Q.What is bank effect of a ship ?

In a restricted channel, when the ship moves near the bank, the bow is pushed away from the bank, an effect known as bow cushion, and the vessel is bodily attracted toward the bank, an effect known as bank suction. The bank cushion results from high pressure buildup between the bank and the bow of the ship, and the bank suction is caused by loss of pressure and increased velocity of water in the restricted space between the vessel and the bank.