I had written a detailed post on squat effect on ships. You can read that by clicking below link.
In short, squat effect is the decrease in under keel clearance of the ship because of a ship moving in shallow water. When a ship moves in shallow water, there is a low pressure created under the ship because of Bernoulli's theorem.
There are 3 main factors that affects Squat
- Speed of the ship
- Block coefficient
- Blockage factor of canal
Squat must be taken into consideration when calculating the under keel clearance of the vessel.