Model of Trireme

A model of a fifth-century Trireme on display in the Malta Maritime Museum.

A trireme was a war galley that sometimes had a square sail.  It was powered by 156 oars; 78 on each side of the ship in three superimposed rows.  This long ship served as an oar-powered torpedo and the heavy ram on the bow (right side of image), just below the water line, was used to ram other ships—disabling them.

To view a small modern reconstruction of such a ship, but with only one bank of oars, see Here.