The vessel carries 420.00 m3 (92,390 imp gal) of diesel fuel giving the ship a range of 10,000 nmi (19,000 km) at 12 knots (22 km/h) and allowing Leonard J. Cowley to stay at sea for up to 35 days.

[4] The ship is equipped with an autopilot including adaptive steering gear, a shilling rudder and a 250-horsepower (190 kW) bow thruster for maneuvering.

[4] Leonard J. Cowley has a computer system which identifies exact locations of other vessels, and two radars, one of which has a feed to the electronic charting unit.

[2] Leonard J. Cowley monitors fishing activities to fulfill Canada's commitment to the Northwest Atlantic Fisheries Organization.

[4] Due to the nature of the vessel's duties in fisheries enforcement, Leonard J. Cowley often carries an armed boarding team.

[4] While Leonard J. Cowley's primary task is fisheries patrol, the vessel also carries out search and rescue operations.

[4] The ship was constructed by West Coast Manly Shipyard in Vancouver, British Columbia with the yard number 590.

[1][2] The ship was named for Len Cowley, a Newfoundland biologist who served with the Department of Fisheries and Oceans as assistant deputy minister.

[2] On 11 August 1986, Leonard J. Cowley brought 155 Tamil refugees into St. John's after they had been set adrift in lifeboats from a smuggler's boat of the coast of Newfoundland.