Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering ConferenceShanghai, 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

Typical Damage Analysis and Updating Research of Hovercraft Flexible Skirt Finger
Zongke Zhang1, Haipeng Zhang1, Yifan Xiong1, Yujia Tang2, Liwei Wan1, Shengjie Xu3
1. Marine Design & Research Institute of China, Shanghai, China
2. Shanghai HaiXun Mechanical and Electronic Corporation, Shanghai, China
3. State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai, Chinaskirt have more possibility of damage and higher replacement
frequency. Effected by ACV trim, velocity and sideslip in highfrequency, force acted on side skirt finger was more complex andchangeable (Chen, Zhu, Gu, Gao, 2021). Following will analysis
loading characteristic of fingers located at bow, side, stern, and forward
some attentions need to pay to finger structure design.

ABSTRACT
When hovercraft flies on cushion at high speed, only skirt fingers
below skirt bag contact with operating surface of water or land, which
endures complex loading at harsh operation environment. Side skirt
fingers were prone to damage and caused huge cost of damaged finger
replacement. Through analysis, it could found that operating trim
attitude and forward with sideslip are the main reasons for side finger
with more likely damage. Based on application development in
ABAQUS, skirt finger deformation after immersed into water was
digital simulated, which agreed with actual damage mode. Throughanalysis, advice for enhance life of side skirt finger were presented andalso attentions need to be pay on its membrane structure design.

STATUS OF SKIRT FINGER DAMAGE
High-pressure cushion would generate water wave under skirt during
forward at high velocity. The cushion-generated wave would induce
trim with bow-up and make aft fingers of side skirt immersed into
water, as illustrated in Fig. 1.

KEY WORDS: air cushion vehicle, flexible skirt, deform after
immerged intodevelopment

water,

simulation

byABAQUS,

application

INTRODUCTION
Hovercraft (Air Cushion Vehicle) flexible skirt attached around theentire side-low and bottom edges of hull buoyancy box, would inflate
into design shape acted by high pressure airflow from lift fan to formcushion and hover the hull over operating surface(Yun and Bliault,2000). As one of the unit systems of ACV, flexible skirt is fabricatedby thin rubber coated material and belongs to membrane type structure.
The upper part of typical skirt is continuous bags, with individual
fingers attached to the bottom of bow and side bag, while a lot ofindividual cones or little loops attached to stern bag (Ma and Wu, 2012).
The function of flexible skirt is similar to hull shell of traditional
displacement ship, which endures slapping and erosion of wave,
friction and crash of terrain, undulate ground surface and obstacle. So,
skirt belongs to life piece, and loads acted on skirt fingers are moresophisticated and ugly, which result in damage to finger low tip andshorter life. Wiggins et al. tested finger deform of bow seals immersed
into water at the US Navy’s Large Cavitation Channel and also
processed by analytical/numerical approaches, some new details werefound (Wiggins, 2014), (.García-Espinosa, 2015). “At sea” experienceon full scale ship displayed that skirt fingers located at aft part of side3807

Fig. 1. Only aft part of side skirt fingers immersed into water for ACV
at high post-hump speed
Since the trim fluctuates slightly during seaway, the followed depth
variation of finger immersed into water would result in changing bend
scope in finger foreface. The bending would cause rubber delaminationfrom core fabric scrim, especially to area near the vertical center line offoreface, where abrasion and small holes occurs and following extends
to local tear and fray, as shown in Fig. 2 (Amyot, 1989).
The peripheral skirt of English Channel ferry SRN4 of BHC wasdivided into several segments, where Seg 1#, 2A, 2B locates in bow,Seg 3# ~ Seg 9# locates at side, as shown in Fig. 3 (Wheeler, 1969).