The forces and moments induced by the vicinity of banks on a sailing vessel are known as bank effects. An extensive set of model tests have been carried out to investigate bank effects induced by sloped surface-piercing as well as submerged banks. The influence of the geometry of the bank, and the height of the submerged platform in particular, on the magnitude of the bank effects is investigated. A parameter to define the distance to a bank with an irregular geometry is proposed as well as an expression for the effective water depth of a ship sailing above an irregular bottom. A formula is given for the maximal distance between ship and bank to have a significant influence of this bank on the ship hydrodynamics.