Ship squat is affected by several factors, including the speed of the vessel, the block coefficient of the vessel, and the blockage factor of the canal or narrow channel.
1. Speed of the vessel-
The speed of the vessel plays a significant role in determining the amount of squat, as the faster the ship moves through the water, the more low pressure is created under the hull, leading to a greater degree of squat. It is important to note that the speed here refers to the speed through water, not the speed over ground.
2. The block coefficient of the vessel
The block coefficient of the vessel is also a crucial factor, as it determines how much water the moving ship pushes forward. A vessel with a higher block coefficient will push more water and, hence, experience more squat than a ship with a lower block coefficient, all other conditions being the same.
3. The blockage factor of the canal
Canals and narrow channels also create additional low pressure due to the restricted sideways water flow, leading to an increase in squat. The blockage factor of the canal or narrow channel can be calculated by taking the ratio of the ship’s immersed cross-section to the cross-section of water within the canal. A blockage factor of less than 0.100 represents open sea-like conditions and, hence, no blockage factor, while a blockage factor of 0.265 represents a narrow channel.