the Ships Machinery Committee

for

THE SOCIETY OF NAVAL ARCHITECTS AND MARINE ENGINEERS

TECHNICAL AND RESEARCH PROGRAM

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

Groups and Volunteers

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

Mr. Roderick Barr

Mr. Robert Behr

Mr. Jeffrey Bohn

Mr. Karl Briers

Mr. Christopher Cable

Mr. Bruce Cowper

Mr. Brice Fuchs

Mr. Soren Hanson

Dr, Wei-Yuan Hwang

Captain Tom Knierim

Mr. Darrell Milburn

Mr. Jan Otto de Kat

Mr. Frans Quadvlieg

Mr. J. Ryan Roberts

Mr. Eugene Van Rynbach

Mr. Mark Shanks

Mr. Gene Shuck

Mr. Malcolm Whitford

Reviewed and Approved by:

SHIPS MACHINERY COMMITTEE

Mr. Richard Delpizzo, Committee Chair

Mr. Robert J. Bazzini Mr. Robert S. Behr Mr. John W. Boylston Mr. William G. Bullock Mr. Hannon Marshal Burford Mr. Allen Chin Mr. Joseph H. Comer Mr. W. Mark Cummings Mr. John J. Dumbleton Mr. Jose Femenia Mr. Earl W. Fenstermacher Mr. Robert M. Freeman Mr. Joseph D. Hamilton Mr. Richard W. Harkins Mr. John F. Hennings Mr. Richard D. Hepburn Mr. Bahadir Inozu Mr. Charles A. Narwicz Mr. Mark F. Nittel Mr. Michael G. Parsons Mr. Kevin Prince Mr. Michael J. Roa Mr. David R. Rodger Mr. Alan L. Rowen Mr. Peter George Schaedel Mr. John Thomas Schroppe Mr. William J. Sembler Mr. Tony Teo

Mr. Richard P. Thorsen Mr. Andrew Szypula Mr. Ivan Zgaljic

Abstract

This guide covers progressive speed, maneuvering, and endurance sea trials of self-propelled surface ships 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 are made to applicable international standards. This Bulletin does not cover dock trials, tests, or demonstrations 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 the owner, designer and builder to rate the vessel’s maneuvering performance relative to statistical data of vessel maneuvering characteristics. The Guide summarizes the procedures to be used in assessing a vessel’s maneuvering performance.

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

Preface

This document evolved from the worldwide use of The Society of Naval Architects and Marine Engineers' (SNAME) Code for Sea Trials - 1973 (Technical and Research Code C-2) dealing with sea trials. The Ships' Machinery Committee of the Society's Technical and Research Program assigned the initial expansion and update of the document to Panel M-19 (Ship Trials) with the assistance of Panel 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 and frequency 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, updates were long overdue in recognizing technological advances in sea trial instrumentation, the change from steam propulsion to diesel and other modern propulsion systems, recognition of other technological advances and updates of the International Maritime Organization (IMO) and other standards 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 and issued. 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 trials and tests to enable an owner or acceptance authority to choose those suitable for the type of ship and operation involved. Positive contractual invocation of specific individual trials is recommended rather 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 recommended does not imply a negative recommendation by the Society, but merely that the primary objective of such a test or trial is to provide design data to meet some other important objective, rather than to prove the ship under trial. Similarly, the omission of requirements is not intended to negate the value of the efforts which are directed to verifying design standards, scale factors, and margins rather than the acceptability of the ship. Some examples of omitted requirements are the extensive processing of trial data and the correcting of trial data to a design baseline when the data obtained clearly indicate that the ship is satisfactory. Such tests, trials, data processing, and data correcting should be separately and specifically invoked when desired.

Trial recommendations are based on the assumption that all operability testing and machinery checkouts have been previously conducted at the dock insofar as conditions at the shipbuilder's plant permit. Methods of analysis of results from trials are not included herein, in general, but may be found in the technical literature and in other guides of the Society.

Section 1 of the guide includes general remarks applicable to any sea trial and provides a basic recommendation for trials to be conducted. Sections 2, 3, and 4 provide instructions for sea tests and trials. Section 5 provides a brief description of instruments used for trials and a bibliography of publications which can be consulted for detail. It also includes instructions for instrumentation peculiar to trials, in particular, torsionmeters. Section 6 establishes a format and provides illustrative

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forms for the presentation of sea trial reports. Appendices include definitions of terms peculiar to sea trials 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 that successful performance of the recommended trials will ensure that a ship will comply with the requirements 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 of SNAME 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 or members.

