Q&A: How large did Roman war galleys become?

What was the largest class of Roman warship?

Seven- and eight-class galleys are reasonably attested, with larger possibilities debated and concentrated in accounts of Actium.

A galley's numerical class refers to its rowing arrangement rather than stacked decks. Roman service likely included septiremes and octeres, with possible nine-class vessels appearing in accounts of the Actium fleets. The accounts of octeres discussed here center on Actium. Evidence becomes uncertain as the numbers rise, and the designs quickly approach practical limits.