University Of Tasmania

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Twist-and-camber effects on the performance of simple hydro-sails for efficiently spreading penaeid trawls

journal contribution
posted on 2023-05-18, 15:17 authored by Balash, C, Sterling, D, Lustica, M, Broadhurst, MK
Penaeid-trawling fuel efficiency can be enhanced by using otter boards with high lift-to-drag ratios (L/D), which generally occurs at low angles of attack (AOA). The batwing otter board is such a low AOA solution; incorporating a unique towing arrangement and a high aspect ratio, flexible, hydro-sail to spread trawls with minimal seabed contact. This study investigated the effects of twist and camber on the performance of two simple batwing sails in a flume tank. Six degree-of-freedom loads were measured for AOAs between 0° and 40° for five twist and camber combinations. The major findings were that: (1) changing the mast rake angle from 30° to 45° reduced L/D at the design AOA of 20° by 12%, considering each sail’s optimum setting; (2) stall angle increased for the higher rake angle, despite the associated sail having the greater aspect ratio; (3) irrespective of rake angle, camber was positively associated with lift whereas twist decreased drag and substantially increased L/D at the design AOA; and (4) a L/D ratio of ∼3 was achieved or exceeded at 20° AOA for both sails, which is ∼3 times greater than for contemporary otter boards, implying a 20% drag reduction for otherwise equivalent penaeid-trawling systems.


Publication title

Ocean Engineering: An International Journal of Research and Development








Australian Maritime College


Pergamon-Elsevier Science Ltd

Place of publication

The Boulevard, Langford Lane, Kidlington, Oxford, England, Ox5 1Gb

Rights statement

Crown Copyright 2015 Published by Elsevier Ltd. All rights reserved.

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in engineering

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