What is the term for the increase in ship draft due to reduced under keel clearance in shallow water?

• A. Squat
• B. Sinkage
• C. Tide
• D. Neap Tide

Answer: (B)

The term that describes the increase in ship draft due to reduced under keel clearance in shallow water is known as "squat." When a ship moves through shallow water, the confined space can cause the water to be displaced in a way that affects the ship's buoyancy, making it sit lower in the water than it would in deeper water. This phenomenon occurs because as the ship moves, it creates a suction effect that can draw it further down, increasing the draft and reducing its under keel clearance.

While "sinkage" refers to the general concept of a vessel losing buoyancy or rising due to various factors, it is not the precise term used for the specific situation that occurs in shallow water transit. Terms like "tide" and "neap tide" relate to the levels of water influenced by gravitational forces and do not pertain to the conditions experienced by a ship in relation to shallow water. Understanding the squat effect is crucial for navigators and officers when assessing the safe movement of vessels in shallow areas to prevent grounding or damaging the hull.