Dynamic Simulation of a Two-Part Underwater Tow

The trajectory of a submerged body being towed by a surface vessel is affected by the wave induced motion of the latter. In an effort to decouple this motion, a two-part tow configuration has been employed. This paper describes a computer model developed to investigate the decoupling effect and to predict the trajectory of the towed object. The two cables are modelled separately as a series of lumped masses connected by elastic segments, and then dynamically interlaced. The solution to the dynamic equations describing the motion of the masses subject to specific boundary conditions is then carried out using numerical techniques. This enables the investigation of the effect of varying the point of attachment between the cables and to include systems consisting of multiple towed objects. The model is to be validated by scaled model tests in a circulating water channel and full scale trials at a later date.