stylistic:tone, information:extraction, structural:summarization, structural:expansion
Design and construction

The documentary evidence for the construction of ancient galleys is fragmentary, particularly in pre-Roman times. Plans and schematics in the modern sense did not exist until around the 17th century and nothing comparable has survived from ancient times. How galleys were constructed has therefore been a matter of looking at circumstantial evidence in literature, art, coinage and monuments that include ships, some of them actually in natural size. Since the war galleys floated even with a ruptured hull and virtually never had any ballast or heavy cargo that could sink them, almost no wrecks have so far been found.

On the funerary monument of the Egyptian king Sahure (2487–2475 BC) in Abusir, there are relief images of vessels with a marked sheer (the upward curvature at each end of the hull) and seven pairs of oars along its side, a number that was likely to have been symbolical rather than a realistic depiction, and steering oars in the stern. These vessels have only one mast and vertical stems and sternposts, with the front decorated with an Eye of Horus, the first example of such a decoration. The eye was later used by other Mediterranean cultures to decorate seagoing craft in the belief that it helped to guide the ship safely to its destination. The early Egyptian vessels apparently lacked a keel. To provide a stiffening along its length, they had large cables, trusses, connecting stem and stern resting on massive crutches on deck. They were held in tension to avoid hogging while at sea (bending the ship's construction upward in the middle). In the 15th century BC, Egyptian galley-like craft were still depicted with the distinctive extreme sheer, but had by then developed the distinctive forward-curving stern decorations with ornaments in the shape of lotus flowers. They had possibly developed a primitive type of keel, but still retained the large cables intended to prevent hogging.

The construction of the earliest oared vessels is mostly unknown and highly conjectural. They likely used a mortise construction, but were sewn together rather than pinned together with nails and dowels. Being completely open, they were rowed (or even paddled) from the open deck, and likely had "ram entries", projections from the bow lowered the resistance of moving through water, making them slightly more hydrodynamic. The first true galleys, the triaconters (literally "thirty-oarers") and penteconters ("fifty-oarers") were developed from these early designs and set the standard for the larger designs that would come later. They were rowed on only one level, which made them fairly slow, likely only about 10 km/h (6 mph). By the 8th century BC the first galleys rowed at two levels had been developed, among the earliest being the two-level penteconters which were considerably shorter than the one-level equivalents, and therefore more maneuverable. They were an estimated 25 m in length and displaced 15 tonnes with 25 pairs of oars. These could have reached an estimated top speed of up to 14 km/h (9 mph), making them the first genuine warships when fitted with bow rams. They were equipped with a single square sail on mast set roughly halfway along the length of the hull.