Oceanographic midwater trawl for horizontal or oblique tows The IKMT Isaacs-Kidd Midwater Trawl Net (also known as HPN Hamburg Plankton Net) is the standard net for collection of larger quantities of macrozoplankton and micronekton. A wide U-shaped diving vane (depressor) keeps the mouth of the net open and exerts a depressing force, keeping the trawl net in any desired depth for extended periods at towing speeds from 0.5 to 4 knots.
Due to the design of the bridle and the position of the spreader bar the mouth opening of the net is unobstructed by the towing cable. For the security of the IKMT a predetermined breaking-point has been constructed into the bridle, which makes the net collapse when the dynamic pressure becomes too strong. The IKMT is equipped with a net bag of MOnyl with 500 μm mesh size (or as per choice between 500 and 1000 μm). The mouth opening of the net comes to approx. 7 m², the overall length is 10 meters. The fine-meshed net is supported by a coarse-meshed covering net and 5 webbings along the net.
