Marine installations in areas with fishing activities risk being damaged by the fishing gear. The risk is greatest if active fishing gear is used, such as trawls, and over-trawling of anchor lines for subsea installations is one of the most common analyses of this kind carried out by SINTEF. Such analyses can be performed using simulations or model experiments. In SINTEF's self-developed simulation software FhSim, there are models for various marine structures and fishing gear, such as net structures, ropes and cables. This allows for tailor-made analyses where a collision between fishing gear and other marine installations can be a danger. A typical example of such an interaction is over-trawling of anchor lines where the warp and the sweep in the trawl make contact with the anchor line. The capacity of the anchor line can be weakened by pulling the main wires, as well as the trawl doors themselves, over the anchor line. Such an analysis will typically include the geometry, tension and depth of the anchor line together with the fishing boat's position, course, speed and equipment rigging. Model experiments are both an alternative and a complementary method for such analyses. SINTEF has several laboratories that run such experiments, both the flume tank in Hirtshals, the towing tank in Trondheim and the sea basin in Trondheim. Here, the speed and configuration of both the trawl and the construction can be varied to test out how details can be changed to reduce the risk of damage. The outcome of such an analysis may lead to more extensive safety zones around the installation and/or reinforced anchor lines. SINTEF also helps with mapping the actual fishing activity, as well as making predictions for future activity in such situations.
