thumb|, formerly Empire ActivityMerchant aircraft carriers (MAC) were bulk cargo ships with minimal aircraft handling facilities, used during
World War II by
Britain and the
Netherlands as an interim measure to supplement British and
United States-built
escort carriers in providing an anti-submarine function for convoys. The original intention had been that they would be an interim measure preceding the wider introduction of escort carriers.
Gestation
The idea of simple adaptations of bulk cargo ships for aircraft had been considered by the
Admiralty for some time. It would provide desperately needed air cover for convoys without losing valuable cargo capacity. There was, however, resistance to the concept arising from several technical issues; the 12 knot speed was considered too slow for aircraft operation, the design and development time was expected to take too long and aircraft movements on steel decks over highly flammable fuel cargoes was considered too dangerous.
The then Director of Merchant Shipbuilding,
Sir James Lithgow, made a rough design on the back of an envelope and offered to adapt two ships about to be built at his family's shipyard. This was on condition that "I am not interfered with by the Admiralty". Work started in June 1942 on two grain carriers,
Empire MacAlpine and
Empire MacAndrew. Ten more were ordered by October and a total of thirty-two were planned (cut back to nineteen with the delivery of escort carriers).
Ship details
The Merchant Aircraft Carriers were modified bulk grain carriers or tankers built with flight decks and small island structures. Minimal aircraft handling and accommodation facilities were available. The bulk nature of the cargoes did not need deck mounted cargo-handling gear used for general cargoes. They operated with civilian crews, under merchant colours, and carried their regular cargo in addition to operating aircraft. Their
Fairey Swordfish aircraft carried out anti-submarine patrols around the convoy.
The scale of the conversion was small, hence it could be completed in a short time; five months has been quoted as being typical.
The tanker conversions had no hangar and carried four
Fairey Swordfish on deck; the grain ships also carried four aircraft but had a small hangar with a hoist. Flight decks were around long on the tankers and between 413 and 424 feet for the grain ships, width was in all cases. Aircrew accommodation was minimal and ammunition and fuel stores were neither armoured nor partitioned.
Many of the ships were given names with the prefix "Mac-", in a reference to their designation as MACs; the "Empire" prefix was used on ships built by the
Ministry of War Transport to distinguish them from pre-war privately owned ships. Since these ships were owned by the Government and only on loan to the shipping companies it was easier to take them out of service for conversion.
Air Party
The 'Air Party' was the Fleet Air Arm personnel who flew and supported the aircraft, but was under the nominal authority of the merchant ship's commander. It consisted of an Air Staff Officer (Lt-Commander), the aircrew, a
doctor, a batsman (
landing control officer), ten ship's gunners, four signalmen, and three or four
Able Seamen. The
Merchant Navy part of the crew might have an extra
mate and/or
wireless operator but was otherwise unchanged and operated under Merchant Navy conditions.
The aircrew on each ship formed one
flight of the MAC-ship Wing which consisted of
836 and
860 Naval Air Squadrons, based at
HMS Shrike,
RNAS Maydown, near
Derry in
Northern Ireland. 836 was manned by the Royal Navy and
860 (Dutch) Squadron was manned by Dutch personnel and assigned to the two Dutch MACs.
An informal, illegal benefit for aircrews was their ability to smuggle contraband without paying import duties. Aircraft were flown off to RNAS Maydown laden with goods which were usually unloaded and hidden before
HM Customs could intervene.
Aircraft
Fairey Swordfish at an airshow in 1988. This aircraft was assigned to 'L' Flight of 836 Squadron on board the MAC ship Rapana during World War II
Two aircraft types were considered for use on MAC ships: the Swordfish and the
Vought SB2U Vindicator (known in British service as the "Chesapeake"). Fifty Chesapeakes were delivered, but after a three month trial, they were deemed unsuitable by the Admiralty and relegated to a training role.
In practice, the MAC ships were successful. The apparently antiquated, but robust, Swordfish aircraft were suited to the conditions and their patrols were very effective. Flying more than 4,000 sorties in all, wartime records show that no convoy with an accompanying MAC ship ever lost a vessel to U-boats, nor was any MAC ship lost
.
Ships
Empire class grain carriers
8,000 tons, 12 knots, 4 aircraft, crew 107, launched December 1942-January 1944. Equipped with hangar and lift. Armament: 1 x 4 in (102mm), 2 x 40 mm, 4 x 20 mm guns.
[ ] Empire class oil tankers
9,000 tons, 12 knots, 4 aircraft, crew c.110, launched May-July 1943. No hangar and lift; aircraft maintained and stored on deck. Armament: 1 x 4 in (102 mm), 8 x 20 mm guns.
[ ] Rapana class oil tankers
12,000 tons, 12 knots, 4 aircraft, crew c.100, converted 1942-44. Anglo-Saxon Petroleum Company tankers. No hangar and lift; aircraft maintained and stored on deck. Armament: 1 x 4 in (102 mm), 8 x 20 mm guns.
[ ]- MV Ancylus: operated Swordfish Mk 2 from ‘O’ Flight of 860 (Dutch) squadron
- MV Gadila: operated under the Dutch ensign, with Fairey Swordfish of 'S' flight, 860 (Dutch) Squadron and of 861 (Dutch) Squadron
- MV Macoma: operated under the Dutch ensign with Fairey Swordfish of 860 (Dutch) Squadron
- MV Rapana: operated Swordfish Mk 2 from ‘L’ Flight of 836 Squadron
See also
