Trawl Resistant Shield Package (TRSP)

A Trawl Resistant Shield being deployed from CSS Hudson.

Product Details

The TRSP is used to protect bottom mounted equipment, primarily ADCP’s, from depradation by fishing trawls. They have been used extensively on the continental shelf of the North Atlantic, in the Gulf of Mexico and the Yellow Sea.

The TRSP has no actual working depth rating, as all modules are free-flooding. The range of the ADCP and the depth rating of the various electronic componets (Argos tramsmitters, strobes, RDF transmitters, etc.) can limit working depth.

All three modules of the TRSP are recoverable and reuseable. See Sketch of TRSP modules as given below.

The ADCP and an accoustic release are mounted in a positive buoyancy Instrument Housing, which is then placed in the Shield. The Deployment Mast is then mounted on top of the shield. Using a slack deployment line, the instrument is allowed to free-fall to the bottom. Once on the bottom, a seperate accoustic release on the Mast is triggered, and the positive buoyancy Mast floats back to the surface. The instrumentation in the Shield is left to record data.

Retrieval is accomplished by triggering the accoustic release in the Instrument Housing, which allows that module to float to the surface, trailing a negative buoyancy line which is attached to the Shield. The Instrument Housing is brought aboard the vessel, and the recovery line fed to a winch. The Shield is then winched aboard.

  Trawl Shields


ADCP Shield & Mast – As Deployed

  • Mast is used for stability during deployment
  • Once shield is on bottom, the mast acoustic release is triggered
  • Mast is then recovered using deployment line
  • When instruments are to be recovered, acoustic release inside shield is triggered
  • Instrument box inside shield releases and floats to surface
  • Instrument box trails recovery rope that is attached to box and shield
  • Instrument box is brought onboard
  • Recovery rope is fed to winch
  • Shield is winched aboard

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