1. No category

9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
1
IMO/MEPC assigned to the 27th ITTC the task of revising
ISO 15016:2002 to incorporate assessment of EEDI of a new
building. IMO asked for a transparent, un-ambiguous and
practical method acceptable for all stakeholders as well as
for the assessment of the IMO EEDI.
ITTC formed the ad hoc Specialist Committee on the
Performance of Ships at Sea (PSS) and assigned to it the
task to devise new procedure for:
27th ITTC PSS Committee produced two procedures for Speed
and Power Trials:
 , Part I Preparation and Conduct
 Part II Analysis of Speed/Power Trial Data
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
2
63rd IMO/MEPC adopted four sets of Guidelines to support
the implementation of the mandatory Regulations on
Energy Efficiency for Ships in MARPOL Annex VI, entered
into force on 1 January 2013:
1. On the calculation method of attained Energy
Efficiency Design Index (EEDI) for new ships (2002);
2. On the development of a Ship Energy Efficiency
Management Plan (SEEMP) (2012);
3. On on survey and certification of the Energy Efficiency
Design Index (EEDI) (2012); and
4. On the calculation of reference lines for use with the
Energy Efficiency Design Index (EEDI).
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
3
EEDI = CFME*(SFCME*PME+SFCAE*PAE)/(Capacity*VREF)
Where: CFME - Carbon emission factor
SFCME - Specific fuel consumption of main engine
SFCAE - Specific fuel consumption of auxiliary engines
PME - 75% of rated installed power (MCR) for each ME w/o any deduction
for shaft generators
PAE - Installed auxiliary power
Capacity – For dry cargo carriers, tankers, gas tankers,
containerships, ro-ro cargo and general cargo ships,
deadweight should be used instead(tons).
VREF – Ship speed (kn) in deep water for max design load
condition (capacity) as defined above, at the main engine
shaft power at 75%MCR, assuming calm weather (no wind
& no waves).
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
4
EEDI(details)
installed power for each
main engine (j)
required auxiliary
engine power
waste heat recovery
system
the main engine power
reduction due to
innovative energy
efficient technology
neff
nPTI


 M
  nME


 M

  f j    C FME ( i ) SFC ME ( i ) PME ( i )   PAE C FAE SFC AE
C FAE SFC AE 

f
P

f
P





j
PTI
(
i
)
eff
(
i
)
AEeff
(
i
)






i 1
i 1

 j 1   i 1
 j 1



EEDI 
f i Capacity　Vref f w
Capacity:
For cargo carriers, tankers, gas tankers,
container ships, ro-ro cargo and
passenger ships and general cargo ships,
>deadweight
•For passenger ships,
>gross tonnage
9/10/2014
Vref (ship speed)
measured in nautical miles per hour (knot),
on deep water in the maximum design load
condition (Capacity) at the output of the
engine(s) and assuming the weather is calm
with no wind and no waves.
 neff

  f eff ( i ) Peff ( i )C FME SFC ME 
 i 1

fW is a non-dimensional coefficient
indicating the decrease of speed in
representative sea conditions of wave
height, wave frequency and wind speed
(e.g., Beaufort Scale 6),
(fw=1 at this moment)
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
5
EEDI Application
Reduction of EEDI
Ship types for EEDI
calculation*
After 1st
January
2013
All new ships (according below table)
of 400GT and above, build from 1st
January 2013
Bulk carrier
X
Gas carrier
X
*
Tanker
X
Container ship
X
Reefer
X
Combination carrier
X
not apply to ships of diesel-electric
propulsion, turbine propulsion
and hybrid propulsion system
** separate to Gas carrier and LNG
carrier
*** only regulated for Passenger ship
having non-conventional
propulsion
9/10/2014
Passenger ship
After 1st
September
2015
**
X***
RO-RO cargo ship
X
RO-RO passenger ship
X
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
6
IMO Stipulated EEDI Reduction Rate
Phase
#
Vessel
built
EEDI
below
base
line
Phase 0
Jan 2013–
Dec 2014
0%
Phase 1
Jan 2015–
Dec 2019
10%
Phase 2
Jan 2020–
Dec 2024
20%
Phase 3
Jan 2025 –>
30%
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
7
EEDI Survey and Certification
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
8
Practical Aspects of EEDI Prediction
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
9
POWER CURVES
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
10
POWER CURVES ESTIMATION
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
11
Conclusions on EEDI Verification Process
 EEDI prediction process shall follow the Industry
guidelines
 Model tests shall be conducted according to ITTC
Recommended Procedures
 In EEDI regulation, model basins are requested to build a
quality control system, such as ISO-9000 or equivalent
 Trials are carried out at ballast condition while EEDI
refers to the full load (design) condition. Extrapolation is
carried out using the same thrust identity or correlation
coefficient method of 1978 ITTC. Studies showed that CP
and δΔCFC vary significantly with displacement. Further
studies on δCP/δΔCFC are necessary.
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
12
Preparation and Conduct
Purpose:
To determine ship performance in terms of speed, power and
propeller revolutions under prescribed ship conditions, and
subsequently:
 Verify the satisfactory attainment of the contractually
stipulated Ship Speed
 Provide the Ship Speed for the calculation of the Energy
Efficiency Design Index (EEDI) as required by IMO.
To derive the speed/power performance of the vessel from
the measured speed over ground, shaft torque and rpm, the
Direct Power Method is recommended
.
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
13
Preparation and Conduct
Part I is to define and specify:
 Responsibility of each party involved,
 Trial preparations,
 Vessel and propeller conditions,
 Limiting weather (wind) and sea conditions,
 Trial procedure,
 Execution of the trial,
 Measurements required,
 Data acquisition and recording
 Processing of the results.
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
14
Trial Preparations
Hull surface roughness and fouling – Clean &
smooth hull
Propeller roughness and fouling – clean &
smooth (polished) propeller
Draughts - averaging the ship draft mark
readings => by draft marks and/or draft
gauging system
Trim < 1.0% Tm; Optimum trim do not
considered (varies with speed)
Displacement - within +/-2% difference from
the actual required displacement
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
15
Wind and Wave Measurements
Relative Wind – Speed and direction
• Correction for superstructure
• Correction for height > 10 m above sea level
Waves – Hs/Tp and direction
• Visual observation (min 3 observers)
• Wave buoy
• Wave radar
Current – speed and direction
• ”Mean-of-means” of vessel speed during two consecutive double
runscurrent speed varies parabolically over time
• ‘’Iterative method” (assumes to vary with a semidiurnal period
P(Vs)=a+bVs^q
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
16
Wind/Wave Limits
Limiting weather (wind) and sea conditions:


