Warmatrix

A trireme was a war-galley with rowers seated on three banks, one man per oar. The word trireme is derived from the Latin triremis, which is derived from the Greek trieres, 'three-rower', but the ship was probably invented in the late 8th century BCE by the Phoenicians, who left no name for it. It was developed out of the pentekonter, which used only one row of oarsmen, and the bireme, which used two.
The average trireme was about 37 meters long and 3.5 wide (excluding gunwales), with a draft of around 1 meter. The ship displaced about 40 - 70 tons. It was powered by 170 rowers and carried a crew of up to 30 to steer, man the sails and fight on deck. Its shallow draft meant that it could by hauled onto, and launched from, a beach without too much trouble. This was necessary too, because it often became waterlogged. Triremes almost always made journeys of one day maximum, before beaching and loading fresh supplies for the large crew. Despite the wear and tear, a well-maintained trireme could reach a service-lifetime of 25 years. "Kataphrakatai" triremes had a closed deck above the rowers, "aphraktai" ones lacked that. They had not only oars, but one or sometimes two masts with square sails.
Triremes could travel at 1 knot going against the wind and current, on average at 4 knots for a whole day, or up to 7 - 8 when using the sails with good wind. Using only oars, the top sprinting speed was about 8 - 9 knots, which could be reached in about ½ minute. They were also very maneuverable, able to do a half-turn in a minute or so. This was vital, because the trireme's main attack was ramming. The ram was fitted to the prow of the ship, just below the waterline. Ramming was not only dangerous for the target, but also for the attacker, as the ram could get stuck in the target. Triremes also used different attacks, for instance shearing off the oars of an enemy on one side, paralyzing him. The marines could board other ships when they locked together, but this was less common.
The first triremes appeared in the late 8th century BCE, however it seems they became dominant about three centuries later. The trireme gained fame in the battle of Salamis in 480 BCE, the first time that the city of Athens built a navy. It formed the basis of their sea-empire, though all other Mediterranean coastal states used triremes too. In the 4th century BCE, it was partially made obsolete by the Romans, who, being excellent land-soldiers, used larger ships and fought by boarding rather than ramming.