Cable length optimization for trawl fuel consumption reduction

A numerical method for optimization of the cable lengths in trawls with respect to the ratio between the estimated trawl drag and the predicted catch efficiency is developed and applied. The trawl cables of interest are warps, bridles, headline and footrope. The optimization algorithm applies an ordered sequential process changing one cable length at the time. It is assumed in the predictions that the catch efficiency of the trawl is proportional with the trawl mouth area. In a case study optimizing a bottom trawl used on a research vessel by applying the new method it is predicted that it would be possible to reduce the ratio between trawl drag and catch efficiency by up to 46% by optimizing the cable lengths. Thus this would enable a considerable reduction in fuel consumption to catch a specific amount of fish. Moreover, we predict an increase in the value of the trawl mouth area leading to better catching efficiency without increase in otter door drag.

► We apply energy efficiency optimization to the redesign of trawl cables.
► The redesign includes warps, bridles, selvedges, headline and footrope.
► Energy is minimized with account for fish spatial distribution.
► Our work leads to an important fuel saving that might reach 46%.
► Catching efficiency enhanced without simultaneous otter door drag increase.