9/10/2014
Wind speed should not be higher than:
Beaufort number 6, for vessels with L >100 m
Beaufort number 5, for vessel with ≤100 m
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
17
Preparation and Conduct
Ship track during double run:




9/10/2014
These runs comprise:
Two (2) Double runs (at the same
power setting) around the
Contract Power,
Two (2) Double runs (at the same
power setting) around EEDI
Power (i.e. 75% MCR),
Two (2) Double Runs for at least
one other power setting between
65% and 100% MCR.
Logging duration minimum 10
min for all runs
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
18
Preparation and Conduct
Data Acquisition and Recording:










9/10/2014
Time
Propeller shaft torque
Propeller shaft rpm
Pitch of CPP
Ship positional data
Ship heading
Ship’s speed over ground
Relative wind direction
Relative wind speed
Wave height, period and direction
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
19
Analysis
Main Objectives of Part II:
 To define procedure for the evaluation and
correction of speed/power trials covering:
 Wind correction
 Waves correction
 Current correction
 Temperature and salinity correction
 Shallow water effect correction
 Displacement correction
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
20
Analysis
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
21
Analysis
Direct power method is applied, combined with test
results from load variation tests.
with
PSC:
PSM:
VS:
ΔP:
ΔR:
ηD:
9/10/2014
corrected power,
measured power,
ship speed through the water,
required correction for power,
resistance increase,
propulsion efficiency coefficient.
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
22
Analysis
The resistance values of each run are corrected by estimating the
resistance increase ΔR as,
with
RAA :
RAS :
RAW :
9/10/2014
resistance increase due to relative wind,
resistance increase due to deviation of water
temperature and water density,
resistance increase due to waves,
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
23
Correction for Propeller Loading
The load variation
propulsion test
has been selected
to account for the
influence of
propeller loading
on the propulsive
efficiency
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
24
Correction - Wind
Validation summary, based on NMRI wind
tunnel data-base
Validation indicated smallest
error for Fujiwara 2005 method
SEEST
0.5
Fujiwara2005
Yamano
Fujiwara1998
Yoneta
Isherwood
STA
As a result of the
validation, the following
three possible approaches
were recommended:
 (1) Statistical regression
formula for various ship
types developed by Fujiwara
0.4
0.3
 (2) STA Dataset
0.2
 (3) Use of wind tunnel
0.1
measurements for the
specific ship
0.0
CAA
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
25
Analysis
Wave Added Resistance
 Short waves (λ/L < 0.25):
 No pitch/heave motions
 Wave added resistance
dominated by wave reflection
only
 Long waves (1 > λ/L < 0.25):
 Pitch/heave motions
 Wave added resistance
governed by both wave
reflection and wave radiation
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
26
Wave added resistance
Wave added resistance calculation approaches:
 Simplified approach for ships which do not heave and pitch (STA1)
 Empirical approach with frequency response function for ships which
heave and pitch (STA2 method); note requires measured wave
spectrum!!!
 Theoretical approach combined with simplified tank tests
(ΔR calculated based on Maruo’s theory valid for short waves,
hence this approach is valid only for benign conditions)
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
27
Correction - Waves
Three methods validated:
RAW prediction (kN)
STAWAVE1
800
HSVA tank tests
700
500

