Wing Trawling System

Wing Trawling System

Wing slashes fuel costs and by-catch rates

Randy Skinner is no typical Gulf of Mexico shrimp fisherman. With an instinct for engineering and design, he harnessed the CAD capability of his other business to design an alternative to the traditional flat trawl doors used by the Gulf fleet of shrimp trawlers.

This Alabama fisherman is also no newcomer to the business, with forty years of experience in catching shrimp behind in  – during which the problems of traditional doors became a longstanding challenge. He developed the first of a series of what became the Wing Trawl System – effectively a carefully engineered beam trawl designed to keep the standard shrimp trawl open and for the flow of water over the top face to pressure the wing downwards, holding it in place.

The wings are constructed in marine-grade aluminium, and to develop and refine them over successive versions he was able to use the computer-aided design CAD capabilities of Skinner Models, which produces scale ship models the US government, as well as for the fishing and oil industries.

The WTS keeps each net fully spread, no matter what. Image: ETS

Randy Skinner’s Wing Trawl System (WTS) has been through a few generations of development, each tested and put through its paces on board his own shrimper, the 65′ (19.80m), twin-engined Apache Rose, working across the seasons to try out the Wing Trawl under all weather conditions as well as across the range of depths the shrimp fleet operates. He set up Environmental Trawling Solutions as a company to continue to develop and produce the WTS.

‘There are no drawbacks that I’ve been able to find,’ he said.

The results have been startlingly successful, as the Wing Trawl has returned lower fuel costs – plus a significant reduction in by-catch, demonstrated in a comparative trial carried out with the University of New Orleans. The drop in by-catch is a major advantage that hadn’t been anticipated at the outset, as his initial goal was to develop gear that would be more economic to run.

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He explained that as the trawl approaches, the finfish that account for by-catches are presented with a choice of going to one side or the other, and then encounter the plume of silt generated by each door which herds them back into the net with the target catch of shrimp that the tickler chain rousts out of the seabed. In contrast, the arrowhead of the Wing Trawl sends the fish to either side, but there’s no silt plume to herd them back in, while shrimp are caught as they would be with a standard trawl.

‘With the University of New Orleans we carried out a trial with a Wing Trawl on one side and a standard trawl with doors on the other, over eighty tows, each of two hours,’ he said.

Randy Skinner's shrimper Apache Rose

‘We saw a 65% reduction in by-catches of finfish,’ he said, commenting that in general other by-catch reduction devices show a 10% reduction rate, at best.

He said that the lightweight Wing Trawl has a roughly two-foot seabed contact footprint, compared to the six to eight feet of each traditional door, plus the wings are not affected by the numerous variables that apply to trawl doors. As a result, the spread of the two nets towed by each Gulf shrimper from outrigger booms remains fixed through out the tow.

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‘The Wing Trawl uses 35 to 40% less fuel compared to trawl doors. That’s a reduced fuel cost but that also means a reduction in vessel up-keep and repairs to the mechanics on board,’ he said, explaining that as engine run slower and cooler with less drag from the gear, there are long-term benefits with lower demands on both propulsion and deck equipment.

‘A bottom line increase of as much as 30% can be realised with increased production and fuel savings – while achieving a by-catch reduction rate which is one of the highest in the world. Converting to a Wing Trawl is a single process as existing nets can be used and the only conversion is the removal of the trawl doors. It doesn’t matter if the vessel is small or large, and the Wing Trawl System, can be used anywhere from shallow inshore grounds to deeper ocean waters.’