I have tried one and it works fine, but haven’t installed yet. My 07 model 22 has the raised cockpit insert, and at the stern where the bilge pump sets is a solid area with no air pockets. When an in-hull transducer is placed in that spot and tested with a couple inches of water it works fine. I had planned on installing it permanently with the intentions of using as a backup when the stern mounted transducer eventually gets torn off; it is currently being held together with epoxy putty. Most likely what will happen is the stern transducer will get ripped off and I’ll be wishing I’d installed the in-hull.
I think C-dorys manufactured prior to the raised cockpit insert have an area at the stern that is un-cored fiberglass, so if you place your transducer there if should work fine.
