Built in 1973, by McDermott Shipyard Incorporated of Morgan City, Louisiana (hull #181) as the Ocean Sun for L and L Marine Services Incorporated of St. Louis, Missouri. A subsidiary of the Apex Oil Company of St. Louis, Missouri.
In 1988, the tug was acquired by the Morania Oil Tanker Corporation of Staten Island, New York. Where she was renamed as the Morania No. 3.
In 1994, she was acquired by Penn Maritime Incorporated of Stamford, Connecticut. Where she was renamed the tug as the Dolphin.
In 2000, the Morania Oil Tanker Corporation merged with Penn Maritime Incorporated of Stamford, Connecticut. Where the tug retained her name.
In 2012, Penn Maritime Incorporated was acquired by the Kirby Corporation of Channelview, Texas. Where the tug retained her name.
In 2017, the tug was phased out of active service. And, she was "laid up," at the Kirby Corporation's yard in Philadelphia, Pennsylvania.
In 2018, she was acquired by the Curtin Maritime Company of Long Beach, California. Where the tug was renamed as the Karen C.
Powered by two, twelve cylinder, EMD 12-645-E5 diesel engines. With Falk reduction gears, at a ratio of 3.958:1. Turning two, cast steel, fixed pitch propellers, mounted in kort nozzles. She is a twin screw tug, rated at 4,300 horsepower.
Her electrical service is provided by two, 99kW, John Deere 6068 generator set. The tug's capacities are 120,727 gallons of fuel, 4,100 gallons of lube oil, and 11,000 gallons of water.
The towing equipment consists of a double drum, Markey TDSD-32 towing winch. Outfitted with 2,000(ft) of 2(in) towing wire on the port drum and 2,000(ft) of 2(in) towing wire on the starboard drum,