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 that allowed 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 a number of figures from their publications available for the update. Student Samantha Adornati from Stevens Institutes under the direction of Professor Raju Datla is recognized for drafting and/or revising figures in the guide.

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 or members.

iii Page

TABLE OF CONTENTS

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

1.5.6 Demonstration of Controllability... 2

1.5.7 Establishment of Operating Performance Baseline ... 2

1.5.8 Provision of Forensic Data ... 2

1.5.9 Provision of Design Data ... 2

1.5.10 Classification and Safety Requirements ... 3

1.6 SHIP AND ENVIRONMENTAL CONDITIONS ... 3

1.6.1 Sea Trial Loading Conditions ... 3

1.6.2 Water Depth... 3

1.6.3 Wind, Waves, and Currents ... 4

1.7 LIST OF TRIALS AND SELECTION ... 4

1.8 RECOGNITION OF UNCERTAINTY ... 6

1.9 PLANNING ... 6

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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

2.4 PROPULSION PLANT ASTERN TRIAL ... 16

2.4.1 Purpose and procedure ... 16

2.4.2 Measurement and Instrumentation ... 16

2.4.3 Trial Report ... 16

2.5 SPECIAL CONSIDERATIONS FOR DIESEL AND OTTO CYCLE ENGINE PROPULSION PLANT TRIA LS ... 16

2.5.1 Auxiliary Components ... 16

2.5.2 Revolutions ... 17

2.5.3 Fuel Measurements ... 17

2.5.4 Fuel Rate Data Required ... 17

2.5.5 Power ... 17

2.5.6 Fuel Switching ... 18

2.5.7 Daily Fuel Consumption and Ship’s Overall Fuel Rate ... 18

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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

3.9 INITIAL TURNING TESTS ... 35

3.10 PULLOUT TESTS ... 37

3.11 THE DIRECT SPIRAL TEST ... 40

3.12 THE REVERSE SPIRAL TEST ... 43

3.13 THRUSTER TESTS... 46

3.13.1 Bow Thruster Tests ... 46

3.13.2 Other Thrust Devices ... 48

3.13.3 Special Thruster Tests ... 48

3.14 QUICK REVERSAL FROM AHEAD TO ASTERN (“CRASH ASTERN” STOPPING TESTS) ... 48

3.15 QUICK REVERSAL FROM ASTERN TO AHEAD ... 51

3.16 LOW SPEED CONTROLLABILITY MANEUVERS ... 51

3.17 SLOW STEAMING ABILITY ... 53

vi 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

5.1 GENERAL ... 60

5.1.1 Introduction ... 60

5.2 TEMPERATURE MEASUREMENTS ... 60

5.2.1 Types of Instruments ... 60

5.2.2 Thermowells and Temporary Installations ... 60

5.2.3 Adapters for Sensing Elements... 61

5.2.4 Instrument compatibility ... 61

5.2.5 Calibration and Sea Trials ... 61

5.2.6 Special Thermocouples ... 61

5.3 PRESSURE MEASUREMENTS ... 61

5.3.1 Types of Instruments ... 61

5.3.2 Proper Connections and Protection ... 61

5.3.3 Zero Adjust for Elevation ... 62

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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 5.7.3 Types of Instruments ... 66

5.8 SHAFT SPEED MEASUREMENTS ... 66

5.8.1 Propeller Revolution Counters ... 66

5.8.2 Portable Tachometers and Speed Indicators ... 67

5.8.3 Additional 'Information ... 67

5.9 FLUE AND EXHAUST-GAS ANALYSES ... 67

5.9.1 Orsat Analyzer ... 67

5.9.2 Manual and Automatic Types of Flue Gas Analyzers ... 69

5.9.3 Additional Information ... 69 5.10 VISCOSITY MEASUREMENTS ... 69 5.11 ELECTRICAL MEASUREMENTS ... 69 5.11.1 Measuring Devices ... 69 5.11.2 Calibration ... 69 5.11.3 Additional Information ... 69

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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

