The Athenian trireme was about 150 feet in length with a beam of 20 feet. The beam was therefore only 2/15 of the length. (A merchant ship of the same period was about 180 feet long with a beam of 1/4 its length.) The trireme was fitted with one mast and square sail, the latter being used only when the wind was fair, as auxiliary to the oars, especially when it needed to retire from battle. In fact, the phrase "hoist the sail" came to be used colloquially like our "turn tail" as a term for running away.
The triremes carried two sails, usually made of linen, a larger one used in cruising and a smaller one for emergency in battle. Before action it was customary to stow the larger sail on shore, and the mast itself was lowered to prevent its snapping under the shock of ramming.
The forward part of the trireme was constructed with a view to effectiveness in ramming. Massive catheads projected far enough to rip away the upper works of an enemy, while the bronze beak at the waterline drove into her hull. This beak, or ram, was constructed of a core of timber heavily sheathed with bronze, presenting three teeth. Although the ram was the prime weapon of the ship, it often became so badly wrenched in collision as to start the whole forward part of the vessel leaking.
The rowers were seated on benches fitted into a rectangular structure inside the hull. These benches were so compactly adjusted that the naval architects allowed only two feet of freeboard for every bank of oars. Thus the Roman quinquiremes of the Punic wars stood only about ten feet above water. The covering of this rectangular structure formed a sort of hurricane deck, standing about three feet above the gangway that ran around the ship at about the level of the bulwarks. This gangway and upper deck formed the platform for the fighting men in battle. Sometimes the open space between the hurricane deck and the gangway was fenced in with shields or screens to protect the rowers of the uppermost bank of oars from the arrows and javelins of the enemy.
The complement of a trireme amounted to about 200 men. The captain, or "trierarch," commanded implicit obedience. Under him were a sailing master, various petty officers, sailors, soldiers or marines, and oarsmen.