Merchant aircraft carrier
Encyclopedia
Merchant aircraft carriers (MAC) were bulk cargo ships with minimal aircraft handling facilities, used during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
by Britain
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
and the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
as an interim measure to supplement British and United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
-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 AdmiraltyAdmiralty
The Admiralty was formerly the authority in the Kingdom of England, and later in the United Kingdom, responsible for the command of the Royal Navy...
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. The MAC-ships were manned by a Merchant Navy crew, under merchant colours, the Royal NavyRoyal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
provided the air department and the guns were manned by DEMS
Dems
DEMS may refer to:*Democratic Party *Deepika English Medium School*Defensively Equipped Merchant Ships...
soldiers. They carried their regular cargo in addition to operating aircraft. Tanker MAC-ships were able to carry about 80 percent of their original cargo, the remaining space being taken for Avgas
Avgas
Avgas is an aviation fuel used to power piston-engine aircraft. Avgas is distinguished from mogas , which is the everyday gasoline used in cars and some non-commercial light aircraft...
stowage to Admiralty safety standards. Grain carrier MAC-ships suffered a reduction of about 3,000 tons (or 30 per cent) of the original cargo of grain. Their Fairey Swordfish
Fairey Swordfish
The Fairey Swordfish was a torpedo bomber built by the Fairey Aviation Company and used by the Fleet Air Arm of the Royal Navy during the Second World War...
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 fuel piping arrangements in a tanker made it impossible to build a hangar under the flight deck, so tanker conversions were limited to embarking three Fairey Swordfish
Fairey Swordfish
The Fairey Swordfish was a torpedo bomber built by the Fairey Aviation Company and used by the Fleet Air Arm of the Royal Navy during the Second World War...
which had to be kept on deck. Collapsible deck-edge wind breaks were fitted on the flight deck aft to provide some protection for parked aircraft. The grain carriers had a small hangar aft with a single lift which allowed the carriage of four Swordfish. Flight decks were around 460 feet (140.2 m) long on the tankers and between 413 and 424 feet for the grain ships, width was 62 feet (18.9 m) in all cases. All the MAC-ships were fitted with four arrester wires. The permanent deck park of the tanker MAC-ships required a barrier for aircraft recovery. 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
Empire ship
The Empire ships were a series of ships in the service of the British Government. Their names were all prefixed with "Empire". Mostly they were used during World War II by the Ministry of War Transport , who owned the ships but contracted out their management to various shipping lines. Some ships...
" 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 ArmFleet Air Arm
The Fleet Air Arm is the branch of the British Royal Navy responsible for the operation of naval aircraft. The Fleet Air Arm currently operates the AgustaWestland Merlin, Westland Sea King and Westland Lynx helicopters...
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
Landing signal officer
Landing Signal Officers are naval aviators specially trained to facilitate the "safe and expeditious recovery" of naval aircraft aboard aircraft carriers. Originally LSOs were responsible for bringing aircraft aboard ship using hand signals...
), ten ship's gunners, four signalmen, and three or four Able Seamen
Able Seaman (rank)
In the British Royal Navy in the middle of the 18th century, the term able seaman referred to a seaman with at least two years' experience at sea...
. 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
Flight (military unit)
A flight is a military unit in an air force, naval air service, or army air corps. It usually comprises three to six aircraft, with their aircrews and ground staff; or, in the case of a non-flying ground flight, no aircraft and a roughly equivalent number of support personnel. In most usages,...
of the MAC-ship Wing which consisted of 836 and 860 Naval Air Squadrons, based at HMS Shrike, RNAS Maydown, near Derry
Derry
Derry or Londonderry is the second-biggest city in Northern Ireland and the fourth-biggest city on the island of Ireland. The name Derry is an anglicisation of the Irish name Doire or Doire Cholmcille meaning "oak-wood of Colmcille"...
in Northern Ireland
Northern Ireland
Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...
. 836 NAS was manned by the Royal Navy and 860 NAS was manned by Dutch personnel and assigned to the two Dutch MAC-ships.
