It has taken a few years, and the pandemic that temporarily brought travel to a halt didn’t help in the development process, but the extended test phase for Thyborøn Trawldoor’s fully controllable trawl doors is over
According to the company’s Henrik Andreassen, the feedback from the skipper and crew of Swedish pelagic vessel Themis, which was the test bench for the controllable Type 32s, has confirmed that the systems work as expected.
“We are that satisfied with the feedback from Themis and we have now made these trawl doors 100% available commercially. We’re open to supplying and customising systems for each of our customers who need a set of controllable doors,” he said, commenting that Themis has used the doors for a variety of fisheries and the crew are convinced that there are advantages compared to older regular pelagic doors.
The first commercial pairs have also been supplied, with Shetland pelagic vessel Serene taking a pair of the new doors after spending time in Skagen for maintenance, during which a short trial with the 15-square-metre doors was carried out.
In co-operation with Seamech, the Thyborøn team also mounted the new acoustic hydrophones alongside Serene’s existing underwater array, and the software for the controllable pelagic doors was incorporated into the wheelhouse systems.
“On the trials with Serene we shot the doors with a pre-set to maintain them at 30 metres below the surface. This was tested with different warp lengths and everything stayed in line,” Henrik Andreassen said.
The depth pre-set is just one of the array of features that allow the doors to be controlled during a tow via the wireless communication system.
“The feedback from Themis was that this is very beneficial when the crew are asleep and the skipper wants to make a small adjustment during the night. He can just change the setup on the trawl doors without having to wake up four or five guys,” he said.
Previously, Thyborøn had developed its Flipper doors, in which upper and lower panels could be folded back to adjust the overall surface area of the doors, and the manually adjustable doors with a hydraulic pump used to make alterations to the aspect of the foils whenever the skipper needed to make a change between tows.
There’s also a safety aspect to this, as now that this is done remotely, the crew no longer need to go near the doors for adjustments to be made
The surface area of the controllable Type 32 Bluestreams can be adjusted by up to 27% using the remote technology installed on board the catching vessel.
“If you have 15-square-metre doors, then you have every size covered all the way down to 10.95 square metres. This is a real benefit for vessels operating across different fisheries,” he commented.
Serene sailed home from Skagen with its new 15-square-metre doors hung at the stern ready for use, as well as with a second set of 15 square metre Bluestreams on board for Antares, and these are already prepared for the full-control technology.
