USCG Exam PracticeSingle-screw maneuvering and prop walk
A single-screw vessel is backing in a choppy anchorage. The coxswain notes the vessel has low freeboard aft and weight concentrated aft. Which hazard specific to this backing evolution requires immediate consideration?
- A. Exhaust fumes drawn forward into the engine room through the suction screw current
- B. Increased propeller side force due to aeration from wave action at the stern
- ✓ Water shipped over the transom that may not drain quickly, threatening stabilityCorrect
- D. Loss of rudder effectiveness caused by the pivot point shifting forward as the vessel slows
Why C is correct
USCG Boat Crew Seamanship Manual §10-C specifically cautions that boats with low freeboard aft and weight aft can flood the afterdeck in a chop when backing, and water that does not drain at once threatens stability. This is a distinct hazard from the exhaust fume concern, which applies to crew exposure rather than stability.