Elliott favors no more than three banks and usually two, with a quinquereme's five rowers shared among those levels. Possible distributions include three rowers on one oar and two on another, or smaller groups across three oars. Additional vertical banks would complicate coordination and make the ship increasingly unwieldy. The numerical rating therefore describes manpower per side instead of a literal count of vertically stacked banks.
Notable Point · 1:00:52-1:01:38
Why polyremes probably used only two or three oar banks
Higher polyreme numbers probably count rowers per side, avoiding an impractical tower of oar banks.