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
Vought
Vought is the name of several related aerospace firms. These have included, in the past, Lewis and Vought Corporation, Chance Vought, Vought Sikorsky, LTV Aerospace , Vought Aircraft Companies, and the current Vought Aircraft Industries. The first incarnation of Vought was established by Chance M...
SB2U Vindicator
SB2U Vindicator
The Vought SB2U Vindicator was a carrier-based dive bomber developed for the United States Navy in the 1930s, the first monoplane in this role. Obsolescent at the outbreak of World War II, Vindicators still remained in service at the time of the Battle of Midway, but by 1943, all had been withdrawn...
(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.
However, there is evidence that Sea Hurricanes were deployed aboard MAC ships. The FleetAirArm web site states:
www.fleetairarmarchive.net/aircraft/seahurricane.htm
"The Sea Hurricane Mk I were followed by about 300 Mk Is converted to Sea Hurricane Mk IB configuration, these having catapult spools plus a V-frame arrester hook: in addition 25 Mk IIA were modified as Sea Hurricane IB or Hooked Hurricane II fighters. Their initial role was a considerable improvement on CAM-ship deployment, for from October 1941 they began to go to sea aboard MAC-ships, these being large Merchant ships fitted with a small flight deck."
NB. This date of October 1941 is inconsistent with the first MAC ship becoming operational in early 1943, and the same article also says "by 1943 the Sea Hurricane had all but disappeared from service". This is probably the author getting confused between MAC ships and Escort Carriers, a common mistake.
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. They flew 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.
Empire class grain carriers
Approximately 8,000 tons deep load, 12 knots, 4 aircraft, crew 107, launched December 1942-January 1944. Equipped with hangar and lift. Armament: 1 x single 4 in (102 mm) QF MK IV, 2 x single 40 mm Bofors, 4 x single 20 mm Oerlikon cannons.- MV Empire MacAlpineMV Empire MacAlpineMV Empire MacAlpine was a grain ship converted to become the first Merchant Aircraft Carrier .MV Empire MacAlpine was built at the Burntisland Shipbuilding Co Ltd, Burntisland, Scotland, under order from the Ministry of War Transport and was delivered on 14 April 1943...
- MV Empire MacAndrewMV Empire MacAndrewMV Empire MacAndrew was a grain ship converted to become a Merchant Aircraft Carrier or MAC ship.MV Empire MacKendrick was built at William Denny and Brothers Dumbarton Scotland under order from the Ministry of War Transport...
- MV Empire MacCallumMV Empire MacCallumMV Empire MacCallum was a grain ship converted to become a Merchant Aircraft Carrier or MAC ship.MV Empire MacCallum was built at Lithgows shipyard, Glasgow, Scotland, under order from the Ministry of War Transport. As a MAC ship, only her air crew and the necessary maintenance staff were naval...
- MV Empire MacDermottMV Empire MacDermottMV Empire MacDermott was a bulk grain ship built as a Merchant Aircraft Carrier . She served with the British Merchant Navy during the Second World War, with rudimentary aircraft handling facilities operated by a Fleet Air Arm "air party"....
- MV Empire MacKendrickMV Empire MacKendrickMV Empire MacKendrick was a grain ship converted to become a Merchant Aircraft Carrier or MAC ship.She was built by the Burntisland Shipbuilding Company Ltd, Fife, Scotland, under order from the Ministry of War Transport and was delivered on 12 December 1943...
- MV Empire MacRaeMV Empire MacRaeMV Empire MacRae was a grain ship converted to become a Merchant Aircraft Carrier or MAC ship.MV Empire MacRae was built at Lithgows shipyard, Glasgow, Scotland, under order from the Ministry of War Transport...
Empire class oil tankers
Approximately 9,000 tons deep load, 11 knots, 3 aircraft, crew 122, launched May–July 1943. BPBP
BP p.l.c. is a global oil and gas company headquartered in London, United Kingdom. It is the third-largest energy company and fourth-largest company in the world measured by revenues and one of the six oil and gas "supermajors"...
tankers. No hangar and lift; aircraft maintained and stored on deck. Armament: 1 x single 4 in (102 mm) QF MK IV, 8 x single 20 mm Oerlikon cannons.
