🔍 Key Concepts

• Effect of twin-screw (twin-propeller) arrangements on maneuvering • Difference between inboard-turning and outboard-turning propellers • How transverse thrust/side force from each propeller cancels or reinforces

💭 Think About

• Visualize looking at the vessel from astern: which way is each propeller turning, and what sideways push does that give to the stern? • Ask yourself if the side forces from the port and starboard propellers are balanced or if one side’s effect is stronger overall. • Consider what happens to the vessel’s bow if both screws are putting the same power ahead but creating side forces in opposite directions.

✅ Before You Answer

• Identify clearly what “turning outboard” means for each propeller (port and starboard). • Check whether the transverse thrust from the port screw opposes or assists the transverse thrust from the starboard screw. • Confirm that with engines equal, no rudder, no wind/current, you know whether any net sideways turning moment remains.