Full scale tests on the interaction between bottom fishing gear and an 18-inch marine gas pipeline in the North Sea

The paper describes the fishery side of experiments carried out by a research team from various governmental departments and the oil and gas industry on the effects of the impacts of commercial bottom-fishing gear on a partially buried, or unburied pipeline in operational use. The experiments were held early 1984 on the NAM K7/K8 18-inch gas pipeline situated on The Netherlands Continental Shelf. It was confirmed that pipelines with the new type of coatings can endure the impacts of fishing gear without ill effects on operation or safety. The forces encountered by the fishing gear, especially the beam trawl, can be considerably reduced by specially designed adaptations of the trawl head (trawl shoes) on the lines such as those developed to avoid the hooking of marine telephone cables. The forces measured in the warps are of the same order of magnitude as those measured when the gear strikes boulders or runs into sand dunes.