The speed of the water flowing past the rudder greatly enhances which force?

The speed of the water flowing past the rudder greatly enhances which force?

• A. THRUST
• B. TURNING
• C. DRAG
• D. LIFT

Answer: (C)

When the rudder moves through water, it acts like a small wing in a fluid. The flowing water is deflected around the rudder, creating two forces: lift, which is perpendicular to the flow and pushes the rudder to one side, and drag, which acts along the flow and resists the movement. As water speed increases, the dynamic pressure rises with v^2, so both lift and drag increase. The turning of the boat, however, comes mainly from the lift on the rudder—the sideways force that creates a yaw moment on the hull. Drag also grows with speed but does not produce the turning effect itself; it mainly adds resistance. So the force that increases most with water speed and drives the steering action is lift, which generates the turning moment.

When the rudder moves through water, it acts like a small wing in a fluid. The flowing water is deflected around the rudder, creating two forces: lift, which is perpendicular to the flow and pushes the rudder to one side, and drag, which acts along the flow and resists the movement. As water speed increases, the dynamic pressure rises with v^2, so both lift and drag increase. The turning of the boat, however, comes mainly from the lift on the rudder—the sideways force that creates a yaw moment on the hull. Drag also grows with speed but does not produce the turning effect itself; it mainly adds resistance. So the force that increases most with water speed and drives the steering action is lift, which generates the turning moment.