HMCS St. Eloi was one of twelve Battle class naval trawlers used by the Royal Canadian Navy (RCN). Named after the Action of the St. Eloi Craters, she was built by Polson Iron Works, in Toronto, Ontario, and was commissioned on 13 November 1917. Decommissioned in 1920, she was turned over to the Department of Marine and Fisheries, and like sister ships HMCS Messines, HMCS St. Julien, and HMCS Vimy was converted to a lightship, eventually being designated Lightship No.