B. The hull experiences repeated cycles of loading and unloading due to wave action.
Fatigue stress occurs when a material is subjected to repeated cycles of loading and unloading. In a vessel, the constant motion of waves causes the hull to flex and bend, creating these cycles of stress. Over time, this can lead to cracks and structural failure if not properly addressed.
Why the other answers are incorrect:
- A. The hull is subjected to constant, static pressure from the water. This describes hydrostatic pressure, not fatigue stress. Fatigue is caused by cyclic loading.
- C. The hull is only affected by fatigue when grounded. Fatigue occurs due to repeated loading and unloading, which happens continuously while a vessel is in the water, not just when grounded.
- D. Fatigue stress does not occur in modern vessel hulls. This is incorrect. Fatigue is a real and significant issue in vessel design and maintenance.
Fatigue stress is specifically caused by the repeated loading and unloading of the hull structure due to wave action.
B. The hull experiences repeated cycles of loading and unloading due to wave action.
Fatigue stress occurs when a material is subjected to repeated cycles of loading and unloading. In a vessel, the constant motion of waves causes the hull to flex and bend, creating these cycles of stress. Over time, this can lead to cracks and structural failure if not properly addressed.
Why the other answers are incorrect:
- A. The hull is subjected to constant, static pressure from the water. This describes hydrostatic pressure, not fatigue stress. Fatigue is caused by cyclic loading.
- C. The hull is only affected by fatigue when grounded. Fatigue occurs due to repeated loading and unloading, which happens continuously while a vessel is in the water, not just when grounded.
- D. Fatigue stress does not occur in modern vessel hulls. This is incorrect. Fatigue is a real and significant issue in vessel design and maintenance.
Fatigue stress is specifically caused by the repeated loading and unloading of the hull structure due to wave action.