This assumes that you have another group of fighters for CAP.
Now, now, before you get on my case about 'of course they have another potential CAP' or 'what sort of moron doesn't bring enough fighters to trade off' hear me out. Both
wikipedia and this
site claim Courageous's only air group at the time was the
811 and
822 torpedo bomber squadrons for a total of 24 Swordfish.
It seems plausible that they didn't want to reserve their biplanes for CAP, given that would remove their strike capability.
Now of course I'm staring at that above statement with incredulity. Why do you only bring 24 torpedo biplanes on a carrier which supposedly has room for 48 planes? Why are you still using biplanes?
They were on ASW patrol. There was literally nothing else they were supposed to use their planes
for, aside from intercepting potential enemy air attack (which Swordfish would be helpless against anyway).
And if your fleet carrier has nothing more than 24 planes on it, what the fuck are you even
doing? A fleet carrier's entire purpose is to carry a large number of planes (and have 28+ knot speed). If you're carrying fewer planes than a goddamn jeep carrier or light carrier, you're doing little more than risking a capital ship for minimal gain. Sending out a fleet carrier into hostile waters (or contested waters) without any fighters at all is just plain dumb.
Also, reserving anti-ship strike capability in exchange for having no CAP up when you're on goddamn ASW patrol is just plain dumb.
Now, even biplanes are still useful in ASW--the key is the ability to spot submarines via aircraft, which are in a better position to spot submarines than anyone else, and they can cover far more ground than ships can for searching. But again, sending half of your small screen away to help a single merchant ship--when you don't have any aircraft to keep track of the supposed submarine in the first place--is just leaving yourself wide open for minimal gain.
You mean the Swordfish? The Swordfish is a legitimately good airplane though. It can carry just about everything you might care to hang off it (the reason for it's nickname of "the stringbag"), and it could happily take off even when the carrier was at a dead stop.
It was slow as shit, but that didn't matter as much in the Atlantic where nobody else had carrier planes.
It
did matter, though, because Swordfish still had to contend with enemy aircraft and enemy AA. Swordfish were not exactly rugged, being outdated biplanes. Being slow as shit was bad for a torpedo bomber, since it made a vulnerable strike profile even more vulnerable to AA fire and enemy planes.
Being able to take off from a carrier at a dead stop isn't all that good of an advantage, considering that if your carrier is at a dead stop, it's quite possible that it's sustained critical damage that would render flight operations impossible anyway. It'd mean you wouldn't have to turn into the wind at all, sure, but seeing as the RN still managed to do so anyway and get a fleet carrier sunk in the process, it really didn't amount to anything.
I will give it credit, though: it did a spectacular job of making the Bismarck look really bad when it couldn't stop a squadron of slow biplanes from making a successful (non-hammer-and-anvil, even) torpedo run--in other words, flying low, straight, slow, and level. And they pulled off the Taranto Raid well enough.