Rebuilt our non-opening ports
We rebuilt the two windows that were leaking the most on our '77 h27. They are not opening ports, but clear acrylic panes in white plastic frames.
1. Carefully pulled out the somewhat brittle frames.
2. Filled/rebuilt the wood core of the cabin side around the windows. (Some members have reported that the core was completely rotted way. They epoxied tubing around the window, then filled to the edge of the fiberglass with epoxy filler.)
3. Lined the opening and frame with Life Caulk in the right places.
4. Re-installed the old windows and frames, tightening the screws in the frame lightly to let the caulk set up.
5. Cleaned up any oozing caulk.
6. Came back and tightened the screws to firm.
The plastic panes of our windows were OK. You could have new panes made using the old as a pattern.
We are happy with the job which has not leaked in 3 years.
If your Catalina already has opening ports, then check the archives.