Trawl Resistant Shield Package (TRSP)


A Trawl Resistant Shield is being deployed from CSS Hudson.

Product Details

The TRSP is used to protect bottom-mounted equipment, primarily ADCP’s, from depredation 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 components (Argos transmitters, strobes, RDF transmitters, etc.) can limit working depth.

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

The ADCP and an acoustic 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 separate acoustic 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 acoustic release in the Instrument Housing, which allows that module to float to the surface, trailing a negative buoyancy line that is attached to the Shield. The Instrument Housing is brought aboard the vessel, and the recovery line is fed to a winch. The Shield is then winched aboard.


ADCP Shield & Mast – As Deployed

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

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