ITTC Guidelines Conduct of S P Trials V0.5 ModHSVA

ITTC – Recommended

Procedures and Guidelines

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Speed and Power Trials

Part I Preparation and Conduct

Effective Date

2012

Revision

0.5

Updated / Edited by Approved

Specialist Committee on

Performance of Ships in Service

of the 27th ITTC

27th

ITTC 2012

Date 2012 Date 2012

Table of Contents

1. PURPOSE .................................................................... 2

2. DEFINITIONS ............................................................ 3

3. RESPONSIBILITIES ................................................. 3

3.1 Shipbuilders Responsibilities ................................ 3

3.2 The Trial Team....................................................... 4

4. TRIAL PROCEDURES .............................................. 4

4.1 Parameters that should be logged ......................... 4

4.2 Primary parameters ............................................... 4

4.3 Other associated measurements ............................ 5

4.4 General information............................................... 5

4.5 Important aspects with regard to the

measurements ......................................................... 6

4.5.1 Ship track and Speed over Ground ..................... 6

4.5.2 Torque................................................................. 6

4.5.3 Wind measurements ............................................ 6

4.5.4 Depth measurement ............................................ 6

4.5.5 Wave measurements ........................................... 6

4.5.6 Density and temperature at the location of the

measurements ..................................................... 7

4.5.7 Current ................................................................ 7

5. DATA ACQUISITION ............................................... 7

5.1 General data ........................................................... 7

5.2 Data on each run .................................................... 7

5.3 Automated data acquisition................................... 8

5.4 Manual data acquisition ........................................ 8

6. TRIAL PREPARATIONS ........................................ 11

6.1 Step 1: Installation & Calibration ....................... 11

6.2 Step 2: Trial agenda and pre-trial meeting ........ 11

7. TRIAL BOUNDARY CONDITIONS ...................... 12

7.1 Location ................................................................. 12

7.2 Wind ...................................................................... 12

7.3 Sea State ................................................................ 12

7.4 Water depth .......................................................... 13

7.5 Current .................................................................. 13

8. SHIP CONDITION ................................................... 13

8.1 Displacement ......................................................... 13

8.2 Trim ....................................................................... 13

8.3 Hull & Propeller ................................................... 13

9. TRIAL PROCEDURES ............................................ 14

9.1 Trial preparations ................................................ 14

9.2 The trial trajectory ............................................... 14

9.3 Run Duration ........................................................ 14

9.4 Trial Direction ...................................................... 14

9.5 Steering.................................................................. 15

9.6 Approach ............................................................... 15

9.7 Number of Speed runs.......................................... 15

9.8 Test sequence S/P trials ........................................ 16

10. REPORTING ............................................................. 16

REFERENCES ................................................................ 17

APPENDIX I .................................................................... 18

General Ship and Trial Conditions Reported ............... 18

APPENDIX II .................................................................. 19

Beaufort Scale of Wind ........................................ 19

APPENDIX III ................................................................. 21

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Part I; Preparation and Conduct

Effective Date

2012

Revision

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1. PURPOSE

The primary purpose of speed trials is to

determine ship performance in terms of speed,

power and propeller revolutions under pre-

scribed ship conditions, and thereby verifying

the satisfactory attainment of the contractually

stipulated ship speed and to provide the ship

speed for the calculation of the Energy Effi-

ciency Design Index (EEDI) as required by

IMO.

The present Guidelines concern the prepa-

ration and execution of speed trials and have

been defined by the 27th

ITTC Specialist

Committee on the Performance of Ships in

Service. In this work the Committee took into

account:

Recommendations 23rd

ITTC 2002; Ref [1],

ISO 19019, 2002; Ref [2],

ISO 15016, 2002; Ref [3],

STA-JIP 2006; Ref [4].

For the analysis and reporting of speed tri-

als, reference is made to Part II of these Guide-

lines.

The purpose of this document which is ap-

plicable to commercial ships of displacement

type is:

to prepare and document,

to define the responsibility of each party

involved,

to specify the vessel condition,

to specify the limiting weather and sea

conditions,

to install and calibrate trial instrumentation,

to specify the measurements required and

to define the data acquisition and recording.

The contracted ship speed and the speed for

EEDI should be determined for the stipulated

conditions which usually are for the ship at the

specified draft (contract draft or EEDI draft)

and for ideal conditions i.e. no wind, no waves,

no current, deep water, and smooth hull and

propeller surfaces.

Normally such stipulated conditions cannot

be expected during the actual trials. In practice,

certain corrections for the environmental condi-

tions should be considered, as for water depth,

wind, waves and deviating ship draught. For

this purpose not only the shaft power and ship

speed are measured but also relevant ship data

and environmental conditions during the S/P

trials.

All trial procedures and measurements

should be conducted in such a way that the

speed at Contract power and EEDI power is de-

rived within 0.1 knots and the shaft power

within 2%.

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2. DEFINITIONS

Brake Power: Power delivered by the out-

put coupling of the propulsion machinery.

Docking Report: Report that documents

the condition of the ship hull and propul-

sors (available from the most recent dry -

docking).

Double run: two speed runs at the same

power setting on reciprocal heading.

EEDI: Energy Efficiency Design Index as

formulated by IMO.

Ideal conditions: ideal weather and sea

condition; deep water, no wind, no waves

and no current.

Propeller Pitch: the design pitch also for

controllable pitch propellers.

