USCG Exam PracticeSingle-screw maneuvering and prop walk
A single-screw inboard vessel is backing in a short chop with weight distributed aft and low freeboard at the transom. Beyond the risk of propeller side force, what additional hazard specific to this configuration must the coxswain manage?
- A. Pivot point migration forward that reduces the coxswain's ability to control bow swing
- B. Discharge screw current setting up a following sea that overtakes the transom
- C. Increased rudder cavitation from the suction screw current drawing aerated water across the rudder face
- ✓ Shipping water over the transom that may not drain immediately, threatening stability, and drawing exhaust fumes into cabin spacesCorrect
Why D is correct
USCG Boat Crew Seamanship Manual §10-C identifies two specific cautions when backing: boats with low freeboard aft and weight aft can ship water over the transom in a chop, and water that does not drain at once threatens stability; additionally, inboards exhaust through the transom so backing can draw exhaust fumes over the crew and into cabin spaces.