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

Hydrodynamic Analysis of SWATH near Islands and Reefs and Design of Its Mooring Systems
Jun YU, Xiaoming CHENG, Xinyun NI, XizhaoWANG, Zhiwen CAI, Xiaolong LIU
China Ship Scientific Research Center
Wuxi, Jiangsu, China
engineering applications. However, with the demand of island reef
construction and development, the topography changes in thehorizontal scale of catamaran along the waterline in the area near theisland reef, which can no longer be expressed by uniform water depth.
The change of topography affects the wave propagation, thus
affecting the response of the floating body under waves. Therefore, itis necessary to consider the influence of terrain change onhydrodynamic performance when studying the hydrodynamic
response of floating bodies near islands and reefs. However, theexisting research results show that there is little research on thisaspect, and it is difficult to consider the terrain change. Scholars havecarried out some research on hydrodynamic performance of SWATH
and hydrodynamic interference between shallow water topography
and floating body. Lee et al. (1977) conducted three types ofexperiments which includes calm-water towing, forced oscillation andtowing to determine the hydrodynamic coefficients. They found thatthe trend of the hydrodynamic coefficient with respect to frequency
and speed. Djatmiko (1987) presented experimental data of SWATH
motions, and compared the experimental data with the theoreticalpredictions based on existing two-dimensional strip theory andthree-dimensional sink-source technique. Hart and Kiesow (1988)
Conducted vertical plane oscillation experiments on several SWATH
designs in development by the U.S. Navy. The results provided useful
information in the development and validation of SWATH
seakeeping prediction. Hart (1989) provides experimental results
defining the stability boundary for the roll motion of a SWATH
drifting in beam seas using a nonlinear math model of the coupledheave roll response. Buchner (2006) studied two body diffraction
analysis and found that wave height increased on slope as the total
wave energy remains constant while progressing into shallow water.
Ferreira and Newman (2009) compared the diffraction effects ofdifferent sloping bottom configurations. They found that differencesin depth at the bow and stern do have a substantial effect on thecross-coupling coefficients, especially the abrupt change of the sideand rear of the slope will produce refraction and reflection effects.
Eloot and Vantorre (2011) studied ship bottom hydrodynamic
interaction in shallow water through experimental fluid dynamics.
Vernengo and Bruzzone (2016) presented the hydrodynamic analysis
of a SWATH suitable for various applications such as small andmedium size passenger ferries which aims to perform a preliminary
assessment of the hydrodynamic performance of a hull with such acomplex shape in terms of seakeeping capability in regular headwaves. Feng et al. (2016, 2017) adopted a continuous rankine source
method to investigate water wave problems in an environment with aflat or sloping rigid seabed. The influences of uneven seabeds on theABSTRACT
A coupling hydrodynamic model of SWATH and reef topography
was established based on the conventional potential flow theory andthe incident wave force, diffraction force, radiation hydrodynamic
coefficients motions of SWATH were calculated. The model wascompared with the same SWATH in the uniform depth of water
without the effect of topography. Furthermore a flexible mooring
system with three mooring lines is also designed to further strengthen
the stability of the SWATH followed by the time domain analysis toassess the hydrodynamic forces motion responses and mooring
system performance in various environmental conditions including
waves and current. The method provides a useful and efficient tool
for the evaluation of the performances of SWATH coupled with reef
topography and waves and current.
KEY WORDS: Hydrodynamic analysis; reef topography; SWATH;
mooring system.

INTRODUCTION
Exploitation and utilization of marine resources including islands andreefs has become an important trend of economic and technologicaldevelopment. The surrounding islands and reefs are surrounded byreef plates with a width of hundreds of meters to thousands of metersand shallow water depth. These reef plates not only have abundantfishery and tourism resources, but also play an important role inprotecting the island from waves and preventing seawater fromeroding the island itself. The application of floating structures as thefront station of the development near the islands and reefs can provide
a foundation for the construction and resource development of islands
and reefs without affecting the ecological environment. The Small
Water-Plane Area Twin Hull(SWATH) is a new and high-tech ship
design scheme for seakeeping. Most of the drainage volume of theship is placed below the waterline. On the premise of meeting therequirements of hydrodynamics and structure, the waterline area isreduced as much as possible, and the wave force and motion responseof the ship are reduced. The design concept of catamaran can provide
a wide deck area for ships. Scientific exploration in the sea area near
the island reef is characterized by rapid deployment and flexible use.
Traditionally, the method of finite uniform water depth or infinite
water depth is usually used to calculate the motion response offloating bodies. For deep sea areas or sea areas with little topographic
change, the calculation results can already meet the needs of3829