Running Pitch: the operating pitch of a

CPP.

Shaft Power: Net power supplied by the

propulsion machinery to the propulsion

shafting after passing through transmission

devices and after power for all attached

auxiliaries has been taken off.

Ship Speed: Speed that is realized under

the stipulated conditions. “Contract Speed”

refers to the contractual agreed conditions.

“EEDI Speed” refers to the conditions

specified by IMO.

Speed run: ship track with specified

course, distance and duration over which

ship speed and shaft power are measured.

Trial Agenda: Document outlining the

scope of a particular Speed/Power trial.

This document contains the procedures on

how to conduct the trial and table(s) por-

traying the runs to be conducted.

Trial Log: For each run, the log contains

the run number (type of manoeuvre) ap-

proach speed by log, approach shaft speed,

times when the manoeuvres start and stop,

and data as described in chapter 4.

Verifier; third party responsible for verifi-

cation of the EEDI.

3. RESPONSIBILITIES

3.1 Shipbuilders Responsibilities

The Shipbuilder has the responsibility for

planning, conducting and evaluating the tri-

als.

Speed / Power Trials may be conducted by

organisations acknowledged as competent

to perform those trials, as agreed between

the Shipbuilder and the Ship Owner.

The Shipbuilder has to provide all permits

and certificates needed to go to sea.

The Shipbuilder is responsible to ensure

that all qualified personnel, needed for op-

erating the ship and all engines, systems

and equipment during the trials are on

board.

The Shipbuilder is responsible to ensure

that all regulatory bodies, Classification

Society, Owner, ship agents, suppliers, sub-

contractors, harbour facilities, delivering

departments of provisions, fuel, water, tow-

ing, etc., needed for conducting the sea tri-

als, have been informed and are available

and on board, when required.

It is the Shipbuilder’s responsibility that all

safety measures have been checked and that

all fixed, portable and individual material

(for crew, trial personnel and guests) is on

board and operative.

It is the Shipbuilder’s responsibility that

dock trials of all systems have been exe-

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cuted and all alarms, warning and safety

systems have checked.

It is the Shipbuilder’s responsibility that an

inclining test has been performed and/or at

least a preliminary stability booklet includ-

ing S/P trials condition has been approved,

in accordance with the 1974 SOLAS Con-

vention.

The Shipbuilder is responsible for the over-

all trial coordination between the ship's

crew, Trial team and the Owner representa-

tive. A pre-trial meeting between the Trial

Team, Owner and the ship’s crew will be

held to discuss the various trial events and

to resolve any outstanding issues.

The Shipbuilder has, to arrange for divers

to inspect the ship’s hull and propellers if

necessary.

The Trial Leader is the duly authorised

(shipbuilder’s representative) person re-

sponsible for the execution of all phases of

the Speed/Power trials including the pre-

trial preparation. The Trial Leader main-

tains contact with the Owner’s representa-

tive and the Trials Team on the preparation,

executing and results of the trials.

3.2 The Trial Team

The Trial Team is responsible for correct

measurements and reporting of the trials ac-

cording to this document. The Trial Team is

also responsible for the analysis of the meas-

ured data to derive the ship speed and power at

the stipulated conditions. This analysis should

be conducted in compliance with ITTC Guide-

lines for Analysis and Reporting of Speed Tri-

als, 2012.

The Trial Team is responsible for the fol-

lowing:

a. Conduct ship inspection,

b. Provide, install and operate all required

trial instrumentation and temporary ca-

bling,

c. Provide the ship master and Owner’s

representative with a preliminary data

package and preliminary analysis before

debarking,

d. Provide a final report after completion

of the trials in accordance with Chapter

10.

4. TRIAL PROCEDURES

4.1 Parameters that should be logged

In this chapter an overview is given of the

parameters that influence the trial speed. All

these parameters should be recorded as accu-

rately as possible.

For this purpose a division has been made

between primary and secondary parameters. For

each of the parameters the preferable measure-

ment methods are given.

4.2 Primary parameters

The primary parameters to be measured and

the accepted measurement devices are given in

Table 1.

Acceptable measurement

devices

Unit

Ship Track DGPS [Latitude,

Longitude]

or [m]

Speed over the

Ground

DGPS Knots

Shaft Torque

or Shaft Power

Torsion meter with strain

gauges or better,

calibrated permanent

torque sensor.

Power to be calculated

from torque and RPM

[kNm],

[kW]

Shaft RPM Pick-up, optical sensor,

ship revs counter

[ RPM]

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Propeller pitch Bridge replicator

Time GPS Time, Stopwatch [s]

Water depth Ship echo sounder +

nautical charts

[m]

Ship heading Gyro compass, or DGPS [deg]

Relative wind Ship anemometer, external

anemometer

[m/s],

knots, [deg]

Wave height &

direction

Wave measuring device

(i.e. radar, scanner. etc),

Wave buoy, observation

by multiple observers

[m], [deg]

Draughts Physical observation and /

or calibrated draught

gauges

[m]

Table 1 Primary parameters

4.3 Other associated measurements

Sea water

density

Salinity sensor,

Conductivity Density

Temperature (CDT)

sensor

Ρ [kg/m^3]

Seawater

temperature

Thermometer, CDT

sensor

[ºC]

Air temperature Thermometer [ºC]

Air pressure Barometer [hPa], [mBar]

Table 2 Other associated measurements

Other associated measurements should be

carried out at the trial site

4.4 General information

Prior to the trial, the data specified below shall

be recorded, based on measurements where

relevant:

Hull condition

Last date of cleaning hull

Hull appendages and Rudder

Geometry

Type

Rate of Movement during speed

trials

Wind fetch

Height of wind meter above

waterline

Frontal wind area

Propeller(s)

Type (FPP/CPP)

Pitch (FPP)

Direction of rotation

Number of blades

Shaft(s)

G modulus

Diameter (inside)

Diameter (outside)

Shaft material

properties to be

provided by yard

(shaft supplier data)

Table 3 General information

Model test information

The quality and accuracy of model tests

play a large role in the outcome of full scale

trials. Often sea trials are carried out in ballast

condition, whereas the contractual condition

normally is defined in loaded design condition.

