vessel in place of a rowing bench, usually on the port (left) side. Propulsion Throughout their long history, galleys relied on rowing as the most important means of propulsion. The arrangement of rowers during the 1st millennium BC developed gradually from a single row up to three rows arranged in a complex, staggered seating arrangement. Anything above three levels, however, proved to be physically impracticable. Initially, there was only one rower per oar, but the number steadily increased, with a number of different combinations of rowers per oar and rows of oars. The ancient terms for galleys was based on the numbers of rows or rowers plying the oars, not the number of rows of oars. Today it is best known by a modernized Latin terminology based on numerals with the ending "-reme" from rēmus, "oar". A trireme was a ship with three rows of oarsmen, a quadrireme four, a hexareme six, and so forth. There were warships that ran up to ten or even eleven rows, but anything above six was rare. A huge forty-rowed ship was built during the reign of Ptolemy IV in Egypt. Little is known about its design, but it is assumed to have been an impractical prestige vessel. Rowing Ancient rowing was done in a fixed seated position, the most effective rowing position, with rowers facing the stern. A sliding stroke, which provided the strength from both legs as well as the arms, was suggested by earlier historians, but no conclusive evidence has supported it. Practical experiments with the full-scale reconstruction Olympias has shown that there was insufficient space, while moving or rolling seats would have been highly impractical to construct with ancient methods. Rowers in ancient war galleys sat below the upper deck with little view of their surroundings. The rowing was therefore managed by supervisors, and coordinated with pipes or rhythmic chanting. Galleys were highly maneuverable, able to turn on their axis or even to row backward, though it required a skilled and experienced crew. In galleys with an arrangement of three men per oar, all would be seated, but the rower furthest inboard would perform a stand-and-sit stroke, getting up on his feet to push the oar forward, and then sitting down again to pull it back. The faster a vessel travels, the more energy it uses. Reaching high speed requires energy which a human-powered vessel is incapable of producing. Oar