6.5 STANDARDIZATION TRIALS ... 74

6.6 FUEL ECONOMY AND ENDURANCE TESTS ... 74

6.7 PROPULSION PLANT TRIALS ... 77

6.8 TRIAL REPORT ... 78 6.8.1 Introduction ... 78 6.8.2 Ship's Characteristics ... 78 6.8.3 Trial Data ... 79 6.8.4 Other Data ... 79 6.8.5 Appendices - As Elected ... 79 REFERENCES ... 87 APPENDIX A DEFINITIONS... 89

A.1 GENERAL TERMS ... 89

A.2 PROPULSION PLANT TRIALS ... 90

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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 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

Figure 11 Sample Plot Illustrating Correction of Turning Circle for Drift ... 95

LIST OF TABLES

Table 2 Recommendations for Internal Combustion Propulsion Plant Trials ... 11

Table 3 Recommendations for Gas Turbine Propulsion Plant Trials ... 12

Table 4 Centralized Control System Tests ... 21

Table 5 Steering Tests ... 26

Table 6 Turning Circle Test Data ... 31

Table 7 "Z" Maneuver Test Data ... 34

Table 8 Initial Turning Test Data ... 37

Table 9 Pullout Test Data ... 39

Table 10 Direct Spiral Test... 41

Table 11 Reverse Spiral Test Data ... 45

Table 12 Thruster Test Data ... 47

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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

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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 3-47 Guide for Sea Trials 1989.

1.2 ORIGIN

This Guide was developed by updating the 1989 Guide for Sea Trials-1989 that was produced by SNAME Panel M-19 (Ship Trials) with assistance from Panel H-10 (Ship Controllability) and approved by the Ships’ Machinery Committee of SNAME. This update effort was supported by funding from the National Shipbuilding Research Program. Those contributing to the update include a variety of volunteers from organizations including shipbuilders, ship owners, ship designers, operators, Classification Society, Government organizations and others. Publications of other SNAME Technical Panels, Classification Societies, and international standards organizations were consulted to check compatibility and various sources in the technical literature were researched for advances 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 IMO Resolution 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 definitive information on ship trials to form a basis for contractual agreement.

1.4 SCOPE

The Guide covers sea trials of self-propelled surface ships, commercial or naval, displacing 300 tonnes or more, powered by hydrocarbon fuels such as petroleum, natural gas and bio fuels and driven by diesel or Otto cycle engines, gas turbine, or electric motors. It does not cover dock trials, tests or demonstrations that can be conducted dockside. For these type of tests refer to SNAME Technical and Research Bulletin 3-39, Guide for Shop and Installation Tests-1985.

Nothing in this Guide should be construed to delete or modify requirements of specified regulatory bodies.

1.5 TRIAL OBJECTIVES

A sea trial may have one or more of the following objectives depending on the position of the ship in its class, the innovative content of its design, and the needs or desires of its owners.

1.5.1 Demonstration of Operability

The ship propulsion and control systems can be shown to operate in their design modes only at sea, and the shipbuilder and customer both benefit from a demonstration of proper operation that verifies the correctness of construction, manufacture, and installation.

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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 first ship of a class to verify the adequacy of the design of the propulsion plant and its supporting auxiliaries.

1.5.3 Demonstration of Endurance

Demonstration of ability to maintain maximum power and speed for sufficient time to develop equilibrium conditions and to operate at those conditions for the prescribed period without failure of system components is important for every ship. It is assumed that the ability to operate in this manner indefinitely, or for the design life, will thereby have been demonstrated, since any functional inadequacies 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 penalty involved or when required by the ship's specifications. Attainment of the best possible fuel consumption is important when there is a bonus involved. When neither are involved it is still required to determine fuel rate for the first of a class to verify design and for subsequent ships to verify 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 energy efficiency (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, checking turns, operating at acceptably slow speeds, and stopping in a satisfactory manner is important for safe operations 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 ships and to a lesser degree for individual ships so that ship operators will have a standard with which to compare current operating data enabling monitoring of plant performance and operational capabilities. Performance baseline data is also important for populating onboard performance monitoring systems used in optimizing vessel operations.

Ship pilots as well as operators also need to know the controllability characteristics of the vessel. Properly developed ship trial test data reported according to the comprehensive guidelines of IMO Resolutions A.751 and A.601 (15) (see for instance the ABS Guide for Vessel Maneuverability) provide such data in a standard format for operator use.

