Squat Effect
The squat effect is a hydrodynamic phenomenon that occurs when a ship moves through shallow or restricted waters, causing the vessel to sink deeper into the water than its normal draft.

When a ship is underway, water flows around and beneath the hull. In shallow water, the space between the seabed and the ship’s bottom becomes limited. Because of this restricted space, the water flowing under the hull speeds up. According to fluid principles, when water velocity increases, pressure decreases.

This drop in pressure reduces the upward support (buoyancy) acting on the ship, resulting in a temporary sinkage or increase in draft, known as squat.

Squat does not always happen evenly. The vessel may trim by the bow or stern, depending on its hull form and loading condition.

Key Factors Affecting Squat
* Speed – The faster the ship moves, the greater the squat effect
* Water depth – Shallower water increases squat
* Under-keel clearance – Less clearance means higher risk
* Hull form – Full-form ships (like tankers) behave differently from fine-form ships