CAM ships were World War II-era British merchant ships used in convoys as an emergency stop-gap until sufficient escort carriers became available. CAM ship is an acronym for catapult aircraft merchant ship. A CAM ship was equipped with a rocket-propelled catapult launching a single Hawker Hurricane, dubbed a "Hurricat" or "Catafighter". CAM ships continued to carry their normal cargoes after conversion.
After the Fall of France in June 1940, long range German Focke-Wulf Fw 200 reconnaissance aircraft of I/KG40 shadowed and bombed merchant shipping from the French airfield at Bordeaux-Merignac. The Admiralty had already experimented with fighter catapult ships - converted freighters, equipped with a single rocket-launched fighter, manned by naval crews. They ordered 50 more rocket-propelled catapults for fitting aboard merchant ships. These were equipped with fifty Hawker Hurricane Mark I aircraft, converted to Sea Hurricane IAs as a temporary measure to provide fighter protection beyond the range of bases on the British Isles. The ship was not fitted for aircraft recovery, so, unless close to land, the pilot would bail out or ditch in the sea at the end of the flight and the plane would be lost.
The RAF formed the Merchant Ship Fighter Unit (MSFU) on 5 May 1941 in RAF Speke by the River Mersey in Liverpool. Wing Commander E.S. Moulton-Barrett commanded the unit providing training for volunteer pilots, Fighter Direction Officers (FDOs) and airmen. After training, MSFU crews were posted to Liverpool, Glasgow or Avonmouth where they assisted in loading their Hurricanes onto the catapults. Each team consisted of one pilot for Atlantic runs (or two pilots for voyages to Russia, Gibraltar or the Mediterranean Sea) with one fitter, one rigger, one radio-telephone operator, one FDO and a seaman torpedoman who worked on the catapult as an electrician.
MSFU crews signed ships articles as civilian crew members under the authority of the civilian ship's master. The ship's chief engineer became responsible for the catapult and the first mate acted as Catapult Duty Officer (CDO) responsible for firing the catapult when directed. The single Hurricane fighter was launched only when enemy aircraft were sighted and agreement was reached via hand and flag signals between the pilot, CDO and ship's master.
The first CAM ship, Michael E, was sponsored by the Royal Navy while the RAF MSFUs were working up. After a trial launch off Belfast, Michael E sailed with convoy OB 327 on 28 May 1941. She was sunk by U-108 on 2 June. The first RAF trial CAM launch was from Empire Rainbow at Greenock on the River Clyde on 31 May 1941, the Hurricane landed at Abbotsinch. Six CAM ships joined convoys in June 1941. When a CAM ship arrived at its destination, the pilot usually launched and landed at a nearby airfield to get in as much flight time as possible before his return trip. Pilots were rotated out of CAM assignments after two round-trip voyages to avoid the deterioration of flying skills from the lack of flying time during the assignment.
CAM sailings were initially limited to North American convoys with aircraft maintenance performed by the Royal Canadian Air Force at Dartmouth, Nova Scotia. CAM ships sailed on Gibraltar and Freetown convoys beginning in September, 1941, after an aircraft maintenance unit was established at the RAF base at North Front, Gibraltar. No CAM aircraft were provided during January and February 1942 after it proved impossible to maintain the catapult-mounted aircraft in flying order during the North Atlantic winter. CAM sailings resumed on 6 March 1942 on North Atlantic convoys and in April on the Arctic Russian convoys with a RAF aircraft maintenance unit in Archangelsk.
27 CAM ships were Ministry of War Transport owned Empire ships, ten of which were sunk: Empire Burton (sunk), Empire Clive, Empire Darwin, Empire Day, Empire Dell (sunk), Empire Eve (sunk), Empire Faith, Empire Flame, Empire Foam, Empire Franklin, Empire Gale, Empire Heath, Empire Hudson (sunk), Empire Lawrence (sunk), Empire Moon, Empire Morn, Empire Ocean, Empire Rainbow (sunk), Empire Ray, Empire Rowan (sunk), Empire Shackleton (sunk), Empire Spray, Empire Spring (sunk), Empire Stanley, Empire Sun, Empire Tide, Empire Wave (sunk).
