Question

A ship with a standard right-handed coordinate system has positive \(x\), \(y\), and \(z\) axes respectively pointing towards bow, starboard, and down as shown in the figure. If the ship takes a starboard turn, then the drift angle, sway velocity, and the heel angle of the ship for a steady yaw rate respectively are: 

• A. Positive, negative, and positive
• B. Negative, positive, and positive
• C. Negative, positive, and negative
• D. Positive, negative, and negative

Hint:

When analyzing ship motions, use the standard right-handed coordinate system to determine the direction of drift, sway, and heel for specific maneuvers.

Answer 1

The Correct Option is D

Step 1: Understanding the right-handed coordinate system. 
In the standard right-handed coordinate system for a ship: - The \( x \)-axis points forward (towards the bow), - The \( y \)-axis points to the starboard side, - The \( z \)-axis points downward. A starboard turn involves a steady yaw motion (rotation about the \( z \)-axis), causing changes in drift angle, sway velocity, and heel angle. 
Step 2: Analyze the drift angle. 
The drift angle is the angle between the direction of motion of the ship and its heading. For a starboard turn, the drift angle is positive because the ship's actual motion shifts towards the port side. 
Step 3: Analyze the sway velocity. 
Sway velocity is the velocity along the \( y \)-axis (starboard direction). During a starboard turn, the sway velocity is negative as the ship moves slightly towards the port side. 
Step 4: Analyze the heel angle. 
The heel angle is the inclination of the ship about the \( x \)-axis. For a starboard turn, centrifugal forces cause the ship to heel towards the port side, resulting in a negative heel angle. 

Conclusion: For a steady yaw rate during a starboard turn, the drift angle, sway velocity, and heel angle are positive, negative, and negative respectively.