Question 66 TV01 - Towing Vessels - Oceans or Near Coastal

The Correct Answer is B **Why Option B ("In all depths of water") is correct:** Vessel squat is the phenomenon where a ship underway experiences a decrease in underkeel clearance (draft increase, accompanied by a change in trim—either stern or bow down, or both). This effect is caused by the pressure drop resulting from the increased water velocity around the hull. This hydrodynamic effect occurs anytime a ship moves through the water, regardless of depth. While the magnitude of squat is significantly amplified and is most noticeable in shallow water (due to the "blockage factor" restricting return flow), the phenomenon itself is present in all depths of water, including deep ocean transits. Therefore, a vessel will squat in all depths of water, though the degree of squat will vary dramatically. **Why the other options are incorrect:** * **A) Only when in shallow water:** This is incorrect because, while squat is most severe and dangerous in shallow water, the hydrodynamic effect (pressure drop) still exists in deep water, meaning the vessel is always experiencing some degree of squat. * **C) Only when in narrow channels:** This is incorrect for the same reason as A. Squat is amplified in restricted waters (shallow *and* narrow), but the fundamental physics causing the draft increase are present everywhere. Furthermore, a vessel will squat on the open ocean (deep water). * **D) Only when in deep water:** This is incorrect because squat is a constant feature of a vessel's movement, and it is most pronounced and dangerous in the transition from deep to shallow water, not just in deep water itself.