USCG Exam PracticeSingle-screw maneuvering and prop walk
On a single-screw vessel, if propeller side force is pushing the stern to starboard while backing and rudder alone cannot correct it, the coxswain should:
- A. Shift the rudder hard to starboard to redirect the discharge current and counteract the swing
- ✓ Apply a short burst ahead with the rudder shifted, using side force and discharge current to walk the stern back to portCorrect
- C. Reduce power to idle astern and wait for the suction current to stabilize before correcting
- D. Increase astern power to build sternway faster, which will improve rudder authority
Why B is correct
USCG Boat Crew Seamanship Manual §10-C states that if the stern's swing cannot be held with rudder alone, a short burst ahead uses side force and discharge current across the shifted rudder to walk the stern back the other way, using no more power than needed so sternway is not killed and a worsening discharge current is not created.