MEPC.1/Circ.901
24 June 2022
GUIDANCE ON METHODS, PROCEDURES AND VERIFICATION OF IN-SERVICE
PERFORMANCE MEASUREMENTS
1 The Marine
Environment Protection Committee, at its seventy-eighth session (6 to 10 June
2022), approved the Guidance on methods, procedures and verification of
in-service performance measurements for the purpose of the EEXI
calculation, as set out in the annex.
2 Member Governments
are invited to bring the annexed Guidance to the attention of their
Administrations, industry, relevant shipping organizations, shipping companies
and other stakeholders concerned.
ANNEX
GUIDANCE ON METHODS, PROCEDURES AND VERIFICATION OF IN-SERVICE
PERFORMANCE MEASUREMENTS
CONTENTS
1 INTRODUCTION
2 OVERVIEW
3 PREPARATIONS
4 DURING THE
IN-SERVICE PERFORMANCE MEASUREMENTS
5 AFTER THE
IN-SERVICE PERFORMANCE MEASUREMENTS
APPENDIX A - INFORMATION TO
BE SUBMITTED PRIOR TO CONDUCTING THE INSERVICE PERFORMANCE MEASUREMENTS.
APPENDIX B - INFORMATION TO
BE SUBMITTED FOR VERIFICATION AFTER THE INSERVICE PERFORMANCE MEASUREMENTS.
APPENDIX C - EXAMPLE OF THE
IN-SERVICE PERFORMANCE MEASUREMENTS REPORTING FORM
1 Introduction
In cases where the speed-power curve is not available or the sea
trial report does not contain the EEDI or design load draught condition, the
ship speed Vref can be obtained from the inservice performance
measurement method for the purpose of the EEXI calculation, in accordance with
paragraph 2.2.3.5 of the EEXI Calculation Guidelines, as set out in resolution MEPC.350(78).
2 Overview
2.1 When carrying out
the in-service performance measurements, common international standards1
should be referred to, unless explicitly specified in this guidance.
________________
1 Such as ITTC quality
procedures, ISO 15016:2002, ISO 15016:2015 and/or ISO 19030:2016.
2.2 An overview of
preparations and procedures are outlined in the table below. The preparations
and the processes should be discussed and agreed at the pre-meeting, see
section "Preparations.
Table 1: In-service performance sea trial preparations and
procedures
|
In-service
performance measurement analysis |
|
|
Step
1: Preparing sensors |
Speed log / GPS Echosounder Heading control Fuel flow meter Shaft torsion meter Draft measurement Gyro compass |
|
Step
2: Pre-trial parameters |
Displacement Forward/Aft draughts Water depth Air/Sea temperature Seawater density Anemometer height Fuel density Fuel LCV |
|
Step
3: In-service performance measurement |
Sea state Wind Water depth Currents |
|
Step
4: During trial parameters |
Reported data System prints Equipment control Fuel analysis |
|
Step
5: Documentation |
Shaft RPM/Power Heading Ship's speed Distance
Wind speed/direction Current speed/direction Wave height/period/direction |
2.3 When using the
in-service performance measurement method, a meeting should be arranged between
all stakeholders involved in the process: the owner, the possible consultant,
the verifier and the authority before conducting the in-service performance
measurements. An overview of the available information including but not
limited to ship design, energy saving devices (ESD) and measurement sensors
should be included. The plan for the period of the in-service performance
measurements should be agreed upon and expectations regarding the delivery of
the analysis and its format should be aligned.
3 Preparations
3.1 One of the most
important aspects of a successful in-service performance measurement procedure
is the preparation. Relevant instruments should be calibrated and their
operational conditions prior to the commencement of the trials should be
confirmed by the verifier.2 The list below indicates the primary
instruments to be used for collecting the data:
_________________
2 The Verifier is the flag
Administration, or a competent organization delegated by the flag
Administration.
