Merchant Aircraft Carrier (MAC) Class CV-(M)

In 1941 convoys desperately needed aircraft cover to defend against German U-boats. However both warships and merchant ships were in such short supply, that taking hulls for conversion to aircraft carriers was out of the question. 

So, in classic British fashion an adaptation was proposed.   

The basic 1941 Admiralty minima for flying operations at sea was 390ft(118.9m) of flat deck and 11kts speed through the water. This could be met by the 8,000 ton (8,129 tonne) emergency war construction standard cargo hulls. So two grain carriers were ordered with flight decks and off-centre superstructure. The Merchant Aircraft Carrier (MAC) was born. 

MAC-ships flew the Red Ensign, were commanded by merchant marine officers, but had a small Fleet Air Arm contingent aboard. (In fact some swordfish aircraft carried the legend 'Merchant navy' instead of 'Royal Navy' on their fuselages. 

After the first grain ships were adapted, Anglo-Saxon Petroleum volunteered their larger 12,ooo ton (12,193 tonne) tankers for conversion. After some Admiralty misgivings, conversions began in 1942, and MV Rapana was converted by Feb-1943 with a flight deck of 460ft (140.2m). Flying operations from MAC ships were a great help in protecting convoys especially when two or more MAC ships were in a convoy.

On board each ship were the normal carrier equipment of arrester wires, fuel supplies of Avgas, fire fighting equipment and a  Deck Landing Control Officer. 

They were a great improvement on the first attempt to give convoys aircraft cover in the mid-Atlantic. With Catapult Armed Merchant ships (CAM-Ships) who launched their fighter from the ship but had no means of landing the aircraft. After their mission, if the aircraft was not within flying range of a land airfield, the pilots only option was to bail out and hope they would be picked up by a passing ship.

Later two Dutch MAC-ships joined the MAC Fleet. (Gadila and Macoma).  The were tankers which flew the Dutch naval ensign and whose mini air groups were provided by 860 Squadron, also a Dutch unit.

Although MAC-ship aircraft did not sink any U-boats they carried out many attacks which made the submarines submerge and break off their attack. Each convoy ship saved was of great importance during the dark days of 1943-44.

In their turn, the MAC-ships importance became less vital as escort carriers (CVE) began to join the Fleet in strength. So all MAC-ships were returned to purely merchant service, and a short era in the annals of aircraft carriers ended.


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This page last edited - 25 January, 2013.

Copyright Ian M King, except where otherwise indicated.