For the conversion from ballast trial results to

loaded condition the difference between the

ballast and loaded model test curves is used.

Therefore an accurate model test and validated

consistent extrapolation method to full scale is

required.

For the analysis of the speed trials i.e. the

correction of rpm, it is recommend that the

model tests data include the results of propeller

load variation measurements. If this informa-

tion is not available an open water diagram of

the propeller should be provided for the Kt/J2

method.

Based on ITTC recommendations the

model tests should be conducted according to

the following procedures:

1) Model tests should be conducted at the con-

tract draft & trim, the EEDI draft & trim as

well as the trial draft & trim.

2) Model tests should be conducted according

to the ITTC Recommended Procedures for

Resistance and Propulsion Model Tests,

Ref [5].

3) For all drafts and trims the same methods,

procedures and empirical coefficients

should be used to extrapolate the model

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scale values to full scale. In case other

methods, procedures or empirical coeffi-

cients are used, these should be docu-

mented in full detail and justified by means

of full scale speed-power trial data for the

specific ship type and size.

4) The model test report should be transparent

and give sufficient information to enable a

third party institute and the EEDI verifier to

check the model test results using the above

ITTC procedure or its own extrapolation

method. This means that in the model test

report, the measured data, the predicted full

scale data and a detailed description of the

extrapolation method and the coefficients

used should be given.

4.5 Important aspects with regard to the

measurements

4.5.1 Ship track and Speed over Ground

The speed is to be measured by a global po-

sitioning system such as GPS. The GPS system

should operate in the Differential mode to en-

sure sufficient accuracy; i.e. the speed should

be measured within 0.05 knots. The position

and speed should be monitored and stored con-

tinuously.

4.5.2 Torque

Shaft torque should be measured by means

of strain gauges on the shaft for which the zero

offset is determined just prior to the trial. The

measurement system should be certified for

measurements on a test shaft with a bias error

smaller than 1% so that an overall bias error

smaller than 2% (on board of the actual ship)

can be achieved. Alternative torque measure-

ment devices with a certified accuracy equal to

or better than the above figures are acceptable.

The calibration of the torque measurement

should not be altered during the Speed/Power

trials.

In case shaft torque measurement is not

possible, an alternative power measurement

method recommended by the engine manufac-

turer and approved by Owner and Verifier is

acceptable.

The shaft material properties i.e. the G-

Modulus as specified by the shaft supplier

should be provided by the yard. The shaft di-

ameter used in the power calculation should be

derived from the shaft circumference in-situ

measured at the location of the torque instru-

mentation.

4.5.3 Wind measurements

The ship’s own sensor or an external wind

meter on board can be used. The wind meter

should be as clear as possible from the super-

structure. Continuous recording of the wind

during each run is recommended.

4.5.4 Depth measurement

This can be done by using the ship echo

sounder. It is important that the echo sounder is

calibrated before the speed run in combination

with the check of the depth on the charts and

that the vessel draught is taken into account.

Continuous recording of water depth is rec-

ommended.

4.5.5 Wave measurements

Preferably the wave height, wave period

and direction of waves due to wind and swell

should be determined using instruments. Use

can be made of wave buoys or instruments on-

board the ship such as a wave radar and wave

scanner. Although less accurate, wave condi-

tions may also be determined from observa-

tions by multiple observers, including an ex-

perienced captain.

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4.5.6 Density and temperature at the location

of the measurements

The local seawater temperature and density

at the trial site need to be recorded to enable

the calculation of ship’s displacement and cor-

rections with regard to viscosity. The water

temperature should be taken at sea water inlet

level. Air temperature should be measured at

the trial location using a calibrated thermome-

ter and barometer.

4.5.7 Current

Current speed and direction shall be ob-

tained as part of the evaluation of each run.

5. DATA ACQUISITION

During the speed/power trial accurate re-

cording of the speed and power relationship is

of great importance.

Next to this an accurate quantification of

the boundary conditions is necessary since the

ship’s speed and powering characteristics are

extremely sensitive to conditions such as ship

and propeller condition, ship displacement,

shallow water effects, sea state and wind veloc-

ity. Consequently, these factors should be

monitored and documented to the greatest ex-

tent possible.

During the speed/power trial two types of

data acquisition should be used: Automated ac-

quisition by means of a data acquisition system

(measurement computer), and information that

is noted down by means of a log sheet. The ob-

jective should always be to record as many pa-

rameters as possible by means of the measure-

ment computer in order to increase the level of

accuracy of the trials.

In general, data to be acquired can be di-

vided into general data which is applicable to

all speed runs and specific data that is varying

throughout every run.

