There is increasing worldwide concern about ship-generated waves, also known as 'ship wash'. It can be responsible for nuisance or damage to moored vessels or to other ships using the same waterways. It can cause erosion of waterway banks or beaches. The current concern often involves fast ferries or the increased speeds of full block ships operating in restricted waterways, and is further fostered by a growing awareness of potentially negative impact in sensitive natural areas. Thus, while concrete legal limits imposed on wash are still a rarity, there is an increasing demand for early specifications of how much wash new vessels will generate.