Aircraft
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.
However, there is evidence that Sea Hurricanes were deployed aboard MAC ships. According to the Fleet Air Arm historical website:
"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.
Read more about this topic: Merchant Aircraft Carrier