- The trolley receiving bar was removed at dawn.
- The airmen started the aircraft and warmed up the engine at intervals.
- The pilot climbed into the aircraft when enemy aircraft were reported.
- The ship hoisted the international flag code F when the decision was made to launch. (CAM ships were usually stationed at the head of the outboard port column of a convoy so they could manoeuvre into the wind for launch.)
- An airman removed the pins, showed them to the pilot, and took them to the CDO.
- The pilot applied 30 degree flaps and 1/3 right rudder.
- The CDO raised a blue flag above his head to inform the ship's master of his readiness to launch.
- The ship's master manoeuvred the ship into the wind and raised a blue flag above his head to authorise the launch. (The ship's master stood on the starboard bridge wing to avoid the catapult rocket blast which sometimes damaged the port side of the bridge.)
- The CDO waved his blue flag indicating he was ready to launch upon a signal from the pilot.
- The pilot opened full throttle, tightened the throttle friction nut, pressed his head back into the head-rest, pressed his right elbow tightly against his hip, and lowered his left hand as a signal to launch.
- The CDO counted to three, waited for the bow to rise from the trough of a swell, and moved the switch to fire the catapult rockets.
CAM combat launches
|1 Nov 41||SS Empire Foam||Flying Officer Varley||Focke-Wulf Fw 200 chased off; pilot recovered by HMS Broke.|
|26 Apr 42||SS Empire Morn / QP 12||FO Kendal||Blohm & Voss BV 138 chased off & Junkers Ju 88 shot down; pilot died from injuries received while bailing out.|
|26 May 42||SS Empire Lawrence / PQ 16||PO Hay||Two Heinkel He 111s shot down; Hurricane shot down, pilot recovered by HMS Volunteer.|
|14 Jun 42||SS Empire Moon / HG 84||PO Sanders||Focke-Wulf Fw 200 chased off; pilot recovered by HMS Stork.|
|18 Sep 42||SS Empire Morn||FO Burr||Two Heinkel He 111s destroyed; pilot flew to the Russian Keg Ostrov aerodrome.|
|1 Nov 42||SS Empire Heath / HG 91||FO Taylor||Focke-Wulf Fw 200 shot down; pilot nearly drowned before recovery.|
|28 Jul 43||SS Empire Darwin / SL 133||FO Stewart||Focke-Wulf Fw 200 destroyed; pilot recovered by HMS Leith.|
|28 Jul 43||MV Empire Tide / SL 133||FO Flynn||Focke-Wulf Fw 200 destroyed; pilot recovered by HMS Enchantress.|
In total, there were nine combat launches, eight aircraft and one pilot were lost for eight German aircraft destroyed and one damaged.
As adequate numbers of escort carriers became available, CAM sailings on North American and Arctic Russian convoys were discontinued in August 1942. The aircraft maintenance unit was withdrawn from Archangel in September 1942. Catapults were removed from ten of the 26 surviving CAM ships while the remaining 16 continued to sail with the Mediterranean and Freetown convoys. Headquarters RAF Fighter Command ordered all MSFUs to be disbanded commencing 8 June 1943. The combat launches from homeward bound convoy SL 133 were from the last two operational CAM ships to sail, the last MSFU was disbanded 7 September 1943. Twelve of the 35 CAM ships had been sunk while sailing on 170 round trip voyages. Two more ships, Cape Clear and City of Johannesburg, were briefly fitted with dummy catapults and aircraft for deception purposes in late 1941.
- Wise, pp. 70–77
- Hague, p.78
- Mitchell and Sawyer
- Hague, p. 79
- Barker, Ralph (1978). The Hurricats. London: Pelham Books. ISBN 0-7207-0994-6.
- Hague, Arnold (2000). The Allied Convoy System 1939-1945. Naval Institute Press. ISBN 1-55750-019-3.
- Mitchell, W H, and Sawyer, L A (1990). The Empire Ships. London, New York, Hamburg, Hong Kong: Lloyd's of London Press Ltd. ISBN 1-85044-275-4.
- Wise, James E. Jr. (1974). "Catapult Off - Parachute Back". United States Naval Institute Proceedings.