The word Rus, in former times wrongly connected with the tribal name Rhoxolani, is more probably derived from Ruotsi, a Finnish name for the Swedes, which seems to be a corruption of the Swedish rothsmenn, " rowers " or " seafarers."
In time of war they served as light-armed troops or as rowers in the fleet; from the Peloponnesian War onwards they were occasionally employed as heavy infantry (61rXZr at), distinguished bravery being rewarded by emancipation.
When a naval battle was in progress, it would depend for its manoeuvring on the rowers.
The rowers in each vessel, though among the northern folk these were free men and warriors, not slaves as in the Roman and Carthaginian galleys, would yet need to be supplemented by a contingent of fighting men, marines, in addition to their crew.
In saga literature we read of craft (of " long ships ") with 20 to 30 benches of rowers, which would mean 40 to 60 oars.