5.1 General data

Prior to the trial, the data specified below

shall be recorded, based on measurements

where relevant:

Date

Area of trial

Weather

Water temperature and density

Air temperature

Height of wind instrument above waterline

Fore, amidships and aft draughts

Displacement

It is recommended to record the absolute

wind speed and direction by shore based sta-

tion(s) or as measured directly prior to and af-

ter finalising the speed trials while the vessel is

stopped.

5.2 Data on each run

Clock time at commencement (UTC)

Time elapsed over the measured distance

Ships heading

Ship’s speed over the ground

Ship’s course over ground

Propeller rate of revolutions

Propeller shaft torque and/or power

Propeller pitch in case of CPP

Relative wind velocity and direction by

anemometer

Mean wave period, significant wave height

and direction of waves (Wind Seas)

Mean wave period, significant wave height

and direction of waves (Swell)

Mean water depth

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5.3 Automated data acquisition

The acquisition system should be able to

record time histories of the measurements de-

scribed in chapter 4.3 in order to assure quality

control and to provide information that will al-

low for the development of uncertainty analysis.

Minimum data for acquisition system

An overview of minimum parameters that

should be recorded during each run of the

speed trial is given below.

Date

Run number

Time

Propeller shaft torque or power

Propeller shaft rpm

Pitch of CPP

Ship positional data

Ship heading

Ship’s speed over the ground

Water depth

Relative wind direction

Relative wind speed

Requirements of data acquisition system

The data acquisition system should be able

to:

Record all available parameters simultane-

ously.

Perform a time trace recording with a sam-

pling rate of at least 1 Hz.

Display time traces of all trial parameters

Calculating statistics (Mean, min, max,

standard deviation).

At the end of each run the data acquisition

system should be able to present all recorded

time histories to evaluate the quality and con-

sistency of the acquired trial data and be stored

for on-line graphical presentation.

Furthermore the acquisition system should

be able to present the following statistical val-

ues for each of the measured data:

1. Trial start Time

2. Number of samples taken

3. Maximum value

4. Minimum value

5. Average value

6. Standard deviation

Filtering of the run data is recommended to

avoid “spikes” in the recorded time histories.

ITTC suggests the use of Chauvent’s criterion

that provides a ratio of maximum acceptable

deviation to precision index as a function of the

number of readings, (N). Readings are auto-

matically rejected from use in the data analysis

when they fall outside of the selected mean

value bandwidth.

Location of data acquisition system

The data acquisition system should be lo-

cated on the bridge.

5.4 Manual data acquisition

For those parameters that cannot be ac-

quired automatically by means of the data ac-

quisition system, manual acquisition is required

with use of a log sheet

The log sheet is important for two aspects:

1. First of all to complete the dataset

2. Secondly to provide a backup for the auto-

mated measurements and give a written

overview of the measurements.

It is important that the parameters that are

varying in time will be recorded every few

minutes so that the average can be determined

over the run period.

An example of a log sheet that can be used

is shown in Figure 1 and given in further detail

in Appendix III. The sign conventions to be

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used for wave and wind direction are presented

in Figures 2, 3 and 4.

Figure 1 Example of a log form

Figure 2 Sign conventions

Figure 3 Sign convention for wind directions

The wind direction is defined as the direc-

tion where the wind is coming from.

0 degrees on the bow and positive to starboard

(clockwise).

Input parameters:

Heading: Heading of the ship [deg]

VWR: Relative wind speed [knots]

ψWR: Relative wind direction relative to

the bow, ship fixed; 0 means

heading winds [deg]

VG: Ship speed over ground [knots]

Computed parameters:

ΒWT: True wind angle in earth system

[deg]

VWT: True wind speed [knots]

Ship name: Date:

Tfwd m Tair ⁰ C outer dia D1 mm

Taft m Twater ⁰ C inner dia D2 mm

Displacement tons ρwater kg/m3 steel type N/mm2

Run No. Time DescriptionForward /

Return runHeading Speed (SOG) Power Revs Speed Direction Height Direction Period UKC

[-] [-] [-] [F / R] [deg] [kn] [kW] [RPM] [kn] [m/s] [deg] [m] [deg] [s] [m]

Relative windPropeller Waves visual

Speed - Power Trials Log Form

Ship

m

Height of

anemometer

above water:

Environment Propeller shaft

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Figure 4 Sign convention for wave directions

The wave direction is defined as the direc-

tion where the waves are coming from.

0 degrees on the bow and positive to starboard

(clockwise).

Input parameters:

Heading: Heading of the ship [deg]

HW1/3: Significant wave height [m]

α: Angle between ship heading and

wave direction relative to the bow;

0 means heading waves [deg]

VG: Ship speed over ground [knots]

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6. TRIAL PREPARATIONS

The success of the speed/power trial largely

depends on the preparations of the trial. In this

chapter the most important steps are summa-

rized.

6.1 Step 1: Installation & Calibration

Assemble all trials instrumentation in the

configuration that will be used on the ship. Test

the instrumentation system for malfunctioning

or any other complications.

Apart from the obvious signals such as

shaft torque, rpm and DGPS, it is important to

check:

1. Gyrocompass heading

2. Relative wind direction

3. Relative wind speed

4. Log speed

5. Propeller pitch of each propeller

6. Ship’s draught measurement system

7. Water depth measuring system

All shipboard signals to be recorded during

the trials should be calibrated after the instru-

mentation installation is completed and prior to

the S/P trials. For this purpose the sensors

should be cycled throughout the full operating

range of the system.