1.5.8 Provision of Forensic Data

It is increasingly important for ship operators to have available certifiable data on the ship's maneuvering capabilities in the event the ship is involved in legal action for collision damage. Data from other ship systems may be pertinent to litigation involving habitability, safety or pollution responsibilities.

1.5.9 Provision of Design Data

All trial data augments the bank of design data on which naval architects and marine engineers draw upon. This allows greater predictability during the design process permitting the required performance characteristics to be delivered with greater confidence. Special data to verify the success

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of innovative features or to advance the state of the shipbuilding art may be called for. In such cases it 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 data on ship maneuverability in its developing and refining of standards and has detailed specific maneuvers that are included herein.

1.5.10 Classification and Safety Requirements

Classification societies and safety authorities often require demonstration of equipment and systems which 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 performed at 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 73/78 MARPOL 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 provided with full draft capability via ballasting, trial drafts will not approximate maximum design draft, and demonstrations of capabilities that are draft dependent, such as ship's speed and maneuverability, are of limited value. In such cases it is advisable to specify model tests at anticipated trial drafts as well as maximum design draft, as without such tests, extrapolation of trial results depends on uncertain estimates. Trials should be conducted at drafts as close as practicable to the model test conditions. In the absence of model test data as a reference point, standardization results at other than the maximum design draft is not recommended.

1.6.2 Water Depth

The most demanding operational requirements for many ships are met in shallow water during coastal and port navigation. Unfortunately, the usual practice is to perform ship trials in deep water for standardization and comparative purposes. The adequacy of a ship's capabilities in shallow water, particularly maneuvering characteristics, must usually be inferred or predicted based on its success in deep water, and from comparison of its deep water characteristics relative to other vessels.

Ships interact with the bottom, with banks, and with other vessels in restricted waters with very significant effects on ship movement. Trials should therefore always be made in deep unconfined waters where possible.

To minimize the possibility of such effects on the underway performance trial results of the ship, water depth, other than for special trials to investigate shallow water capabilities, should always exceed five times the mean draft of the ship. During speed trials additional depth is needed based on speed and vessel midship section area:

H > 5.0 (Am) 1/2

H > 0.4 V2 where:

4 H = Water Depth (m)

Am = Midship Section Area (m 2

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

1.6.3 Wind, Waves, and Currents

The uncontrollable environmental conditions of wind, waves, and currents can significantly influence the results of all underway trials. These effects are also difficult to account for. Trials should thus be held in the calmest weather conditions available. Wind direction and speed should be noted at the start of each test, so that the effects can be studied and corrections applied. Currents, wave, and swell conditions 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 a significant wave height of up to 1.25 m, should be avoided for ships under 152.4 m (500 feet) in length.

Wind speeds of more than 10 m/second (19.4 knots or nmi/hr) should be avoided. Maneuvering spiral 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 the user 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 in excessive costs with little value. Users should study the Guide, and then when writing their ship’s specification 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 for convenience. If this Guide is invoked by contract, all of the recommended trials and tests are to be conducted except for those specifically deleted, and trials or tests marked "If Elected" are to be conducted only if specifically invoked.

While some tests are required by international regulations or regulatory body requirements and must be run, other tests in this guide should be run if needed for specific demonstration of capabilities. Listed below are the names and tests covered in this Guide. The recommendation associated with the name of each test is provided to assist in developing a trials program. Further guidance on the purposes of each test and when it may be useful can be found in the column titled Guide Paragraph. The tests and recommendations are shown on Table 1.

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Table 1 Recommended Trials

Name

Recommendation

Guide

Paragraph

Economy Trials First of a Class only 2.2

Endurance Trials All Ships 2.3

Astern Trial All Ships 2.4

Diesel 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) 3.12

Thruster First of a Class only 3.13

Quick Reversal from Ahead to Astern All Ships 3.14 Quick Reversal from Astern to Ahead All Ships 3.15 Low Speed Controllability If Elected 3.16

Slow Steaming Ability All Ships 3.17

Emergency Propulsion Systems If Elected 3.18

Navigation Equipment All Ships 3.19

Standardization Trials First of a Class only 1.5, 2, 4

(1) Derived from paragraphs 3.7 and 3.8 (2) Alternative to "Direct Spiral"

It should be noted that some of these tests can be run concurrently.

