Berth 408 Marine Oil Terminal Passing
Vessel Dynamic Mooring Analysis
Prevention First 2008
September, 2008
Long Beach, CA
David Dykstra, Moffatt & Nichol
Why Conduct Passing Vessel Analysis for MOT?
Larger Vessels with deeper Drafts and
Confined Channels are Inducing
Greater Forces on Moored Vessels
Passing Vessel Analysis Required by
MOTEMS
MOTEMS Suggests PASSMOOR
Analytical Approach
Analytical Approach Based on Lab
Tests of Previous Generation Vessels
Limitations of MOTEMS Recommended Approach
Force factors based on limited number of
tests of specific ship hulls, passing
speeds/distances – cannot account for all
variations in ship type
Open water only – no harbor effects
(seiches, quay walls, etc)
Only parallel passing ships
Dynamic Mooring Analysis
Dynamic analysis is critical for assessing
effects of passing vessels
Mooring system acts as a spring, storing
energy
Due to the oscillating surge force during
passing events, stored energy and passing
forces act together to amplify mooring
response
These effects cannot be evaluated with
static mooring models
Passing Vessel Dynamic Mooring Analysis
Passing
Velocity +FX
+FY
Ship 2 (Moving)
Ship 1 (Moored)
+MZ
X/L
L
V
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
X/L
Fx
Fy
Mz (ft-kips)
DIM
EN
SIO
NL
ES
S A
PP
LIE
D F
OR
CE
& M
OM
EN
T
Berth 408 Passing Vessel Dynamic Mooring Analysis
Moored Vessel Characteristics
Item Unit Vessel
Vessel class - VLCC SUEZMAX
Vessel name - “Generic”
Design Vessel Asian Spirit
DWT Metric ton 325,000 152,000
Displacement Metric ton 370,000 174,000
LOA ft 1,135 883
LBP ft 1,070 846
Beam ft 197 150
Loaded draft ft 74 57
Ballast draft ft 33 27
Type of mooring lines - Wire Wire
Diameter of mooring lines in 1 5/8 1 1/2
Minimum breaking load Metric ton 114 94
Tail length ft 36 36
Diameter synthetic tail mm 100 76
Breaking strength of tail Metric ton 167 134
Pre-tension mooring lines ton 17 9
Winch brake holding capacity ton 68 75
Post-Panamax Emma Maersk Characteristics
Deadweight 157,000 mt
Design TEU 11,000
Length Overall 398 m
Length Between Perpendiculars 376 m
Beam 56.4 m
Hull Depth 30.2 m
Loaded (Design) Draft 15.5 m
Displacement 221,605 mt
Calculated
Forces on Moored Vessel
Time History
Dynamic
Mooring Loads and
Motions
Moored Vessel
Hydrodynamic
Coefficients and
Mooring Configuration
Dynamic
Mooring Model Time
Domain Simulation
DYNAMIC ANALYSIS METHODOLOGY
DELPASS Model
Developed by Prof. J.A. Pinkster of Delft
University in conjunction with Maritime
Research Institute of the Netherlands
(MARIN)
Panel Model based 3D Potential Theory
Panel models represent precise
representation of ship hulls, channels, and
walls
Allow computation of pressures and
velocities at any point on the hulls or
channels
DELPASS Features
Landfill side slopes included
Proximity of moored vessel toshoreline
Actual vessel shapesincorporated
Basin geometry accounted for
Bathymetry explicitly modeled
DELPASS Features
Complete vessel path in the vicinity of the moored vessel simulated
Free surface effectsincluded
-20
-15
-10
-5
0
5
10
0 500 1000 1500 2000 2500 3000
Time (sec)
WS
E (
cm
)
DELPASS features
Detailed harbor geometryNon-parallel vessels
Explicit panel models of hull forms
Computes Confined Channel Effects
Free Surface Effects
DELPASS Validation Laboratory Data Remery, 1974
Same data set original PASSMOOR used
DELPASS Validation (Pinkster, 2004) Full-Measurements,
Amsterdam 2003
Bulk Carrier passing barge berth
Panel Models for Moored VLCC and Passing Vessel
Moored Vessel and Passing Vessel Course
Main C
hannel
Pier 400
Reservation Point
Pier 300
Turning Basin
Main C
hannel
Pier 400
Reservation Point
Pier 300
Turning Basin
Forces on VLCC with 100 m Gap
Figure Error! No text of specified style in document.-1: Passing Forces on VLCC 100m
Gap: 4 knots (left) and 6 knots (right)
0 500 1000 1500 2000 2500Seconds
-150
-100
-50
0
50
100
150
Su
rge
Fo
rce
(m
t)
-200
-100
0
100
200
300
400
500
Sw
ay F
orc
e (
mt)
-15,000
-10,000
-5,000
0
5,000
10,000
15,000
Ya
w M
om
en
t (m
t -
m)
DELPASS
0 500 1000 1500 2000 2500Seconds
-150
-100
-50
0
50
100
150
Su
rge
Fo
rce
(m
t)
-200
-100
0
100
200
300
400
500
Sw
ay F
orc
e (
mt)
-15,000
-10,000
-5,000
0
5,000
10,000
15,000
Ya
w M
om
en
t (m
t -
m)
DELPASS
4 Knots 6 Knots
Dynamic Mooring Model
Time Domain- 6 Degrees of Freedom
Hydrodynamic Coefficients
Added mass/Damping Coefficients
Impulse-Response Functions, Constant Inertial Coefficient
Viscous damping terms
Models Wind, Wave, and Current
Nonlinear Mooring Restraints
Mooring lines, fenders, chains, etc.