This is accomplished by:

Slewing the gyrocompass

Changing the propeller pitch

The ship’s draught measurement system

needs to be verified prior to getting underway

for trials, by directly reading all draught marks

seawater temperature, specific density and the

internal draught system at the same time.

The torque measurements system should be

corrected for any zero offset. As part of the S/P

trial preparation, the torsion meters zero torque

readings should be determined since there is a

residual torque in the shaft, which is resting on

the line shaft bearings. The torsion meter zero

setting to be done according its makers’ in-

structions.

Checks of the torque measurement calibra-

tion should be made just before and after the

speed trials.

As part of the pre-trial calibration for a ship

equipped with controllable pitch propellers the

following procedures should be as following:

1. Prior to dock-out the Oil Distribution

mechanism showing the propeller pitch

should be checked for zero pitch;

2. Check zero pitch reading in the measure-

ment system against the mechanical reading

in the Oil Distribution box;

3. Determine the maximum ahead pitch, de-

sign pitch, and maximum astern pitch and

then adjust the ship indicators to reflect the

measurement. Determine the corrections to

account for changes in pitch due to shaft

compression as thrust increases and tem-

perature effects on the propeller pitch con-

trol rod.

4. Verify the weight of the propulsor and hub

from the manufacturer’s specifications for

making thrust measurement corrections.

An important deliverable of this stage will

be a document describing the test set-up, and

the calibrations including evidence of the cali-

brations that have been carried out.

It is important to note that there are two

stages to consider in performing instrumenta-

tion checks; the pre-trial check procedures and

the post trial check to verify the calibration re-

sults.

6.2 Step 2: Trial agenda and pre-trial

meeting

Before departing, a pre-trial meeting should

be held to fix the S/P trial program and S/P trial

agenda.

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During the meeting two items should be ad-

dressed.

Approval of the trial agenda;

Approval of the procedures that will be

used to calculate the trial speed and to de-

liver the speed trial report i.e. Part II of

these Guidelines.

The trial agenda is a document prepared by

the yard, outlining amongst others the scope of

a particular Speed/Power trial. This document

contains the procedures on how to conduct the

trial and table(s) portraying the runs to be con-

ducted. It outlines the particular responsibilities

of the Trial Leader, Trials Team, Ship’s crew/

Shipbuilder, and the Owner’s representative.

The scope of the S/P trials shall be in line with

this document.

7. TRIAL BOUNDARY CONDITIONS

During the S/P trial there are many condi-

tions that deviate from the contract condition.

The objective during the S/P trial is to keep the

number of influencing factors as limited as

possible.

This is important since although there are

correction methods to correct for certain devia-

tions from the contract condition, these meth-

ods are only valid up to certain limits.

In order to arrive at reliable S/P trial results

the boundary conditions should not exceed the

values given in this chapter.

7.1 Location

High wind and sea state in combination

with a wrong course, can force the use of ex-

cessive rudder deflections to maintain heading,

and thus cause excessive fluctuations in shaft

torque, shaft speed and ship speed.

The S/P trial should be conducted in a loca-

tion where the environmental conditions are

constant and have only a small possible impact

on the vessel in order to avoid unexpected en-

vironmental effects in the S/P trial results.

This means that the speed trial range should

be located in a sheltered area (i.e. limited wind,

waves and current). Furthermore the area

should be free from hindering small boat traffic

and commercial traffic.

7.2 Wind

During the S/P trial the wind speeds should

not be higher than:

Beaufort number 61, for vessels with

PPL >100 m, or

Beaufort number 5, for vessel with

PPL ≤100 m

7.3 Sea State

The total wave height H , which is the sum

of significant wave heights of sea W1/3H and

swell s1/3H , shall satisfy the following:

for PPL >100 m: the lower value of

H ≤ 0.015 ppL or maximum 4 m.

for PPL ≤100 m: H ≤ 1.5 m

Where: 2 2

W1/3 s1/3H H H

In addition to the above limitations, it is re-

quired that when the significant wave height H

1 The Beaufort scale is given in appendix II

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exceeds 3.0 m (for vessels with PPL >200 m),

the actual wave spectrum encountered during

the trial should be measured accurately i.e. the

difference between actual and measured sig-

nificant wave height should be less than 10%.

7.4 Water depth

There are correction methods that compen-

sate for shallow water; however it is better to

avoid the corrections by a proper choice of the

S/P trial location. The minimum water depth at

which no correction for shallow water is

needed, can be calculated using the larger of

the values obtained from the two equations (ref.

[1]):

3h B T and 2

S2.75V

hg

Furthermore significant variations in the

bottom contours should be avoided. The actual

water depth during each S/P trial run should be

read from the ship instruments and documented

in the trials log.

7.5 Current

Areas with known large current variations

should be avoided.

8. SHIP CONDITION

8.1 Displacement

The ship’s displacement should be within

2% difference of the actual required displace-

ment. If model test results are used for the

analysis of the speed trials, the displacement

used in the model tests should be within 2% of

the displacement during the trials.

Draft, trim and displacement of the S/P tri-

als should be obtained by averaging the ship

draft mark readings. The ship should be

brought into a loading condition that is as close

as possible to contract condition and/or the

condition at which model tests have been car-

ried out.

