Can you elaborate on wrapping the split tube? I would be concerned about getting the tube back to orig strength. In the event splitting the tube becomes my only option I would like to know more.
Simply cutting pieces of glass fabric long enough to wrap around the tube, wetting them with epoxy and then wrapping the tube with it, piece by piece with the seams staggered.
Since your tube is metal and after reading Denise's post, I'm beginning to think cutting the whole mess out and replacing with a pre-made fiberglass tube might be the easiest way to go. That's if you simply cannot get it out without cutting something seriously.
I once made a stern tube by very thoroughly waxing the shaft and then wrapping pre-wetted glass cloth round & round until I got the thickness I wanted. Sliding it off the shaft took a bit of effort but it came off. I then put some valve lapping compound in it, slid it back on and rotated it until I had a very nice precise fit - just enough to prevent "hydro lock" or whatever the proper term is for the lockup you can get when water enters a too perfectly tight mating surface.
If you cut out your entire rudder setup and cut it apart on a bench, as suggested earlier, you could create your own, perfectly mated rudder tube the same way and then simply glass/epoxy it in place with some added gussets for strength.
That would be a fairly big job, and certainly nasty in such a confined space though, so I'd continue as is for now.