Table 2: Sensors for In-service performance trials
|
Sensor |
Remarks |
|
Shaft torque meter |
The measurement system should be certified for power
measurements with a bias error as small as practicable. Zero setting checked
before and after test. |
|
GPS |
The GPS system should operate in the differential mode to ensure
sufficient accuracy. |
|
Anemometer |
It should be clear of possible obstructions (superstructure,
masts, funnel, etc.) and its height from sea level recorded. |
|
Draft measurements |
Draft measurement system (if available and calibrated):
Otherwise, physical observation is required. |
|
Speed log |
The sensor should have been cleaned recently. |
|
Echo sounder |
Important for checking water depth for safety and ensuring there
are no effects from shallow water on the ship performance. |
|
Course recorder |
Should be checked before the trial and be able to provide a
course printout following each trial run. |
|
Fuel flow meter |
Either volume flow or mass flow meters to be fitted to ships.
Both should be calibrated and cleaned/maintained as per manufacturers
recommendations. |
|
Gyro compass |
Record the ship's heading during the voyage and should be
calibrated prior to the trials. |
3.2 The ship should be
equipped with a calibrated shaft torque meter, at least for the complete
duration of the in-service performance measurement. For verification and cross
checks, the detailed fuel properties information, the logged engine room
conditions and the fuel oil consumption details will give an estimate of the
power used at a certain fuel oil consumption value.
3.3 If an automated
data acquisition system is installed on board, this should be checked for
accuracy prior to the performance measurements, to ensure that the system has
the required precision and measurement frequency, that can provide a trace of
all the data required.
3.4 Before the start of
each performance measurement run, the following should be noted in the data
logging template form (example appendix C):
Table 3: In-service environment and conditions
|
Parameter |
Remarks |
|
Displacement |
Speed trials should be performed at displacement and draught
conditions, which are comparable to those of the delivery sea trials or model
tests or assumed ballast conditions. The trim shall be maintained within very
narrow limits. For the even keel condition, the trim shall be less than
0.1 % of the length between perpendiculars. For the trimmed trial
condition, the fore draught shall be within 0.1 m of the ship's
ideal condition. |
|
Draught forward, mid and aft |
|
|
Water depth |
No remarks |
|
Air temperature |
Air temperature and pressure should be measured using a
calibrated thermometer and barometer. |
|
Air pressure |
|
|
Sea water temperature |
The local seawater temperature and density at the trial site
should be recorded to enable the calculation of the ship's displacement and
corrections with regards to viscosity. The water temperature should be taken
at the waterline level. |
|
Sea water density |
|
|
Anemometer height |
Its height from sea level should be recorded. |
|
Fuel density |
The fuel's density and LCV to be obtained from a laboratorys
analysis report. |
|
Fuel LCV |
3.5 The in-service
performance measurements should be performed at the EEXI draught condition, and
if data exists for a reference condition, then a set of in-service performance
measurements may also be performed at this condition in order to better
calibrate the speedpower relation.
.1 The reference condition is the
condition for which the ship documentation exists, e.g. a sea trial curve in
ballast or a sea trial/model test curve in design conditions. The in-service
performance measurement result may be calibrated towards the reference
condition curve. The use of a reference condition, if available, should not
lead to overestimation of the Vref but can be a useful tool to
verify and calibrate the speed-power relation. If a reference condition is
used, this calibration result may also be used for the EEXI draught condition.
.2 The EEXI draught condition is the
draught condition as provided by paragraph 2.2.2 of the 2018 Guidelines on
the method of calculation of the attained EEDI for new ships (resolution MEPC.308(73), as
amended, the "EEDI Calculation Guidelines" hereafter). The
performance measurements results are used with the same calibration factor as
at the reference condition if available.
3.6 In case the exact
EEXI draught condition cannot be met, the Admiralty Coefficient formula may be
accepted to adjust the speed-power relation, only for displacement variations
of up to 2%, or to the satisfaction of the verifier.
3.7 The ship should
perform at least one set of in-service performance measurements for the EEXI
draught condition, and at power settings equivalent to the EEDI trial
conditions (set out in MEPC.1/Circ.855/Rev.2,
as amended). If that is not possible, then at each of the following power
settings of 30%, 60%, 75% and 90% of MCR, with a margin of +/- 5%. If data for
a reference condition is available, another set of in-service performance
measurements should also be carried out at this condition for calibration
purposes.
