specialized vessel of war that was capable of high speeds and complex maneuvers. At nearly 40 m in length, displacing almost 50 tonnes, it was more than three times as expensive as a two-level penteconter. A trireme also had an additional mast with a smaller square sail placed near the bow. Up to 170 oarsmen sat on three levels with one oar each that varied slightly in length. To accommodate three levels of oars, rowers sat staggered on three levels. Arrangements of the three levels are believed to have varied, but the most well-documented design made use of a projecting structure, or outrigger, where the oarlock in the form of a thole pin was placed. This allowed the outermost row of oarsmen enough leverage for full strokes that made efficient use of their oars. The first dedicated war galleys fitted with rams were built with a mortise and tenon technique, a so-called shell-first method. In this, the planking of the hull was strong enough to hold the ship together structurally, and was also watertight without the need for caulking. Hulls had sharp bottoms without keelsons in order to support the structure and were reinforced by transverse framing secured with dowels with nails driven through them. To prevent the hull from hogging there was a hypozoma (υπόζωμα = underbelt), a thick, doubled rope that connected bow with stern. It was kept taut to add strength to the construction along its length, but its exact design or the method of tightening is not known. The ram, the primary weapon of ancient galleys from around the 8th to the 4th century, was not attached directly on the hull but to a structure extending from it. This way the ram could twist off if got stuck after ramming rather than breaking the integrity of the hull. The ram fitting consisted of a massive, projecting timber and the ram itself was a thick bronze casting with horizontal blades that could weigh from 400 kg up to 2 tonnes. Roman era Galleys from 4th century BC up to the time of the early Roman Empire in the 1st century AD became successively larger. Three levels of oars was the practical upper limit, but it was improved on by making ships longer, broader, and heavier and placing more than one rower per oar. Naval conflict grew more intense and extensive, and by 100 BC galleys with four,