Transverse thrust is the sideward force generated by a ship’s propeller.
In the case of a ship with a single right-handed propeller and a centerline rudder, the initial stages of getting underway involve high RPM ahead of the engine and propeller, but low vessel speed.
During this period, the transverse thrust is directed to starboard, causing the ship to turn to port. It’s worth noting that as the depth of the water increases, the pressure on the top and bottom blades of the propeller differs due to the higher pressure on the deeper blades.
This pressure difference causes the top blade to experience reduced pressure due to turbulence, while the bottom blade experiences greater pressure. As the ship gains headway, the turbulence decreases, and the pressure on the top blade increases.
The top blades of a right-handed propeller push water forward and to starboard, while the bottom blades push water to port. This results in the bottom blade pushing water to port more than the top blade is pushing water to starboard.
Consequently, the ship swings to starboard at the aft, which directs the ship’s forward to port.