3.8 In case where an
overridable Shaft/Engine Power Limitation is installed, the power settings of
30%, 60%, 83% and 90% of the limited power may be used, with a margin of +/- 5%
for both sets of in-service performance measurements, to the satisfaction of
the verifier.
3.9 If the in-service
performance measurements are performed at consecutive power settings,
sufficient time in between change of settings should be considered, to be sure
that steady state conditions are obtained.
3.10 The duration of each
run should be performed according to table 4.
3.11 Prior to the
in-service performance measurements, the weather forecast should be studied to
ensure that favourable weather conditions will prevail during the trials (close
to calm conditions).
3.12 Crew members
involved in the execution should be familiar with the performance measurements
and be aware of their tasks and the importance of the measurements collected.
3.13 Safety of the ship
is paramount, and the performance measurements should be suspended should any
risks to the ship and/or crew be detected. All rules and regulations, as well
as good seamanship, are to be followed at all times.
3.14 The conditions and
plans specified in this section should be examined and confirmed by the
verifier prior to the in-service performance measurements.
3.15 The ship may
experience fouling of the hull and the propeller, which may influence the
performance of the ship. If the ship is heavily fouled during the in-service
performance measurements, the Vref attained may be less than
expected and this will lead to a penalty in the attained EEXI. It is
recommended to carry out in-service performance measurements when the ship has
a clean hull and propeller.
3.16 The ship may have
installed ESDs post delivery. This will affect the performance and the
in-service measurement may be used to reflect the effect of ESDs, as provided
in paragraph 2.2.3.7 of the EEXI Calculation Guidelines.
4 During the
in-service performance measurements
4.1 Once the in-service
performance measurements have begun, variations should be minimized, as the
accuracy of the ship performance measurements can be influenced greatly by
fluctuations in the parameters. Thus, all control levers should remain
unchanged.
4.2 An experienced
helmsman or adaptive autopilot will be required to maintain heading during each
run. Minimum rudder angles are to be used while maintaining a steady heading.
The helm corrections should be limited to five (5) degrees or less.
4.3 The following
conditions should be met, in order to reduce the influence of corrections and
obtain the best possible accuracy of the results of the performance
measurements:
Table 4: Environmental conditions for in-service performance
measurements
|
Parameter |
Remarks |
|
Sea state |
Conditions as specified in ISO 15016: 2015 |
|
Wind speed |
Conditions as specified in ISO 15016: 2015 |
|
Water depth |
Conditions as specified in ISO 15016: 2015 |
|
Currents |
Avoid
areas with known high current values and variations. During the trials, the
following condition should be met: VGPS - VSTW
< 0.3 knots, or
conditions as specified in ISO 15016: 2015 |
|
Trials period |
Trials
should be conducted in daylight |
|
Duration |
The
run duration should be the same for all speed runs with a minimum of 10
minutes, see figure 1 below |
4.4 If any of above
conditions are no longer met during in-service performance measurements, it
should be necessary to abandon the run.
4.5 Each set of the in-service performance measurements in the
respective load condition should be executed as at least one set of double
runs. It is important that the ship is running on the same track and when the
monitoring begins, the conditions are in steady state conditions. Each speed
run should be commenced and completed at the same place.
Figure 1: Sea trials with double runs
4.6 During the
in-service performance measurements, accurate recordings of the required
parameters are of great importance. Recording of parameters for each run should
start when steady state ship conditions are met.
