We've discussed on here a few times about Nazi Germany building carriers, and the usual consensus is that it would be a total waste of resources and would actually impede their war effort. WI Hitler decided on a bit different option? Suppose he actually gets an inkling that invading England will require more than barges and that the RN must be dealt with some how? So, let's imagine that he takes a look around at the different planes around the world that are designed to sink ships (torpedo bombers, etc.), and has his people design some land-based planes that are specifically anti-ship in purpose. Since Hitler tended to be pretty fickle when it came to building things, I imagine he'd only allow a few squadrons to be built, basically enough to deal with the RN in and around the Channel.
So, how much affect will this have on the war? I'm guessing it will still be a waste of resources that ends up impeding the war effort, but not so much as a carrier fleet would have (I'm also guessing that he still won't launch Operation Sea-Mammal-that-must-not-be-named). Plus, the RN around the isles would likely suffer some more losses. Or, perhaps, the planes go to Italy?