Built by Hugh Barclay of Ardrossan, Mary Sinclair was already forty-two years old when she enjoyed her brief moment of fame in 1918. Becalmed off Littlehampton in the company of the Mary Ann Mandall, another schooner, they were surprised when early in the morning a U-Boat surfaced at a distance of about 100 yards. Riflemen emerged on the conning tower and started taking pot shots. Both responded instantly with a combination of three and twelve pounder guns forcing a retreat. Re-emerging at a safer distance, the U-Boat opened fire with a large deck cannon eventually causing severe damage, but not before over sixty shells had been sent in reply in an action lasting over an hour. Envisageing imminent capture, they were saved when an armed trawler hearing the battle raced to the scene and forced the U-Boats withdrawal. The Mary Sinclair was last recorded, still in use, in 1938.