Ekkó trawl doors ready to go into production
Trawl doors manufactured by Icelandic company Ekkó have been in use for two years on board research vessel Bjarni Sæmundsson, and HB Grandi’s fresher trawler has also had a pair on board for testing – with successful results, according to Ekkó’s Smári
He explained that the Ekkó doors he has developed are based around the wing concept, harnessing the full effects of Bernoulli’s Principle to work in opening the trawl.
“This saves a great deal of energy when trawling – and fuel is a major factor in any fishing company’s running costs,” he said, commenting that the research and development phase began in 2015 with three rounds of model tests in Canada that provided promising results.
“Verkís worked on the detailed computational fluid dynamics for us and came up with an improved version that was tested in the flume tank in Hirtshals earlier this year with some fantastic results. Normally a CL/CD coefficient of between 3 and 4 is reckoned to be good, but the Ekkó doors showed a figure of 5.4, which is a revolution in efficiency and energy management.”
One of the key features of the Ekkó design is the water and air valves. This allows the doors to fill with water, but as the doors are hauled up to the gallows, they do not empty completely. The water remaining in the lower section of each door helps when they are shot back, and the doors then refill in a matter of seconds.
“The air valve is made active or inactive by fitting or removing a single bolt in the upper plate of each door. When the air valve is active, the doors sit higher in the water,” Smári Jósafatsson explained.
“There is no need for Ekkó doors to touch the seabed when bottom trawling, so there is less disturbance to the seabed and benthos than with conventional doors. Ekkó doors have been used on board Bjarni Sæmundsson for the last two years, both with a demersal shrimp trawl and with pelagic gear for herring and capelin research. Along with the trials carried out on board Helga María, this has provided us with a great deal of fishing experience with these doors, which has made it possible to make fine adjustments to them,” he said, adding that the next step is to have the first commercial sets of Ekkó doors produced for various trawl sizes.
“What we have seen is that the doors are good to shoot, they open well, handle well in a turn and a responsive. The Bernoulli effect provides the lift that squares the doors by themselves and the double wing form saves energy. We have seen that resistance and water turbulence around the doors is very low, so they are quiet in the water so the fish are less likely to be spooked as the doors pass them,” Smári Jósafatsson said.
The Ekkó doors have been designed for ease of adjustment, with weights that can be added to or removed from a closed section of each door, representing a significant safety feature. A further feature is that backstrops can be rigged either to the backs of the doors, or to the front, so that both backstrops and warp are connected on the same side of each door.
The research and development phase came to an end in May this year and commercial production is the next step, with a range that includes pelagic doors, semi-pelagic doors that can be fitted with wear shoes if required, and bottom doors with wear shoes.
‘We will be manufacturing Ekkó doors in Iceland and Denmark for the northern European market,” he said.
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