The new LNG tugs have been developed by Washburn & Doughty Associates Inc. of East Boothbay in the state of Maine.
The shipbuilder specializes in building steel and aluminium vessels from 40-feet to 200-feet.
International classification society, the American Bureau of Shipping, said the new vessel is classed ABS A1, AMS as a towing vessel, Class 1 fire-fighting and as an escort vessel.
The Z-drive tractor tugs have power ratings of up to 6,000 horsepower. One of their stand-out features is a deluge fire-fighting system in which the vessel protects itself and the crew against fire by enveloping itself in water.
On of the tugs, the April Moran, is currently assisting LNG carriers at the Elba Island LNG terminal in Georgia.
ABS said the firefighting-1 classification requires two monitors to each produce 5,280 gallons per minute over a distance of 394 feet at a height of 148 feet, as well as a deluge system and the ability to sustain fire-fighting operations for a minimum of 24 consecutive hours.