The third USS Canonicus (YT-187) was a United States Navy harbor tug which entered service in 1941 and was discarded in 1947.

History
United States
Name	USS Canonicus
Namesake	Canonicus (c. 1565-1647), a Native American chief of the Narragansett
Launched	1941
Acquired	1 May 1941
Decommissioned	30 April 1947
In service	3 June 1941
Fate	Transferred to the Maritime Commission for disposal 30 April 1947
General characteristics
Type	Harbor tug
Displacement	133 tons
Length	93 ft (28 m)
Beam	22 ft (6.7 m)
Propulsion	Diesel-electric 750 hp (560 kW), single propeller

It was built in Beaumont, Texas as the Thomas E. Moran for the Moran Towing Co., and purchased from them by the navy on 1 May 1941. Renamed Canonicus, it was placed in service on 3 June 1941. It served in the 1st Naval District and 5th Naval District.

Canonicus was transferred to the Maritime Commission for disposal on 30 April 1947, and was repurchased by Moran Towing, becoming the Mary Moran. It ultimate fate is unknown.