For twin screw ships, owners may want to consider running tests to examine the conditions of lost power to one shaft. Tests with one shaft in a locked or trailing mode can be run to examine effects on speed and maneuverability.

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

1.8 RECOGNITION OF UNCERTAINTY

Although ship designers, builders, and trial personnel may exercise greatest diligence in pursuing their art at the most advanced state, there is inherent in the measurement of ship performance an unavoidable uncertainty. No measurement is perfect and shipboard conditions preclude the use of the most precise techniques. Since the major ship performance parameters involve measurement of many fluctuating quantities, each with an element of uncertainty, the cumulative effect might be considerable. 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 degree of 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 results and 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 to ISO 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 data crews; 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 depth of instrumentation and the data to be reported. If this Guide is properly cited in the ship's specifications, requirements should be clear. If the Guide is not cited or there remains an area of doubt, the shipbuilder, owner, and regulatory bodies involved, should reach agreement as soon as possible after the award of a contract, using this Guide as a basis for understanding.

Presuming that agreement has been reached, the actions outlined below can be taken as applicable. References in this guide are made on occasion to other documents that provide additional useful information.

1.9.1 Design Accommodation

(a) If a torsionmeter is to be installed, care should be taken in its location on the shafting with adequate clearance provided (ISO 15016.2 addresses various issues). If required, special surface finish and dimensional constraints should be imposed. If the shaft is hollow, the supplier of the rough machined unit should be alerted to provide precise internal diameter measurements. Mounting of signal transfer equipment or brush rigging should also be considered (current practice includes the use of wireless links from shaft mounted strain gages).

7

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

(c) If special gages, thermometers or orifices are to be installed, sensing points should be selected 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 by the government, or procured or overhauled if furnished by the contractor; the torqueing gear should be made ready, the calibration accomplished and the instrument factors established. Unless permanent torque meters are installed, this measurement is done using 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 technical representatives 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 trial data calibrated, “red line” settings made and “water legs” measured. Sensor calibration should include addressing remote or indirect means the sensor relies on for accuracy. (h) Data forms (paper or digital) should be prepared and the graphical interface checked

against the ship as built, preferably by using them for Dock Trials to allow for proper data quality assurance.

(i) Trial operating crew and data crew should be trained unless previously trained or experienced.

(j) Calculation sheets or a data acquisition system (DAS) and computerized quality analysis (QA) sheets should be prepared, with dummy calculations and correction tables or plots provided.

(k) GNSS tracking system, if to be aboard, including antenna should be installed and checked.

(l) A sample of the fuel expected to be burned should be sent to a laboratory for gravity and heat content determination when fuel rates are to be calculated.

(m) Trial agenda, procedures, and schedules should be prepared and furnished to the owners for comment.

(n) Trial control and the data acquisition system should be planned and facilities installed, including appropriate communications and reference material.

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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 use a check list. Such a list should include all machinery, equipment, and trials to be tested and pretests or 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 the trial or runs is to be presented for acceptance, the owners, acceptance authorities, and involved regulatory bodies should be notified in advance. If builder’s trials are not specified, they are to be at the 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 Section

This section contains recommendations for conducting internal combustion engine, gas turbine, and integrated 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 under trial conditions. The instructions herein are intended to cover testing of the propulsion plant as an integrated system underway and do not cover ship or shop tests of individual equipment items, dock trials, or dockside tests required by specifications or regulatory bodies, unless prescribed herein as incidental 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 minute when trial draft or other conditions make full power unattainable within shaft speed limitations.

2.1.3 Pre-Trial Agreements

Prior to the trials, there should be a clear understanding with respect to the following:  The specific objectives of the trials.

 The trial agenda and tentative schedule.

 Conditions and methods of operation during the trial.

 Corrections, if any, to be applied for deviations from specified conditions or specific standards.

 Measurement methods, temporary test equipment and instrumentation.  Trial drafts.

 Duration of each trial run. Frequency of readings and measurements including digital sampling rates.

2.1.4 Trial Preparations

Preparation for propulsion plant trials as, defined in this section should include the following:

 Calibration of shafting to determine modulus of rigidity, or if the shaft is not to be calibrated, then an agreement on the modulus to be used.