The loading condition should be confirmed

at zero forward speed. Draft, trim and dis-

placement should be obtained at the beginning

of the trial. For this purpose the draught gaug-

ing system should be tested and calibrated prior

to the trials in port by direct draft readings both

port and starboard in conjunction with the load-

ing computer. The trial team will verify the ac-

curacy of the draught gauging system prior to

the Speed/Power trials.

Displacement should be derived from the

Bonjean data or using quadratic equations with

hydrostatic data taking into consideration the

hog/sag using the draft data and the density of

the water.

8.2 Trim

Trim shall be maintained within very nar-

row limits. For the even keel condition the trim

shall be less than 1.0% of the mid-ships

draught. For the trimmed trial condition, the

immergence of the bulbous bow should be

within 0.1 m of the model test condition,

whereas the displacement should be within 2%

of the displacement of the model tested condi-

tion.

8.3 Hull & Propeller

The ship should have a clean hull and pro-

peller for the sea trial. Hull roughness and ma-

rine growth can increase the resistance of the

ship significantly but are not corrected for in

speed trials. Therefore it is recommended that

the hull and propeller are cleaned just prior to

the sea trials. The date of last docking and hull

and propeller cleaning are to be documented in

the S/P trials report.

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9. TRIAL PROCEDURES

On the day of the S/P trial and during the

S/P trial a number of prerequisites should be

met in order to arrive at reliable trial results. In

this chapter an overview is given of the mini-

mum requirements.

9.1 Trial preparations

Prior to the speed trials the following items

should be recorded.

Weather forecast

Water temperature and density

Air temperature

Fore, amidships and aft draughts

Displacement

The schedule for the S/P trials should be ar-

ranged such that the trials around the contract

speed/power settings are conducted at daylight,

to ensure a clear observation of the wave con-

ditions during these runs.

Furthermore, it is important to check that

the engine plant line up during the S/P trial is

consistent with normal ship operations.

Before the actual start of the speed trials,

the following actions should be conducted

when the vessel is stopped in the water (within

the schedule of the trials):

1. draught reading as described in section 8.1

2. measurement of absolute wind speed and di-

rection

3. zero setting of shaft torque meter

4. measuring water temperature and density

9.2 The trial trajectory

The S/P trial runs need to be conducted

over the same ground area. For each base

course, each trial run will be commenced

(COMEX) at the same place (within reason).

Figure 5 Path of ship during typical speed/power

manoeuvre

Modified Williamson turns will be executed

between each run to return the ship to the recip-

rocal baseline and to the same ground area, in

which the previous run was conducted. This

procedure is used to avoid different sea states

or different wind conditions. Engine throttles

should not be moved during this period. The

rudder angle used in this manoeuvre should be

such that ship speed and time loss will be

minimised.

9.3 Run Duration

The S/P trial duration should be long

enough in order to accommodate a

speed/power measurement within the required

accuracy. The following minimum run lengths

should be observed:

for speeds of 18 knots and above: 3 nm

for speeds below 18 knots: 2 nm.

Alternatively a run duration of 10 minutes may

be applied.

9.4 Trial Direction

The first run should be headed into the

dominant wave direction.

Consequently once the heading for the

speed run is fixed, and the reciprocal heading

for the return run, the selected tracks should be

maintained very precisely throughout the S/P

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trial. It is imperative that extremely tight con-

trol is exercised during the execution of the tri-

als to minimize as many variables as possible

that could unduly influence the speed power

relation.

9.5 Steering

An experienced helmsman or adaptive pilot

will be required to maintain heading during

each trial run. Minimum rudder angles to be

used while maintaining a steady heading.

During the run, the single amplitude of rud-

der angles shall be within 5 degrees.

9.6 Approach

The S/P trial approach should be long

enough to ensure a steady state ship condition

prior to commencement (COMEX) of each run.

During the approach run the ship should be

kept on course with minimum rudder.

No fixed approach distance can be given. To

verify that the vessel reached the steady ship

condition the measured values of shaft r/min,

shaft torque and ship speed in the control posi-

tion should be monitored. The condition is con-

sidered “Steady” when the ordered r/min(s),

shaft torque (kNm) and the ship speed (kn) are

steady.

Table 4 provides an indication of approach

lengths and corresponding times for various ship

speeds.

Size of

ship

[DWT]

Approach

distance

[nm]

Approach time [min]

15 knots 20 knots 25 knots

50,000 4 – 5 20 15 12

100,000 5 – 7 26 20 16

250,000 8 – 10 40 30 24

500,000 12 – 15 60 45 36

Table 4 Indication of required approach length and

time

9.7 Number of Speed runs

All S/P trials shall be carried out using

double runs, i.e. each run should be followed

by a return run in the exact opposite direction

performed with the same engine settings.

To determine the speed-power curve for the

first vessel of a ship series, a minimum number

of 5 (five) double runs at 4 (four) different

power settings are required.

These runs comprise:

2 (two) double runs at the same power setting

around the Contract Power,

Double runs at the same power setting

around EEDI Power (75% MCR),

Double runs at 2 (two) other power settings

between 65% and 100% MCR.

Two (2) double runs around Contract

Power are required to compensate for tidal cur-

rents.

All runs should be conducted at daylight to

enable a clear observation of the wave condi-

tions.

