EagleSpeak has a post up about British and Dutch merchant ships used as aircraft carriers during WW2. Not “converted to aircraft carriers” like US escort carriers…”used as aircraft carriers”.
The ships had decks added for flight ops. No arresting gear. No hangers. No armored magazines or fuel compartments. Just a deck and a few extra guys to handle the aircraft.
The merchant ships continued to carry their standard cargo after the modifications.
There were two versions, the standard Merchant Aircraft Carrier (MAC) which carried four Fairey Swordfish torpedo planes and the Catapult Aircraft Merchantman (CAM) which carried one Sea Hurricane fighter.
As the name suggests, there was a (rocket-propelled) catapult to launch the plane on the CAM. Eight CAM ship launchings resulted in six German recon planes shot down. But remember the part about “no arresting gear”? The plane could not be recovered and had to be ditched after the flight.
Seems to Murdoc that the Swordfish, biplanes capable of (required to) fly low and slow, would have been ideal anti-sub platforms. And they apparently were. No convoy with a MAC ship along lost a ship to U-boats.
Go check out EagleSpeak for more info and some pics.