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 Calibration of trial fuel meters. Where ship’s meters are used as trial or trial back-up instrumentation, they should also be calibrated.

 Calibration of special gages and meters. Records of calibrations should be available prior to trials 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 otherwise specified or agreed.

Unless otherwise agreed, any run, which has been interrupted by machinery casualties necessitating slowing down or stopping, should be entirely rerun. If the interruption of a run is due to operating error 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

Astern Endurance

Economy

DURATION

_{4 hours}

30 Minutes

_{4 hours}

POWER LEVEL

Max Continuous

Rating

Max Astern

Continuous Rating

Specified

Continuous Service

Rating

CRITICAL MEASUREMENTS

Power

Torque/RPM

Power Level & Fuel

Consumption

INTERVAL FOR CRITICAL

MEASUREMENTS

15 Minutes

10 Minutes

15 Minutes

SUPPORTING DATA (As

pertinent)

Torque

Torque

Same as Ahead

Endurance

RPM

RPM

Plus: Aux Load

Prop Pitch

Prop Pitch

Fuel

PRPLS Motor KW

PRPLS Motor KW

PRPLS Motor KW

Rack Position

Rack Position

Max Cylinder Firing

Pressure

Fuel sample for

heating value

analysis

Air Intake Temps

PLANT CONTROL

PARAMETER

Power or RPM

Torque RPM

Power or RPM

MEANS OF CONTROL

Remote Control

System

Remote Control

System

Remote Control

System

Endurance and economy Trials may be concurrent if power level is the same. If power levels

differ, the duration of the Economy Trial may be reduced to two hours if it follows the Endurance

Trial immediately (alternatively recommended).

b

To be in accordance with Classification Society requirements.

c

Endurance testing using an alternate fuel or secondary propulsion system may be required.

d

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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 Design a Max Continuous b Service a

CRITICAL MEASUREMENTS Power Torque/RPM Power Level & Fuel Consump

INTERVAL FOR CRITICAL MEASUREMENTS

15 Minutes 10 Minutes 15 Minutes SUPPORTING DATA (As pertinent) Torque Torque Same as Ahead

Endurance

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 CRITICAL

MEASUREMENT AVERAGES FROM LEVEL SPECIFIED

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

Minus 2% Minus 10% Minus 5%

FLUCTUATION OF INDIVIDUAL DATA 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

System

Remote Control

System

Remote Control

System

Endurance and economy Trials may be concurrent if power level is the same. If power levels differ, the duration of the Endurance Trial may be reduced to two hours if it follows the Economy Trial immediately (alternatively recommended).

b

To be in accordance with Classification Society requirements.

c

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2.2 PROPULSION PLANT ECONOMY TRIALS

2.2.1 Purpose

The primary purpose of Economy Trials is to determine fuel consumption. An ancillary purpose is to establish an RPM/SHP relationship under trial conditions.

2.2.2 Operating Conditions

Uniform 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 be allowed 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 5 degrees rudder. The test director must be informed when ship navigation necessitates the change in ship’s speed or the use of more than 5 degrees rudder. An announcement should be made to suspend and/or resume affected measurements when under these conditions.

2.2.3 Frequency of Observations

Unless otherwise agreed, observations and instrument readings should be taken at fifteen minute intervals. 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 sampling techniques which will be averaged at 15-minute intervals. See Tables 2 and 3 for reading intervals for important data.

2.2.4 Communication

Visual 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.

Trial observations should include all pertinent time intervals, pressures, temperatures, flow rates, levels, revolutions, combustion conditions, and other characteristics of operation, as may be required to satisfy the trial objectives.

For information concerning trial instrumentation, see Section 5.0, Instruments and Apparatus for Ship's Trials.

For data reporting forms listing recommended trial observations, see Section 6.0, Trial Data and Report.

(b) Power.

Method of determining shaft power should be as agreed before trials.

Suitable measuring apparatus, methods of measuring, and methods of computing shaft power are given in Section 5.0, Instrumentation and Apparatus for Ship's Trials, but it is not intended to limit or restrict the use of the measuring equipment to types described therein.

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

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

(c) Revolutions.

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

(d) Fuel Measurements.

