In the ancient world, naval combat relied on two methods: boarding and ramming. Artillery in the form of ballistas and catapults was widespread, especially in later centuries, but its inherent technical limitations meant that it could not play a decisive role in combat. The method for boarding was to brush alongside the enemy ship, with oars drawn in, in order to break the enemy’s oars and render the ship immobile, to be finished off as convenient.
Rams (embolon) were fitted to the prows of warships, and were used to rupture the hull of the enemy ship. The preferred method of attack was to come in from astern, with the aim not of creating a single hole, but of rupturing as big a length of the enemy vessel as possible. The speed necessary for a successful impact depended on the angle of attack; the greater the angle, the lesser the speed required. At 60 degrees, 4 knots was enough to penetrate the hull, while it increased to 8 knots at 30 degrees. If the target for some reason was in motion in the direction of the attacker, even less speed was required, and especially if the hit came amidships. The Athenians especially became masters in the art of ramming, using light, un-decked (aphraktai) triremes.
In either case, the masts and railings of the ship were taken down prior to engagement to reduce the opportunities for opponents’ grappling hooks.