Big waves and high winds will cause your vessel to go unstable and crash. Ocean-crossing cargo vessels have to handle all weather conditions. Hydrofoils signif

Big waves and high winds will cause your vessel to go unstable and crash. Ocean-crossing cargo vessels have to handle all weather conditions. Hydrofoils significantly increase draft and nobody wants to dredge their ports and canals 20 feet deeper. Also drag is proportional to velocity squared, so you can save a ton of fuel just by slowing down a bit. Much easier than designing a hydrofoil cargo ship.