Influence of the towline material: Steel or high-modulus polyethylene on towing gear design and tug deck fittings

摘要

The traction force or bollard pull and specific function of a tugboat determine the size of its towing gear and deck fittings. These dimensions must enable the tug to carry out a manoeuvre safely. This article considers proposals made in the implementing regulations for calculating the length and diameter of the towline. It analyses the possibility of using high-modulus polyethylene fibre and the way it would affect the design of the towing gear and deck fittings, including the fairleads and bits. It would be useful if regulations provided further guidance on towline length for port tugs. The final part of this study analyses the solutions informed by a sample of 51 port tugs, the majority of which are escort tugs.