- MV Empire MacCabeMV Empire MacCabeMV Empire MacCabe was an oil tanker converted to a merchant aircraft carrier or MAC ship.MV Empire MacCabe was built by Swan Hunter, Wallsend under order from the Ministry of War Transport. She entered service as a MAC ship in December 1943, however only her air crew and the necessary maintenance...
- MV Empire MacCollMV Empire MacCollMV Empire MacColl was an oil tanker converted to a merchant aircraft carrier ship.MV Empire MacColl was built by Laird, Son & Co., Birkenhead under order from the Ministry of War Transport. She entered service as a MAC ship in November 1943, however only her air crew and the necessary maintenance...
- MV Empire MacKayMV Empire MacKayMV Empire MacKay was an oil tanker constructed with rudimentary aircraft handling facilities as a merchant aircraft carrier .MV Empire MacKay was built by Harland and Wolff, Govan under order from the Ministry of War Transport. She entered service as a MAC ship in October 1943, however only her air...
- MV Empire MacMahonMV Empire MacMahonMV Empire MacMahon was an oil tanker converted to a merchant aircraft carrier or MAC ship.MV Empire MacMahon was built by Swan Hunter, Wallsend under order from the Ministry of War Transport. She entered service as a MAC ship in December 1943, however only her air crew and the necessary maintenance...
Rapana class oil tankers
8,000 tons standard, 16,000 tons deep load, 12 knots, 3 aircraft, crew 118 (64 RN plus 54 MN), converted 1942-44. Anglo-Saxon Petroleum Company tankers. No hangar and lift; aircraft maintained and stored on deck. Armament: 1 x single 4 in (102 mm) QF MK IV, 2 x single 40 mm Bofors, 6 x single 20 mm Oerlikon cannons.- MV AcavusMV AcavusMV Acavus was one of nine Anglo Saxon Royal Dutch/Shell tankers converted to become a Merchant Aircraft Carrier . The group is collectively known as the Rapana Class....
- MV AdulaMV AdulaMV Adula was one of nine Royal Dutch/Shell oil tankers converted to become a Merchant Aircraft Carrier . The group is collectively known as the Rapana class....
- MV AlexiaMV AlexiaMV Alexia was one of nine Royal Dutch/Shell oil tankers converted to become a Merchant Aircraft Carrier . The group is collectively known as the Rapana class....
- MV AmastraMV AmastraMV Amastra was one of nine Anglo Saxon Royal Dutch/Shell oil tankers converted to become a Merchant Aircraft Carrier . The group is collectively known as the Rapana class....
- MV AncylusMV AncylusMV Ancylus was one of nine Anglo Saxon Royal Dutch/Shell oil tankers converted to become a Merchant Aircraft Carrier . The group is collectively known as the Rapana class....
: operated Swordfish II of ‘O’ Flight, 860 NAS - MV GadilaMV GadilaMV Gadila was one of nine Anglo Saxon Royal Dutch/Shell oil tankers converted to become a Merchant Aircraft Carrier . The group is collectively known as the Rapana class....
: operated under the Dutch ensign with Swordfish of 'S' Flight, 860 NAS - MV MacomaMV MacomaMV Macoma was one of nine Anglo Saxon Royal Dutch/Shell oil tankers converted to become a Merchant Aircraft Carrier . The group is collectively known as the Rapana Class....
: operated under the Dutch ensign with Swordfish of 'O' (later 'F') Flight, 860 NAS - MV Miralda
- MV RapanaMV RapanaMV Rapana was one of nine Anglo Saxon Royal Dutch/Shell oil tankers converted to become a Merchant Aircraft Carrier . The group is collectively known as the Rapana class....
: operated Swordfish II of ‘L’ Flight, 836 NAS
Amastra and Ancylus ceased operating Swordfish in late 1944, the empty decks often being used to ferry aircraft from the USA to the UK.