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Mooring Loads Analysis

The hull of the Karish FPSO is moored in COSCO Zhoushan shipyard and is expecting a typhoon on October 1st. The document analyzes the vessel's wind load and mooring arrangement. It calculates the transverse and longitudinal windage areas using the vessel's dimensions. It then uses these areas and wind speed data to calculate the transverse and longitudinal wind loads for wind speeds of 27 m/s and 40 m/s. Finally, it models the mooring rope loads and safety factors for winds from the south and east, finding safety factors above criteria for all ropes at 27 m/s winds but below criteria for some ropes at 40 m/s winds. COSCO submitted a revised mooring plan

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WK
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433 views1 page

Mooring Loads Analysis

The hull of the Karish FPSO is moored in COSCO Zhoushan shipyard and is expecting a typhoon on October 1st. The document analyzes the vessel's wind load and mooring arrangement. It calculates the transverse and longitudinal windage areas using the vessel's dimensions. It then uses these areas and wind speed data to calculate the transverse and longitudinal wind loads for wind speeds of 27 m/s and 40 m/s. Finally, it models the mooring rope loads and safety factors for winds from the south and east, finding safety factors above criteria for all ropes at 27 m/s winds but below criteria for some ropes at 40 m/s winds. COSCO submitted a revised mooring plan

Uploaded by

WK
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as XLSX, PDF, TXT or read online on Scribd
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Karish FPSO hull - mooring arrangement analyis Date: 30/09/2019

The hull is moored in COSCO Zhoushan shipyard The expected typhoon on 1st of October

Vessel transvers windage area:


B 50.0 m
H 27.0 m
Structure above Main Deck 5.0 m
Draft min 3.3 m
FB 28.7 m H+S-Dm
AT 1435.0 m2 B*FB

Vessel longitudinal windage area


L 227.0 m
H 27.0 m
Tf 3.3 m
Ta 3.8 m
Tm 3.6 m (Tf +Ta)/2
Structure above Main Deck 5.0 m
WL to Quayside dist 6.0 m
h 22.5 m H+S-Ta-WLiiQ
AL 5096 m2 L*h

Wind load

Formula: F =0.5* r*V2*A*Cd


r 0.995 N/m3

V - wind speed (Windy.com) V 27 m/sec


V - wind speed (JTWC) V 40 m/sec
Cd - drag coeficient 2
(Cd for flat rectangular surface perpend to the wind direction)

for 27 m/sec for 40 m/sec


[kN] [kN]
FT 1,041 2,285
FL 3,697 8,113

Due to no accommodation/superstructure and rectangle hull


assume FL distibuted 50/50 between Fwd and Aft mooring set

FL/2 1,848 4,057

Revised mooring pland submitted by COSCO 30th of October 2019

Mooring ropes reaction loads


Assumptions:
Two worse case scenarios are taken in to account only
Wind from direction S
Wind from direction E
All mooring ropes are divided in to 3 groups (Forward, Aft, Astern)
For each group the load distribution factor was assumed 1/1.3 = 0.77 0.77
For all ropes the rope angle (cosinus 45 deg) factor was assumed 0.7 (no other factors for individual different angles) 0.7
To copmensate for the different stretch between Nylon and Dynema additional load contribution factor for Nylon ropes was assumed 0.3

formula:

Dynema ropes MBL 2373 kN


Nylon ropes MBL 920 kN

FORWARD AFT ASTERN


3 (20, 21, 22) 1 (25) 3 (24, 26, 27)
Number of Dynema ropes 6 (1, 2, 3, 4, 5, 6) 6 (14, 15, 16, 17, 18, 19) 7 (9, 10, 13, 16, 17, 18, 19)

Mooring ropes capacity 4,730 2,172 4,878


Safty factor (pass criteria) 27 m/sec 2.6 1.2 2.6
40 m/sec 1.2 0.5 1.2

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