Most of us own cars and even though we may never have repaired an engine ourselves, we know and have seen what a piston looks like. The marine pistons are not much different in their basic principles of operation but as they say – size does matter – and when the piston being talked about belongs to the main propulsion engine or main engine of a ship, the size is really huge. Whereas the piston of your automobile or car could fit into the palm of your hand (or both palms combined together) you need to be a monster to lift the marine piston of the bigger engines