Towed-body system dynamics and interaction

With increasing motivation to reduce environmental impact, there is a push towards less installed power in ships. While calculating the performance of ships at a steady design speed is relatively straightforward, understanding more realistic ‘off-design’ conditions are more demanding. Fishing vessels that by nature operate at a range of speeds and with different load conditions, present unique problems that are as yet not well investigated. In particular, the effect of trawling and/or retrieving a heavy tow, on overall resistance is not well studied. The aim of this paper is to study the effect of a towed object, in various condition, on a fishing vessel resistance. In particular, the study investigates the change in the vessel's resistance, rather that the additional load presented by the towed object; though interaction with the Kelvin wave and towed object is also investigated. The objective is to understand and provide guidance on best practice with respect to tow length.