If the results of the speed trials of the first

ship of a series are acceptable, sister ships (i.e.

ships with identical main dimensions, body

lines and propulsor system) built in that series

by the same yard may be subjected to a reduced

speed trial program. For such sister ships it is

sufficient to conduct 3 (three) double runs:


around the Contract Power,


around EEDI Power (75% MCR),

Double runs at 1 (one) other power setting

between 65% and 100% MCR.

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In case in the trial area the current speed

can be expected to exceed 0.2 (zero point two)

knots, additional double runs around Contract

Power are required to compensate for tidal cur-

rents with a higher accuracy.

For both the first of a series and following

ships, one additional double run for both Con-

tract Power and for EEDI Power should be

conducted in case:

Strong variations in current (i.e. above 0.2

knots) can be expected;

Wave height is around the limiting condi-

tions and significant wave induced motions

are observed.

9.8 Test sequence S/P trials

1. Check displacement by draught reading

fore, amidships at two sides and aft, prior to

the S/P trials in the trial area; Check zero

setting of the torque measurement, measure

the absolute wind velocity and direction.

(All data collected with the ship stopped in

the water);

2. Measurement of temperature and specific

mass of sea water;

3. Fixing of measuring course against direc-

tion of seaway;

4. Navigating through the approach distance

on direct course;

5. Prepare all measurements to start (3 min. in

advance of measurement);

6. Start speed run. Control levers should re-

main unchanged, maximum rudder angle

shall not be more than 3 deg. port and star-

board. After agreed distance (2 to 3 nm) or

duration (10 minutes) stop speed run;

7. Weather observations (measurements of air

and sea water temperature, relative wind

speed and direction).

8. Turn ship with small rudder angles to navi-

gate the counter run at the same geographi-

cal location as the first run;

9. Repeat steps 5 to 8.

10. REPORTING

In the trial report an overview is given of

the trial conditions and results plus all correc-

tions necessary to arrive at the contractual

speed and the EEDI speed.

The trial report should contain all relevant

information to carry out all data analyses. It

should be written in such a way that all results

can be reprocessed.

The trial report should contain the follow-

ing sections

(i) Trial Report Summary this should

comprise details of

(aa)Ship particulars (including trial

draughts and displacement)

(ab) Propeller Details

(ac) Engine Data

(ad) Details of Appendages and Rudder

(ii) Contract conditions including contract

speed, power, and displacement.

(iii) EEDI conditions including EEDI speed,

power and displacement.

(iv) Description of Instrumentation this will

describe the instrument set-up, calibra-

tion procedure, Data Acquisition inter-

facing details, Location of sensors (e.g.

wind meter), etc.

(v) Description of Trial Site. This will give

information on geography, distance

from land, water depth, Air temperature,

Water temperature, water density etc.

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(vi) Environment Parameters this will list

out the measured/estimated environ-

mental conditions at site during trials

such as wave height, wave direction,

sea state, Air pressure, Wind direction,

Wind velocity etc.

(vii) Trial Agenda this will give a complete

and chronological order of the trial pro-

gramme (both planned and actual) with

specification of duties of different re-

cording/monitoring stations on board.

(viii) Trial Results

a) Date

b) Time

c) Run no

d) Ship position

e) Ship's heading

f) Run duration

g) Average ship speed

h) Average and standard deviation

torque (per shaft)

i) Average shaft rpm (per shaft)

j) Average shaft power (per shaft)

k) Average rudder angle

l) Relative wind speed and direction

m) Significant wave height and direc-

tion (sea state)

(ix) Analysis of Correction methods. The

analysis and correction of the measured

trial data should be conducted in com-

pliance with Part II of these Guidelines.

(x) Conclusions / Recommendations.

REFERENCES

[1] ITTC 7.5-04; “Recommended Procedures

and Guidelines for Speed/Power Trials”,

23rd

ITTC 2002.

[2] ISO 19019; “Guide for Planning, Carry-

ing out and Reporting Sea Trials”, 2002.

[3] ISO 15016; ”Guidelines for the assess-

ment of speed and power performance by

analysis of speed trial data”, 2002.

[4] Sea Trial Analysis JIP; “Recommended

Practice for Speed Trials”, 2006, Public

document from www.marin.nl.

[5] ITTC Recommendations and Guidelines

for Resistance & Propulsion Model Tests,

23rd

ITTC, 2002.

.

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APPENDIX I

General Ship and Trial Conditions Reported

Ship Hull

Draft

Trim Displacement and load

Hull appendages and Rudder

Geometry, deviation, roughness

Type

Rate of Movement

Propeller

Geometry, deviations, roughness

Pitch


Number of blades

Propeller(s)

Geometry, deviations, roughness

Pitch


Number of blades

Trial Site

Water depth

Water temperature

Air temperature

Sea State

Specific gravity of water

Environmental conditions

Wind

Waves

Current

Atmospheric pressure

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APPENDIX II

Beaufort Scale of Wind

This table is only intended as a guide to show roughly what may be expected in the open sea, remote from land. It should never be used in the reverse way; i.e., for logging or reporting the state of the sea. In enclosed waters, or when near land, with an off-shore wind, wave heights will be smaller and the waves steeper. Figures in brackets indicate the probable maximum height of waves

BE

AU

FO

RT

NU

MB

ER

DESCRIP-

TIVE

TERM

VELOCITY EQUIVALENT AT A STANDARD HEIGHT

OF 10 METRES ABOVE OPEN FLAT GROUND

SPECIFICATIONS

Probable

wave

height* in

metres

Probable

wave

height* in

feet Mean

velocity

in knots

m s_1 km h

_1

m.p.h.

