>>1543656that is a cargo boat so its speed is not fast enough for drag to be a problem
and in general boats are slower anyway
the density of water is a serious problem particularly as it does not compress
even at low speeds of around 120 kph water is apt to tear off parts of a boat with ease
most high speed boats are made to rise up out of the water
hydroplanes become suspended from two floats up front and rest a little on the trailing edge of the hull
hydrofoils lift all parts out of the water almost entirely
but either type still needs to keep the propeller low enough that it stays in the water when the boat hits a ripple in the water
in addition boats have a significant problem with cavitation
pockets of air near the edge of the propeller can overheat the water around them and cause small hydrogen detonations
the explosions chip bits off the propeller and the boat deck
