Taking trawl doors to a new level
There has been plenty of development of trawl doors since the days when they were just that; arrays of heavy oak planks bound up in an iron frames, hence the name. WF&A's new columnist, Quentin Bates, reports.
First the materials changed as trawl doors were increasingly made in steel. Cambered and oval doors replaced the flat wooden type. Then there was a technological leap as aeronautical software began to be used to produce increasingly efficient designs, and everything changed. Trawl doors became sophisticated devices designed to stay off the bottom as environmental concerns also became a key factor.
That’s not to say that the old wooden door is a thing of the past. Far from it. If you’re towing slowly in just a few metres of water, then an inefficient flat door is likely to be exactly what you need to keep the gear open. But go deeper and you’ll want something more advanced.
Despite the huge advances made in trawl door efficiency in every way, doors remain an essentially passive device. Once the gear is in the water, changes to the gear are limited to altering towing speed and warp length. Out of the water, changes to rigging aren’t always easily made, especially without a great deal of deck space.
Being able to adjust them while towing is practically the Holy Grail of trawl doors.
The technology is all there in different places to do this, but somehow it has never worked out. The results were either too cumbersome or not effective, or else too sensitive for a trawler’s deck, or else their developers have simply been unable to attract funding to get a good idea beyond the trial stage.
Until now, that is. Icelandic trawl door producer Atli Már Jósafatsson of Polar Trawl Doors, someone who has been around trawl doors all his life, has been through the long process of developing his Poseidon doors that are genuinely controllable. Upper and lower foils can be activated and adjusted separately to increase or reduce the flow of water, making it possible to steer the door up or down, either together or independently.
The various technologies of trawl doors, batteries and remote control have all been brought together in a single package that works, if the recent trials on board Westmann Islands trawler Vestmannaey are anything to go by.
What is also noticeable about Atli’s programme is that this has been a largely solo effort. There are no committees and study groups involved, no heavy subsidies have gone into this development.
The big questions are, does it work and how much is it going to cost? We can’t answer either right now… Undoubtedly these doors are going to cost more. Technology costs money. Do they work? Judging by the trials, it looks good, and Atli has customers lined up who don’t generally make a habit of throwing their money away on gear that isn’t going to do what it says on the tin. So watch this space.
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