Land

Sea

Coast

0

1

2

3

4

5

6

7

8

9

10

11

12

Calm

Light air

Light breeze

Gentle breeze

Moderate breeze

Fresh breeze

Strong breeze

Near gale

Gale

Strong gale

Storm

Violent storm

Hurricane

< 1

1–3

4–6

7–10

11–16

17–21

22–27

28–33

34–40

41–47

48–55

56–63

64 and over

0–0.2

0.3–1.5

1.6–3.3

3.4–5.4

5.5–7.9

8.0–10.7

10.8–13.8

13.9–17.1

17.2–20.7

20.8–24.4

24.5–28.4

28.5–32.6

32.7 and over

< 1

1–5

6–11

12–19

20–28

29–38

39–49

50–61

62–74

75–88

89–102

103–117

118 and over

< 1

1–3

4–7

8–12

13–18

19–24

25–31

32–38

39–46

47–54

55–63

64–72

73 and over

Calm; smoke rises vertically

Direction of wind shown by smoke drift but not by wind vanes

Wind felt on face; leaves rustle; ordi- nary vanes moved by wind

Leaves and small twigs in constant motion; wind ex- tends light flag

Raises dust and loose paper; small b ranches a re moved

Small trees in leaf beg in t o sway; crested wavelets form on inland waters

Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty

Whole trees in motion; inconvenience felt when walking against wind

Breaks twigs off trees; generally impedes progress

Slight structural damage occurs (chimney pots and slates removed)

Seldom experienced inland; trees uprooted; consider- able structural damage occurs

Very rarely experienced; accompa- nied by wide- spread damage

—

Sea like a mirror

Ripples with the appearance of scales are formed, but without foam crests

Small wavelets, still short but more pronounced; crests have a glassy appearance and do not break

Large wavelets; crests begin to break; foam of glassy appearance; perhaps scattered white horses

Small waves, becoming longer; fairly frequent white horses

Moderate waves, taking a more pronounced long form; many white horses are formed (chance of some spray)

Large waves begin to form; the white foam crests are more extensive everywhere (probably some spray)

Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind

Moderately high waves of greater length; edges of crests begin to break into the spindrift; the foam is blown in well-marked streaks along the direction of the wind

High waves; dense streaks of foam along the direction of the wind; crests of waves begin to topple, tumble and roll over; spray may affect visibility

Very high waves with long over- hanging crests; the resulting foam, in great patches, is blown in dense white streaks along the direction of the wind; on the whole, the surface of the sea takes on a white appearance; the tumbling of the sea becomes heavy and shock- like; visibility affected

Exceptionally high waves (small and medium-sized ships might be for a time lost to view behind the waves); the sea is completely covered with long white patches of foam lying along the direction of the wind; everywhere the edges of the wave crests are blown into froth; visibility affected

The air is filled with foam and spray; sea completely white with driving spray; visibility very seriously affected

Calm

Fishing smack just has steerage way

Wind fills the sails of smacks which then travel at about 1–2 knots

Smacks begin to careen and travel about 3–4 knots

Good working breeze, smacks carry all canvas with good list

Smacks shorten sail

Smacks have double reef in main- sail; care required when fishing

Smacks remain in harbour and those at sea lie to

All smacks make for harbour, if near

—

—

—

—

—

0.1 (0.1)

0.2 (0.3)

0.6 (1)

1 (1.5)

2 (2.5)

3 (4)

4 (5.5)

5.5 (7.5)

7 (10)

9

(12.5)

11.5 (16)

14 (—)

—

1/4

(1/4 )

1/2

(1)

2 (3)

31/2

(5)

6 (81/2)

91/2

(13)

131/2

(19)

18 (25)

23 (32)

29 (41)

37 (52)

45 (—)

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State of the sea

Code Descriptive terms

Height* figure in metres

0 Calm (glassy) 0

1 Calm (rippled) 0 – 0.1

2 Smooth (wavelets) 0.1 – 0.5

3 Slight 0.5 – 1.25

4 Moderate 1.25 – 2.5

5 Rough 2.5 – 4

6 Very rough 4 – 6

7 High 6 – 9

8 Very high 9 –14

9 Phenomenal Ove r 14

N o t e s:

(1) * These values refer to well-developed wind waves of the open sea. While priority shall be given to the de-

scriptive terms, these height values may be used for guidance by the observer when reporting the total

state of agitation of the sea resulting from various factors such as wind, swell, currents, angle between

swell and wind, etc.

(2) The exact bounding height shall be assigned for the lower code figure; e.g. a height of 4 m is coded as 5.

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APPENDIX III

Example Speed Trials Log Sheet

Ship name: Date:

Tfwd m Tair ⁰ C outer dia D1 mm

Taft m Twater ⁰ C inner dia D2 mm

Displacement tons ρwater kg/m3 steel type N/mm2

Run No. Time DescriptionForward /

Return runHeading Speed (SOG) Power Revs Speed Direction Height Direction Period UKC

[-] [-] [-] [F / R] [deg] [kn] [kW] [RPM] [kn] [m/s] [deg] [m] [deg] [s] [m]

Relative windPropeller Waves visual

Speed - Power Trials Log Form

Ship

m

Height of

anemometer

above water:

Environment Propeller shaft

ITTC Guidelines Conduct of S P Trials V0.5 ModHSVA

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