1943Schooner Gertrude L Thebaud was assigned anti-submarine patrol and sailed a sector from Gloucester to Cashes Shoals.Economy and Industry, Government and Public Service, Maritime & Fishing Industry, Military

Large schooners patrolled up to one hundred miles offshore. Sailing patrol craft were particularly hazardous for German U-boats which normally relied on warning impulses from vibrating propellers of approaching vessels.
Eldridge, David S."Gloucester FIshing in World War II," The American Neptune, Col. XXVII, No. 3, July 1967.