The USCGC Spar (WLB-403) was a 180 feet (55 m) sea going buoy tender

USCG Seagoing Buoy Tender

The Seagoing Buoy Tender is a type of U.S. Coast Guard cutter originally designed to service aids to navigation, throughout the waters of the United States, and wherever U.S. shipping interests require. The Coast Guard has maintained a fleet of seagoing buoy tenders dating back to its origins in...

. An Iris class vessel, she was built by Marine Ironworks and Shipbuilding Corporation in Duluth, Minnesota

Duluth, Minnesota

Duluth is a port city in the U.S. state of Minnesota and is the county seat of Saint Louis County. The fourth largest city in Minnesota, Duluth had a total population of 86,265 in the 2010 census. Duluth is also the second largest city that is located on Lake Superior after Thunder Bay, Ontario,...

. Spar's preliminary design was completed by the United States Lighthouse Service

United States Lighthouse Service

The United States Lighthouse Service, also known as the Bureau of Lighthouses, was the agency of the US Federal Government that was responsible for the upkeep and maintenance of all lighthouses in the United States from the time of its creation in 1910 until 1939...

 and the final design was produced by Marine Iron and Shipbuilding Corporation in Duluth. On 13 September 1943 the keel was laid, she was launched on 2 November 1942 and commissioned on 12 June 1944.