Fishing and Gear Technology

11.2.2.Trawl diagram

Unit 12 - Trawl fishing gear and operation

11.2.Trawl Diagram

11.2.2.Trawl net parts

Top Wing - The two sections of netting forming the upper pats of the mouth of the trawl, to which the Headline is attached along the inner edges.
Square – The upper trapezoids panel of netting leading forward of the baitings, to which the top wings are attached. This forms the forward running cover to restrict the upward escape of fish.
Baitings or upper Bellies – The upper part of the tapered funnel of the net that guides the fish towards the codend.
Lower Wing – The lower part of the trawl mouth that is directly below the top wings. The inner edge of this is attached to the fishing line beneath the square.
Bunt – This is a continuation of the lower wing that is attached beneath the square.
Lower bellies – The lower part of the funnel of the net that guides fish towards the codend.
Extension or Lengthening Piece – This is a continuation of the belly, and is usually rectangular like the codend. It may be inserted to improve the flow of the net, close the meshes in front of the codend or to make the hauling of the codend easier.
Codend – This is the final section of netting, usually constructed from a heavier or double netting. That is used to hold the catch of fish.
Flapper – A panel or panels of netting inserted inside the trawl to prevent or restrict the escape of fish from the aft part of the trawl. This is usually positioned in the after part of the belly or extension.
Lifting Bag – A cover over the codend that is normally made of a larger mesh size and is used to strengthen the codend whilst lifting the catch aboard.
Chafers – Pieces of netting; rubber matting or hide that are attached to the lower side of the codend and bellies to reduce damage from ground contact.
Dolls – Pieces of stranded rope that are cow hitched through the meshes on the underside of a trawl or chaffer to help protect the net from damage. These are usually used on nets that are being worked on stony ground, and are most commonly found on the underside of beam trawls. Dolls also help to block the meshes hence reducing the effective mesh size.
Wing Tips – These are triangular sections of netting found at the forward ends of the mouth of some trawls.
Side Panels – Sections of netting that are placed between the upper and lower parts to change the cross sectional shape of the trawl and give it 4 seams.
Headline – the upper rope framing the mouth of the trawl to which the headline floats are attached.
Fishing Line – The lower framing rope at the mouth of the trawl to which the foot rope, bobbins or ground rope is attached.
Bolsh – A rope that may be inserted between the wings and a framing rope.
Wing Lines – Ropes that frame the wing ends of a trawl.
Belly Lines and Selvedge Lines – These are ropes that run along seams in the trawl to give additional strength. The trawl is held open vertically by the floats attached to headline. It retains contact with the sea bed by the weight of the ground rope. The trawl is held open laterally by the otter boards, which also act as a major weight force to keep the gear on the sea bed.
A series of sweeps and bridles connect the otter boards to the trawl. These may have considerable length and are used to herd the fish to the mouth of the trawl. Tensions in these wires may also be adjusted to control the engineering performance of the gears.