added resistance
due to reflection
2
a
NMRI tank tests
600
motion induced
added resistance
ra w
MARIN tank tests
400
300
200
2
1
1/2
1/4
1/8
 / Lpp 
 STAWAVE1 – accounts only for
wave reflection only
 STAWAVE2 – empirical
correction method with
frequency response function
100
RAW prediction (kN)
STAWAVE2
800
0
0
100
200
300
400
HSVA tank tests
MARIN tank tests
NMRI tank tests
SSPA tank tests
500
600 700 800
700
R AW experiment (kN)
600
500
400
300
 NMRI – theoretical method
with empirical corrections.
Provides the added resistance
RAO
9/10/2014
200
100
0
0
100
200
300
400
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
500 600 700 800
RAW experiment (kN)
28
Current Correction
“Means-of-means” method requires
minimum two double runs in case of
quadratic current variation.
Specifics:
Assumes that current (tidal) varies periodically
with time.
 Within the time frame of a double run, the
current is assumed to vary parabolically
with time.
 In case of a single run, the current is
assumed constant (time-independent).
2 double runs
take 8 hours
Tidal period is
about 12 hours
Inflection point exists
during the trials
Special case => large low speed ships (VLCC),
one run up to 2 hrs.
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
29
Current Correction
Iterative method assumes following current variation with semidiunal period
 2
VC  VC,C cos
 TC

 2
t   VC,S sin 

 TC

t   VC,T t  VC,0

where:
VC : is the current speed in knots,
TC : is the period of variation of current speed,
t : is the time for each run.
and unknown factors VC,C, VC,S, VC,T and VC,0.
First approximation of Speed Through Water (STW)
PVS   a  bVSq
Where in each step:
9/10/2014
VS  VG  VC
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
30
Current Correction
Flow chart of the iterative method:
VS , Pid , t
V 'G , P'id
PVS   a  bVSq
Converged?
2
 PVSi  Pidi 
DPM
VS  VG  VC
VS  q
pa
b
VC  VG  VS
 2 
 2 
VC  VC,C cos t   VC,S sin  t   VC,Tt  VC,0
 TC 
 TC 
Refer to Clause 12. k).
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
31
Sea Trial to EEDI Condition Correlation
Requirements and Technical
challenges:
 Difference of the model-ship
correlation between fully loaded
(EEDI) condition and trial (ballast)
condition
 1978ITTC Performance Prediction
Method (PPM) shall be used
 Correlation based on thrust
identity and correlation factors to be
according method 1 (Cp-Cn) or
method 2 (ΔCFC-ΔwC) of the ITTC
PPM
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
32
PSS Study on CP and ΔCFC, source:
Shipbuilding Research Center of Japan (SRC)
Variation of δCP as a function of the displacement ratio
Variation of ΔCFC as a function of the displacement ratio
Note: Values are provided by Clients and NOT confirmed
by sea trial data!
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
33
Impact on Model Tests and Speed Trials
 Load variation tests should be part of the calm water propulsion
model test program and the analysis of these tests should be
according to the described procedure.
 For extrapolation to full scale the same procedure and empirical
coefficients should be used for all draughts unless these
procedures and coefficients are justified and documented with
results of full scale trials for the specific ship type, size and
loading condition.
 Speed trial shall consist of 5 double runs with minimum 10
minutes for the first ship, though for sister ships the programme
can be reduced to 3 double runs.
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
34
Recommendation for Future Work:
Refinement of the recommended procedures:
 Temperature and density correction to take into account temp/density
gradient

Investigate statistical results from load variation tests

Investigate new shallow water method to replace Lackenby

Investigate wave limits for the wave correction methods

Investigate application of CFD methods for wind loads

Expand the wind coefficient database for more ship types

More extensive validation of the wave correction methods (STA1, STA2, NMRI)

Investigate feedback of speed/power data for correlation purpose especially for
the design and EEDI draft
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
35
Recommendation for Future Work:
Explore “Ship in Service” issues
 f w application of tools investigated by the seakeeping committee
 Investigate feedback of speed/power data for f w
 Investigate the monitoring and analysis of speed/power performance of
ships in service
 Investigate EEOI issues originating from IMO requirements
 Investigate the influence of ship hull surface degradation due to fouling
and aging on the speed/power performance
Develop procedures how model tests with Energy Saving Devices such as ducts,
pre-swirl fins, hub vanes, hull vanes, rudder fins and unconventional
propellers should be conducted and how the measured results should be
extrapolated to full scale; this suggestion is more applicable for the
Propulsion committee
ITTC to develop guidelines for the model testing community how to deal with the
EEDI verifiers: what are they allowed to see; what documents to deliver to
them; how to secure data confidentiality of our direct customers, etc.
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
36
QA session
 Questions & Answers
9/10/2014
TECHNICAL MEETING OF THE GREEK SECTION OF SNAME
37