The USS Fort McHenry can fill tanks and settle at the back to flood rear interior decks through operating doors in the stern. Landing craft then use the interior hold as a dock and emerge to ferry equipment and supplies ashore. (Photo courtesy of U.S. Navy)

Fifty Seabees from Naval Mobile Construction Battalion (NMCB) 40, forward deployed to Camp Shields, Okinawa, Japan, have shipped out to the tsunami-ravaged shores of Indonesia to assist with initial disaster recovery efforts, their command reported Jan. 6. An additional 300 are preparing to follow, as missions require. They will serve in the relief effort along with Marines from the 3rd Marine Division, and sailors from 7th Fleet.

The initial wave of Seabees will focus on contingency construction, such as road clearing and runway repairs, while the sailors they accompany aboard USS Fort McHenry, an LSD class vessel, will use water purification equipment aboard ship to supply clean water for victims of the disaster.

Depending upon how the situation unfolds, the Seabees may establish an on-shore base camp. The detachment carries enough fuel, medical supplies, road clearing and electrical power generating equipment, among other necessities, to be largely self-sustaining if they deploy ashore, although they will be supported with food and water provided by the Fort McHenry.

The LSD is a type of ship conceived during World War 2 as a craft that could sail to the site of an amphibious landing, carry and launch assault boats directly from a well-deck in the rear of the vessel. To do this, the ship floods several tanks in the stern and ballasts the ship down. This floods the deck, which allows the landing craft stored aboard to come and go from the hold.