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!

ddykstra@moffattnichol.com