The design of the Spearhead-class expeditionary fast transport is 70 percent in common with the Hawaii Superferries, both built by Austal USA.
USNS Guam was built as Huakai, whose name is based on the Hawaiian language word huakaʻi, which means "journey". The vessel is a 373-foot (114 m) long high-speed roll-on/roll-off (Ro/Ro) passenger ship. The vessel was originally built for Hawaii Superferry, and has a capacity of 866 passengers and up to 282 subcompact cars. It is 19 feet (5.8 m) longer than its sister ship, USNS Puerto Rico, due to a bi-fold ramp installed on the stern of the ship.
The vessel featured environmentally friendly technologies including non-toxic bottom paint, zero wastewater discharge and clean diesel engines.
According to wikipedia