Frigate

From WikiPOBia

A frigate was a 5th or 6th rate ship, carrying between about 28 and 44 cannon on one deck. Frigates were generally fast sailors but too lightly armed to sail in the line of battle. Their principal functions were for scouting for the fleet and attacking enemy shipping. They were also used for carrying important people on missions.

Because of their relative independence, frigate captains were often able to enrich themselves significantly by prize money and a frigate captaincy was often a stepping stone to more important posts.