There is no single 'best' hydrodynamic form for ships since there are many factors that could affect how well a vessel performs, such as the type of cargo, water depth, wave conditions, and more. For the most efficient propulsion, a ship's hull should be designed to reduce the drag forces that resist forward motion, such as waves, currents and hull friction. Generally, longer and narrower ships are thought to have the most efficient hydrodynamic form, though there are exceptions.