Built in 1998, by Thoma-Sea Boatbuilders of Houma, Louisiana (hull #109) as the Dumar I for Dolphin Marine of Golden Meadow, Louisiana.
The tug was later renamed by Dolphin Marine as the the Dolphin I.
The tug was eventually acquired by Harvey Gulf International Marine of New Orleans, Louisiana where she was renamed as the Harvey Lightning.
Powered by two EMD-16-710-G7A Turbo diesel engines (with both Keel and Grid Cooling) with Lufkin 14216 reduction gears at a ratio of 4.23:1, turning two 122(in) by 120(in), four bladed, fixed pitch, stainless steel propellers mounted in Kort Nozzles for a rated 14,500 horsepower.
Her electrical service is provided by two 99kW LIMA generators driven by two GM 8v71 engines. The tugs capacities are 200,000 gallons of fuel oil, 6,000 gallons of engine oil, and 27,000 gallons of potable water.
The towing gear consists of an INTERcon DW225 towing winch, powered by a dedicated GM 8v71 engine. As well as a Nordic hydralic towing pin system, a Green Marine telescoping boom crane.
However, in 2014 Harvey Gulf's tug division was acquired by the Signet Maritime Corporation of Houston, Texas. Where the tug was renamed as the Signet Lightning.