Shrimp boat operators use two trawl retrieval mechanisms mounted on the same winch frame. The main spools are used in the first operation; the shrimpers stand within inches of rotating cathead drums and guide incoming wire rope onto the main spools. Second, lazy lines are wrapped multiple times around each of the two spinning catheads (horizontal beams that raise and secure the anchor). Lastly, the guarding ends are pulled by the operators to cinch the rope to the rotating spool aiding trawl retrieval, but poses a hazard for operators to get entangled in the spinning cathead spools.

Researchers at NIOSH have developed guarding devices to protect shrimp boat winch operators from being entangled in the continuously spinning cathead spools. The mechanical guards feature a swinging functionality covering the catheads after the main trawl operations, allowing access to the normal operation of the catheads.