A Trawl-Proof Housing for Bottom Mounted Instruments

A method is proposed to protect bottom mounted oceanographic instruments from damage caused by bottom trawls. The protective housing is a truncated pyramid approximately 50 cm high, 3 m wide and 4 m long. The instrument to be protected, i.e. doppler current profiler or tide gauge, is mounted in a central package which will float to the surface when an acoustic release is triggered. The housing´s low profile and shallow sloped sides will allow the various parts of a fishing trawl to slide over the instrument package with no damage to the instrument or the trawl. The housing is being developed initially to protect an Acoustic Doppler Current Profiler (ADCP) to be deployed on the Grand Banks of Newfoundland. The design would be applicable to protect any instrument which is less than 50 cm high.