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Slam loads and kinematics of wave-piercing catamarans during bow entry events in head seas

journal contribution
posted on 2023-05-19, 22:15 authored by Babak Shabani, Jason Ali-LavroffJason Ali-Lavroff, Michael DavisMichael Davis, Damien HollowayDamien Holloway, Thomas, GA
Centre bow (CB) design for wave-piercing catamarans (WPCs) is a critical compromise between minimization of slamming and protection against deck diving. To inform the design process, this article investigates the slam loads and kinematics during bow entry events in regular head seas for a 112-mWPC with systematic variations to its CB and wet-deck geometry. Model tests using a 2.5-m hydroelastic segmented catamaran considered five different CB configurations, designated as the parent, high, low, long, and short CB. The results indicated that changes in the CB length had little effect on the general kinematic trends obtained for the pitch, heave, and bow vertical displacement at the instant of slamming, but increasing the wet-deck height resulted in an increase in heave (but not pitch) at slamming. Two new design ratios are proposed. The CB immersion depth to arch height ratio showed slamming occurring in the range of 0.3-0.6 depending on the wave encounter frequency and the CB configuration. The CB buoyancy in the encountered waves was estimated by considering both immersion depth and area along the CB in waves through relative motion analyses. It was found that the buoyancy to slam force ratio increased with increasing wet-deck height but not with increasing CB length. This suggests that an optimal CB configuration could be achieved by first modifying the arched cross-structure to reduce the arch filling effect on slamming severity and then maximizing the CB buoyancy to slam force ratio by increasing either the wet-deck height or the CB length.

History

Publication title

Journal of Ship Research

Volume

62

Pagination

134-155

ISSN

0022-4502

Department/School

School of Engineering

Publisher

Soc Naval Arch Marine Eng

Place of publication

601 Pavonia Avenue, Jersey City, USA, Nj, 07306

Rights statement

© 2018. Article copyright remains with the publisher, society or author(s) as specified within the article.

Repository Status

  • Restricted

Socio-economic Objectives

Domestic passenger water transport (e.g. ferries)

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