Charles Axel Alexius Modeer, born 1877, was a native of Kalmar, Sweden, and moved to Chicago with his family when he was a baby. Following in the seafaring footsteps of his father, who was a shipmaster on the Great Lakes, Modeer ran away from home at age 17 and spent six years aboard sailing ships. He joined the Pacific Mail Steamship Company out of San Francisco after 1900, rising from fourth officer to first officer. On December 31, 1906, while Modeer was serving as second officer on the SS City of Panama, he and two others rescued three men who were swept overboard. He received a gold medal for bravery from President Theodore Roosevelt.

Modeer entered the U.S. Lighthouse Service on February 19, 1909, as second officer on the lightship Columbia, and served on various lighthouse tenders, including the Manzanita. He commanded the Manzanita from 1929 through 1941, when he retired from the Coast Guard. He was headquartered at Astoria, Oregon. During World War I, Modeer joined the Navy and commanded the former lighthouse tender Rose after it was put into service as a Naval patrol vessel in 1917. Before leaving the Navy, he commanded a cargo ship, the West Compo, for one tour of duty in 1919. Modeer then returned to the Lighthouse Service, which was absorbed by the Coast Guard in 1939.