Confronto fra le caratteristiche idrodinamiche di alcune reti a strascico di tipo italiano

Three bottom trawls of Italian design, one traditional (T3) and two experimental (T87 and T88), were tested at sea by measuring the principal behavioural parameters. A totat of 30 hauls were made at different depths. In all the tests made, the door spread measured on the three trawls resulted practically equivalent. On the contrary the horizontal opening of the T88 trawl was significantly greater than that of the T87 trawl; the T3 trawl showed the smallest horizontal opening. The T3 trawl had also the lowest vertical opening, while the T87 and T88 trawls showed about the same value for this parameter mainly when the horizontal opening reach high values. Although the increase in the vertical and horizontal opening, both the T87 and the T88 trawls did not shown a correspondent increase in the towing loads.