Hellespont-class

From Star Trek: Gamma One

The Hellespont-class Escort is a short-range gunship deployed as of the early 2260s with small 40-60 man crews specifically to do guard and rescue duty for Merchant Marine and civilian convoys. A lot of these are deployed along 'hard' borders with the Klingons to pull secondary duty as recon ships when not actively guarding convoys -- when they notice Klingon fleet or wing movements, or suspicious activity on border planets which indicate the Klingons staking a claim that the UFP might want to dispute, they then call in the bigger ships for extended diplomatic or military action.