4.7 The following data
should be collected at the beginning and end of each performance measurement
run:
|
Main engine supply flowmeter reading |
[ltr/h] or [kg/h] |
|
Main engine supply flowmeter temperature |
[deg] |
|
Main engine return line flowmeter reading* |
[ltr/h] or [kg/h] |
|
Main engine return line flowmeter temperature* |
[deg] |
(* For ships fitted with flowmeter on return line)
4.8 The following data
should be collected with a sampling rate of at least 1 Hz during the in-service
performance measurement:
Table 5: Logged parameters during in-service performance
measurements
|
Parameter |
Unit |
|
Date |
dd-mm-yyyy |
|
Time |
hh:mm:ss |
|
Revolution counter reading |
[s-1] |
|
Shaft power |
[kW] |
|
Heading |
[deg] |
|
Ship's speed (GPS and Speed Log) |
[knots] |
|
Distance ("0" should be at the beginning of each run) |
[nm] |
|
Relative wind speed |
[m/s] |
|
Relative wind direction (coming from) |
[deg] |
|
Current speed |
[knots] |
|
Relative current direction (going to) |
[deg] |
|
Observed wave height |
[m] |
|
Observed wave period |
[s] |
|
Observed wave direction (going to) |
[deg] |
4.9 Apart from power,
rpm and consumption, average prevailing values for the following main engine
parameters should be provided for each run for the following:
|
Scavenge air temperature |
[deg] |
|
Scavenge air pressure |
[kg/cm2] |
|
Blower air inlet temperature |
[deg] |
4.10 These, as well as
any other main engine data should be collected at local sensors' display and
not their repeaters inside the ECR.
4.11 As far as
practicable, the in-service performance measurement should be witnessed by the
verifier. The verifier should be able to confirm that the in-service
performance measurement was conducted in accordance with the agreed procedures.
5 After the
in-service performance measurements
5.1 All information
collected should be checked by the verifier and any errors/typos should be
noted in supplementary documentation, including any corrected/replaced values
clearly marked in the form. Data which is continually recorded should be
provided "as is" and non-variable data should be noted at the
beginning and the end of the in-service performance measurements in order to
confirm that any changes are set to a minimum.
5.2 For each run the
following should be submitted:
.1 one filled-in soft copy of the
"In-service performance monitoring reporting form" (appendix C);
.2 printouts and/or soft copies from the
performance monitoring system output;
.3 printouts and/or soft copies from the
loading computer calculations representing the loading condition at which the
run took place; and
.4 printouts and/or soft copies from the
course recorder for the period covering the run.
5.3 Also, a copy of the
fuel oil analysis for the fuel used during the in-service performance
measurements should be submitted.
5.4 Any comments about
the in-service performance measurements, including any large variations in
environmental conditions, should be noted.
5.5 A summary of the
required information to be submitted for verification can be found in appendix
A, B, and C.
APPENDIX A
INFORMATION TO BE SUBMITTED PRIOR TO CONDUCTING THE IN-SERVICE
PERFORMANCE MEASUREMENTS
The following information should be submitted prior to conducting
the performance measurements.
Ships main particulars
|
IMO
number: |
|
|
Date
delivered: |
|
|
Ship's
email address(s): |
|
|
Date
ship was launched (when did ship enter the water): |
|
|
Ship's
name: |
|
|
Owner:
|
|
|
Managing
company: |
|
|
Ship
type: |
|
|
Ship
capacity |
|
|
Yard:
|
|
|
Length
overall (m): |
|
|
Length
between perpendiculars (m): |
|
|
Breadth
moulded (m): |
|
|
Depth
to upper deck (m): |
|
|
Design
draft (m): |
|
|
Design
displacement (mt): |
|
|
EEXI
draft (m): |
|
|
Displacement
at EEXI draft (mt) |
|
|
Lightship
weight (mt) |
|
|
Design
speed (knots): |
|
|
Dry-docking history (within the last five years): |
|||
|
Date |
Yard |
Coating specs |
Hull treatment |
|
|
|
Please attach |
Please attach |
|
Hull cleaning and propeller polishing history since last
dry-dock: |
|||
|
Date |
Place |
Brief description of works |
Propeller polishing standard* |
|
|
|
|
|
* only for propeller
polishing events
|
Main engine(s) |
|
|
Maker: |
|
|
Type: |
|
|
Number: |
|
|
Type of fuel: |
|
|
MCR (kW): |
|
|
SMCR (kW) x RPM: |
|