The “thinarray”; a lightweight, ultra-thin (8 mm OD) towed array for use from small vessels of opportunity

Conventional towed arrays are typically 40-80 mm in diameter and weigh >1 kg/m, requiring facilities unavailable on small vessels and inconvenient for submarines. This work presents a design that uses miniature cylindrical ceramic sensors and surface mount electronics on an integrated multilayer PCB only 6 mm wide. A novel turbulence suppression technique is proposed, based on an assumption of near-isotropic turbulence structure scaling with the dimension of the towed body below a critical diameter. By making long and narrow sensors, turbulence noise is averaged incoherently while desired signals in the bandwidth up to 20 kHz are summed coherently, providing signal to turbulence noise gain. An 8 mm diameter prototype array has been constructed that can easily be handled by one person. Preliminary acoustic results are given and potential applications explored