Commercial steamship, SS Mormaccove of the Suisun Bay Reserve Fleet. She served in the commercial trade industry for almost 20 years (1961-1980) before being acquired by the Navy and converted for Naval use. At that time her name was changed to USNS Northern Light. She was used by the Navy for 5 years, then placed in the Mothball Fleet in RRF-30 status, meaning she could be ready for deployment in 30 days. In 2000, she was removed from Ready Reserve staus, handed over to MARAD and is now slated for dismantling.
These valves in "shaft alley" of USNS Northern Light, a commercial breakbulk steamship, controlled water flow into the propeller shaft to keep it cool.
"Breakbulk ships" were characterized by large open hatches and fitted with boom-and-winch gear or deck cranes and primarily used in ports. USNS Northern Light, originally known as SS Mormacbay, served in the commercial trade industry from 1961 until 1980, when she was acquired by the Navy and eventually moved to Suisun Bay.