starters and alternators are sealed to prevent sparks and wont blow your boat up under a hatch
carbs have j tubes to deal with sloshing fuel in the bowls to dump it back down the carb rather than all over the motor
fuel pumps have vent tubes to vent fuel into the carb
motors are built with different tolerances to deal with running at 3k-5k rpms with temp swings all the time rather than cruising at 1000-2000 like a car
