USCG Exam PracticeTwin-screw vessel handling
On a twin-screw vessel, what is the PRIMARY effect of increasing the RPM difference between the two engines?
- A. It shifts the pivot point forward.
- B. It increases the vessel's speed through the water.
- ✓ It changes the vessel's heading.Correct
- D. It reduces propeller side force on both shafts.
Why C is correct
Any difference in thrust between the two engines changes the boat's heading. The range runs from a small RPM difference used to hold a course up to splitting the throttles to turn the boat through 360°. (USCG Boat Crew Seamanship Manual §10-D)