Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Structural Design and Strength Analysis of FPSO Thruster Room
Hongwei Fan, YuHan Wang, ZhiChao Chen, Huan Zhang, ShiDa Fan
Shanghai WaiGaoQiao Ship Building Co, LtdShanghai, China

ABSTRACT
According to the requirements of sailing ships, two thruster rooms

STRUCTURE DESIGN

were designed creatively at the aft end of the FPSO engine room,

According to equipment documents, the propulsion unit is composed ofand two (2) underwater dismountable azimuth type thruster units

a propulsion module, a steering module and a mounting block (shown inwere installed. Therefore, the structural design and strength ofFig.1) on which the propulsion unit is mounted.

thruster room are particularly important.

The mounting block is a double-bottom structure with 12 ribs arranged

This paper briefly introduces the structural design characteristics

evenly in the base which needed to be welded to the structures on theand structural strength analysis of the thruster room.

vessel to transfer stresses from the thruster.

KEY WORDS: Thruster Room, Thruster Foundation, Structure
Design, Strength Analysis
INTRODUCTION
In recent years, thanks to the sharp recovery in oil prices, the FPSO ship
type has been developed. However, the towing cost of FPSO is pretty
high. In order to save on the high towing costs and make the FPSO easy

Fig.1 Mounting Blockto move between oil fields, as requirement of the ship owner, weThe thruster foundation is designed depending on the specific size of thecreatively proposed to install two (2) underwater dismountable azimuth

mounting block.

type thruster units to FPSO, complete with ancillaries and additional

The thruster foundation located at the bottom of the thruster room is

power generation (Dong, T and Wang, ZX, 2007). Each thruster anddesigned with a double-bottom accordingly to align with the mounting

associated ancillaries were installed in a dedicated Thruster Room,

block. And webs are connected to the ribs and then end at bulkheads orrespectively on PS and SB against the transom of the Aft Machinery

other webs, so as to better stress transfer and reduce the structuralSpace.

deformation and impact on the thruster operation (Li, Y, and Yang, XB ,The bottom part of the thruster room was designed to integrate the2017).

housing of the dismountable thrusters.

Since the height of the mounting block is 850mm only, in order toIn order to verify the feasibility of the proposal, as part of the design, aensure sufficient strength and stiffness for the thruster room, the steel

report gave the structure analysis of the thruster and thruster room as perplate of the thruster foundation (including the double bottoms and allowner and class requirements to check thruster foundation strength inthe webs) is designed to be 30mmDH32.

service (transit conditions) and structural stiffness for the thruster

The structure details are shown in Fig.2 and Fig.3 as 3D-model.

foundation.

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