Measurements of fuel quantity should be made by flow rate meters, which should be calibrated before and after trials and the calibration correction applied to the observed trial 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 be obtained from calibrated test gages and thermometers installed for the trial. Data from ship's gages, thermometers and instruments may be used for trial purposes provided these instruments have been calibrated and set to read correctly in the operating range.

Acceptable instruments for time measurements are described in Section 5.0, Instruments and 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 data onboard. Information from these systems can be useful during trials if high accuracy under trial conditions is known. Data points from sea trials can be used to verify the accuracy of these systems to assist the operator in optimizing performance.

2.2.6 Fuel Rate Data Required

The fuel rate for all purposes should be expressed in grams per shaft power per hour or other agreed standard units for each trial run. See Tables 17 -18 of Section 4 Standardization Trials, for Data Sheets. The fuel rate should be determined from averages of readings recorded at fifteen (15) minute intervals and data obtained from other sources as indicated in the following:

a) Fuel meter readings at start and at end of each trial interval. b) Fuel meter correction from meter calibration curve.

c) Fuel temperature at the meter.

d) Gravity of fuel related to specific gravity of water at 60°F. (for liquid fuels)

e) Table or plot of weight/volume for the range of metering temperature expected, applicable to the gravity of fuel being burned. (for liquid fuels)

f) Higher heating value of fuel from laboratory tests or lower heating value as agreed or specified.

g) Average shaft power (kW) for each trial interval. h) Fuel chemistry, if specified.

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Note: Fuel Properties should be determined by post trial analysis of a thorough mix of fuel samples taken 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 as mass per unit time so that d) and e) above are not required.

2.2.7 Trial Report

See tables in Section 6.0, Trial Data and Report.

2.3 PROPULSION PLANT AHEAD ENDURANCE TRIALS

2.3.1 Purpose

The 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 should include 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 for endurance and economy trials, they may be conducted concurrently when specifications for both are the same for shaft power, period of run time, and fuel. For Endurance Trials the emphasis is on attaining 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 levels are 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 the details thereof are subject to agreement between the parties involved and are not covered by this section.

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

2.3.2 Measurements and Instrumentation

Economy Trial instrumentation and data systems are generally adequate for Endurance Trials. When both trials are specified, the requirements and discussions of paragraph 2.2 apply. When only Endurance Trials are specified, paragraph 2.2 is applicable, except that special fuel meter calibration may not be required and power level may be determined without use of a torsionmeter as discussed below. However, it is recommended that a torsionmeter be used for at least the first ship of a class so that corrections to the alternative methods discussed below can be developed both for future trials and for use in checking service performance.

When a torsionmeter is fitted, power should be derived from the average torque and RPM for the trial period as set forth in paragraph 2.2. However, upon agreement or by specification, torsionmeters may be omitted and power approximated from one or more of the following:

1. Propeller revolutions per minute with model test data.

2. On ships with direct drive, prime mover parameters and conditions, and manufactu’er's shop test or design data.

3. On ships with electric drive, electrical input to the propulsion motor(s) with manufacturer's data on motor efficiency and power consumption of shaft-driven auxiliaries.

Even when trial power is determined by use of a torsionmeter, a comparison should be made with power derived from engine data, particularly where a torsionmeter is not to be permanently fitted.

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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 of the propulsion plant at specified operating conditions as contractually required or agreed. This should include specific shaft power or revolutions per minute for a prescribed period of time. An ancillary benefit is proving the adequacy of piping supports, and equipment under severe vibratory conditions.

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-screw ship is under sternway, often prevents steady propulsion plant operation. It is therefore advisable to establish 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 from hard over will not result in rudder torque exceeding the maximum specified. In such cases the maximum 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 Report

See tables in Section 6.0, Trial Data and Report.

2.5 SPECIAL CONSIDERATIONS FOR DIESEL AND OTTO

CYCLE ENGINE PROPULSION PLANT TRIA LS

This section addresses sea trial related tests which are peculiar to propulsion plants utilizing diesel and Otto cycle engines and amplifies some areas which are covered generally in paragraphs 2.2 through 2.4 above. A major purpose of the Economy and Endurance trials is to provide base-line operating data for the entire plant, and the sea trials should be planned and carried out with this in mind. Plants designed to operate on more than one fuel should be operated on each of the fuels during trials to obtain data appropriate for operation on each fuel.