Mooring Line Arrangement
Line Loads and Manifold Motions without Wind and Waves
Surge Sway Case Passing
Speed
(kts)
Gap
(m)
Maximum
Line Load
(mt)
Percent
SWL
Criteria?
Max
(m)
Min
(m)
Max
(m)
Min
(m)
Meets
Motion
Criteria?
1 4 100 22.7 36% 0.36 -0.27 0.03 -0.04 Yes
2 5 150 22.5 36% 0.36 -0.28 0.02 -0.04 Yes
3 6 200 21.7
35% 0.34 -0.22 0.00 -0.03 Yes
4 6 150 40.3 64% 0.85 -0.48 0.15 -0.06 Yes
5 6 100 87.6 140% 1.50 -0.82 0.78 -0.19 Yes
Suezmax 6 150 15.0 29% 0.17 -0.19 -0.01 -0.03 Yes
Line Loads and Manifold Motions with Wind and Waves
Surge Sway Case Passing
Speed
(kts)
Gap
(m)
Maximum
Line Load
(mt)
Percent
SWL
Criteria?
Max
(m)
Min
(m)
Max
(m)
Min
(m)
Meets
Motion
Criteria?
1 4 100 26.9 43% 0.48 -0.33 0.23 -0.07 Yes
2 5 150 25.1 40% 0.45 -0.32 0.16 -0.07 Yes
3 6 200 24.5
39% 0.45 -0.32 0.11 -0.06 Yes
5 6 150 47.1 75% 0.97 -0.53 0.39 -0.11 Yes
5 6 100 94.7 151% 1.57 -0.87 0.98 -0.20 Yes
Suezmax 6 150 31.5 61% 0.38 -0.34 0.39 -0.10 Yes
Results for Case 6 kt and 150 m Separation without
Wind or WavesMaximum Mooring Line Loads, No Wind, No Waves
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0
20
40
60
80
100
120
140
160
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Mooring Line Number
Ma
x L
ine
Te
ns
ion
(m
t)
SWL
MBL
Manifold Motion
-0.5
0
0.5
1
1.5
2
-3 -2 -1 0 1 2 3
Surge (meters)
Sw
ay
(m
ete
rs)
Manifold Track
Start/End
Figure Error! No text of specified style in document.-1: Case 4 VLCC Mooring Line
Loads (top) and Manifold Motions (bottom)
Results for Case 6 kt and 100 m Separation without
Wind or WavesMaximum Mooring Line Loads, No Wind, No Waves
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0
20
40
60
80
100
120
140
160
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Mooring Line Number
Ma
x L
ine
Te
ns
ion
(m
t)
SWL
MBL
Manifold Motion
-0.5
0
0.5
1
1.5
2
-3 -2 -1 0 1 2 3
Surge (meters)
Sw
ay
(m
ete
rs)
Manifold Track
Start/End
Effects of Wind and Waves
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0
20
40
60
80
100
120
140
160
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Line Number
Lin
e T
en
sio
n (
mt)
Passing Ship Only
Passing Ship w/ Waves
Passing Ship w/ Wind
Passing Ship w/ Wind + Waves
SWL
MBL
Summary and Conclusions
Dynamic analysis of moorings is an essential
tool for port designers
Threatening loads – in excess of computed
stationary loads – may be experienced for high
passing speeds and narrow separations.
Simplified MOTEMS approach may not produce
accurate forces.
Vessel speeds may need to be reduced or
separation distances increased where potential
problems exist
Berth 408 Marine Oil Terminal
Passing Vessel Analysis
David Dykstra, Moffatt & Nichol
Thank You!