Article by Terje Engø
‘I have to say, the stability of the doors is just perfect,’ Frode Kvalsvik said. ‘But I have to add that we have only been using these doors for three months since Gollenes was delivered in April.’
This latest generation of doors, which utilise the Bluestream technology developed by Thyborøn Trawldoor, has a highly efficient water flow generated by the double foil that forces water through the doors at a higher speed to produce lift while also reducing drag.
‘Shooting these doors, especially during the sandeel fishery on relatively shallow water has been a fantastic experience. We haven’t once had the doors tilt because of contact with the bottom. This saves us time, fuel, and frustration. We are not out there to haul and shoot the trawl. We’re there to catch fish,’ Frode Kvalsvik said.
‘A common problem for trawlers is the doors tilting and falling flat in a turn. This hasn’t happened during the months Gollenes has been fishing with the new doors,’ he said, but added that right now there is a problem with the battery that results in a loss of contact with the doors.
‘But this doesn’t stop us from fishing, and the doors are still functioning very good. The battery problem will be fixed after landing. Then we’ll be going to Denmark for other reasons, and we’ll get the battery problem dealt with at the same time.’
Behind these doors is a long process of research, development and testing of the technology, including model testing in a flume tank before moving on to full-scale trials with a prototype. Getting doors off the bottom has been a central part of the development in recent years, as by flying the doors clear of the seabed there are efficiences to be made in reducing drag, as well as the benefits of minimising ground contact in semi-pelagic fisheries such as those Gollenes is part of.
‘As we speak, we’re trawling for Norway pout, and we have the doors very low, slightly touching the sea floor, but still with full control. We have been using the doors bottom trawling and for pelagic trawling for sandeel and herring. The doors have shown an impressive performance in several ways,’ he said.
‘We have until now been operating with a single trawl. After landing the catch this time, will we change to a double trawl system, using the same set of doors. This is the first time we are using doors which we can control from the wheelhouse. We can sit and follow the doors on the screens. Any changes to spread or to the depth are quick and easy. If we’re fishing for example for sandeel, we can change the towing depth by adjusting the doors to the depth we we see there’s fish,’ Frode Kvalsvik said.