2.5.1 Auxiliary Components

The following are examples of auxiliary components which may be part of a diesel plant:

a. Turbochargers, reciprocating or gear type blowers, or other sources of combustion or scavenging air pressure.

b. Engine-driven lube oil, fuel or cooling fluid pumps. c. Independently driven generators, pumps or centrifuges.

d. Power transmission elements including gears, couplings, clutches, etc. e. Waste heat boilers and/or auxiliary boilers.

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Special agreements should be made prior to trials for observing the performance of the auxiliary components 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 be obtained.

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 consuming equipment in operation should be measured separately.

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

2.5.4 Fuel Rate Data Required

Same 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 engine manufacturer:

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 test devices should be provided on trials to accurately measure these variables.

2.5.5 Power

When torsionmeters are not required to be fitted, brake power for diesel engines may be estimated by the following methods:

a) Rack Position - Brake power may be closely approximated by careful observations of fuel injection rack positions and comparison of these with data taken during shop tests where output is measured directly on a water or electric brake or equivalent. For maximum accuracy it is necessary that shop tests and ship's trials utilized comparable fuel.

b) Slip Coupling - On installations using a slip type coupling, the torque transmitted can be closely approximated by comparing the engine RPM and shaft RPM with slip data supplied by the coupling manufacturer.

c) Indicator Cards Indicator cards or equivalent may be taken on each cylinder, and the brake KW (BKW) may be computed with very good results for low or medium speed units. Engine efficiency data, other correlating data, or sample correction curves are also needed with the indicator card data to compute BKW.

Each of the above methods may be used to determine brake power. An agreed allowance for gear or coupling losses must be applied to obtain shaft power, if these elements are in the power train.

When a torsionmeter is fitted, the correlation between the shaft KW (SKW) determined from the torsionmeter and the BKW determined from engine data should be established during the trials.

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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 an Emission Control Area (ECA), the switching from one fuel type to the other and then back again, are to be demonstrated at the highest power level possible to demonstrate the limits at which fuel

switching 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 specified operational conditions. Fuel consumption of various components such as auxiliary engines or boilers would 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 heating value. 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 TURBINE

PROPULSION PLANT TRIALS

This section covers sea trial related items which are peculiar to gas turbine propulsion plants. This guide 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 Components

The following are examples of auxiliary components which may be part of the gas turbine plant: a) Precoolers, intercoolers, and after coolers.

b) Reheaters, regenerators, and recuperators. c) Fuel conditioning equipment.

d) Independently powered generators and pumps. e) Control equipment and safety devices.

f) Power transmission elements including gears, clutch, shaft brake, coupling, controllable pitch propeller, etc.

g) Waste heat or independently fired boilers. h) Anti-icing and bleed air systems.

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

2.6.2 Fuel Rate Data Required

Fuel rate corrections for variations from design values of the following should be provided by the gas turbine engine manufacturer:

a) Inlet air temperature. b) Inlet air moisture content. c) Power turbine RPM. d) Inlet air pressure.

19 e) Exhaust pressure.

These corrections are required to properly evaluate gas turbine performance. Suitable test devices should be provided on trials to provide the necessary data. Barometric pressure and relative humidity of the outside air should be recorded to permit evaluation of air inlet and exhaust duct systems. The shipbuilder, however, is responsible for designing the air inlet and exhaust systems to meet design turbine 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 the engine RPM, internal gas pressures and temperatures and/or fuel oil flow with sufficient accuracy for endurance trial purposes. Sample reference curves and correction factors will be very useful to develop estimates.

When torsionmeters are required to be fitted, a correlation should be established during trials between the 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 DRIVE

PROPULSION PLANT TRIALS

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

2.7.1 Auxiliary Components

The following are examples of auxiliary components which may be part of the electric drive propulsion plant:

a) Heat exchanger units.

b) Independently powered pumps. c) Attached pumps.

d) Independently powered fans

e) Control equipment and safety devices.

f) Power transmission elements including gears, clutches, shaft brakes, couplings, controllable pitch propeller, etc.

Special agreements should be made prior to trials for observing the performance of the auxiliary components listed above.

2.7.2 Power

Power output from the propulsion motor can be determined from the torsionmeter when installed or from the instruments if not installed. Agreements should be made prior to trials regarding instrumentation to be used for power determination during trials.

2.7.3 Trial Data and Report