Why were early warships long and narrow?

Early warships were designed to be long and narrow primarily to meet the essential requirements of naval warfare: speed, the capacity to carry a large number of fighting men, and the ability to maneuver effectively in any direction at any time.1

In contrast to cargo ships, which were built with rounder hulls to maximize tonnage and efficiency, the long, narrow design of rowed warships allowed them to be propelled by oars with the agility needed for combat. This shape was particularly advantageous for the tactics of the era, which often involved ramming and boarding enemy vessels. By maintaining a slender profile, these ships could achieve the necessary speed and responsiveness to engage opponents in close-quarters combat.1234

As naval technology evolved, the limitations of these long, narrow galleys—such as their lack of endurance and vulnerability in rough seas—eventually led to the development of heavier, decked-over ships and, later, the transition to sail-powered ships of the line.125