While in the gulf, she took brigantine East, suspected of communicating with Confederate-held shore territory, and towed damaged Parkersburg from Pensacola, Florida to Key West.

Ordered to Fortress Monroe, Virginia, 3 July, Mount Vernon gave refuge to Unionists preparing to travel north.

On 1 September she sailed for Mobjack Bay to relieve USS Daylight, and in November proceeded to Beaufort, North Carolina.

She engaged British schooner Phantom off Cape Lookout 2 December, and on the 31st sent an armed party to aid in firing a ship being used by the Confederates as a beacon.

She was in the group of Union ships attacked by North Carolina off the mouth of Cape Fear River in May, and she searched for Florida in July.