Thomas C. Gillmer (1911–2009) was a naval architect and the author of books about modern and historical naval architecture. He was born in Warren, Ohio on July 17, 1911.

At his family's summer cottage near Lake Erie in Ohio, he learned to sail a 14-foot sloop by himself. He graduated from Warren High School, then attended the U.S. Naval Academy.^[1]

After graduating from the U.S. Naval Academy in 1935, he served aboard the light cruisers USS Raleigh (CL-7) and USS Savannah (CL-42) in the Pacific and Mediterranean.^[1]

In 1941, he joined the Marine Engineering Department at the Naval Academy. During World War II, he served as an instructor of Ship Construction and Damage Control at the U.S. Naval Academy. He resigned his commission with the Navy in 1946 to join the Academy's faculty as a professor and became chairman of the First Class Committee of the Marine Engineering department. (Note: The Marine Engineering Department became the Division of Engineering and Weapons in 1970 which contained the Naval Systems Engineering Department. Naval Systems later became the current Naval Architecture and Ocean Engineering Department.) During the 1950s, Professor Gillmer established the Ship Hydromechanics Laboratory in Isherwood Hall which consisted of an 85' × 6' × 4' towing tank, an 18' × 22' × 4' intact and damaged stability demonstration tank and a small circulating water channel.

After retiring from the Naval Academy in 1967, Gillmer continued living in Annapolis, where he pursued a career as the architect of sailing vessels and an author on the subject. In 1969, he established the engineering firm Thomas Gillmer, Naval Architect, Inc. in Annapolis.^[1] His designs included modern yachts and replicas of historic sailing ships.^[2] He worked with artist Melbourne Smith on the design of the Pride of Baltimore in 1976, the Pride of Baltimore II in 1986, and the Kalmar Nyckel in 1997, and brought Capt.Iver Franzen into his firm in 1986 to assist with the latter two projects, among others.^[3] The Navy hired Gillmer and Franzen to evaluate the condition of the USS Constitution prior to the vessel's restoration in 1997.^[1]

The Allied Seawind Ketch, designed by Gillmer in 1962, was the first fiberglass-hulled yacht to circumnavigate the Earth.^[4]

Gillmer designed and built his own house in Annapolis in 1947, where he lived for more than 60 years. He was married for 62 years to the former Anna Derge. After her death in 1999, he married Ruth Newsome, who was his wife until he died on December 16, 2009.^[1][5]