What is the purpose of using a catenary in towing?

Using a catenary in towing primarily serves to absorb shock in rough waters. When a vessel is being towed, especially in turbulent sea conditions, the forces exerted on the towline can vary significantly. A catenary, which involves letting the towline hang in a curve, allows for some flexibility and movement. This configuration helps to distribute the forces along the line more evenly and mitigates the impact of sudden movements or jolts caused by waves and swells.

By absorbing these shocks, the catenary reduces the risk of damage to both the towing vessel and the vessel being towed. It allows for a smoother and more controlled towing operation, increasing safety for both vessels involved. The design and geometry of the catenary ensure that the forces do not transfer abruptly, which can otherwise lead to breakage of the towline or instability in the towed vessel.