Before I answer your question, I have to ask, why the heck would you want to add a skeg?
It is a huge and difficult job to do right. I designed a modification to a ketch
that had serious steering
problems in which moved the rudder
and added a skeg. It is not easy to get adequate support for the skeg on a boat that was not originallyconstructed with a skeg. On the boat that I worked on we made a glass off of the boat. In order to get proper strength we molded the skeg with an extension leg that extended through the bottom of the boat to the underside of the deck
and then added a bulkhead on either side that was glassed in on all sides to the deck
, topsides and hull
bottom. We also added a knee that went roughly 20 inched forward of skeg leg. We then glassed the skeg to the hull
with a large diameter fillet that gave us a lot of contact area. we were dealing with a hull that was roughly an inch thick which allowed use to taper the connection deep into the hull laminate.
In our case we were adding an outboard
rudder so we did not have a problem with an inboard rudder tube or designing gugdeons and pindles to work with the rudder post.
In other words, you had better have a really good reason to want to add a skeg on a Catalina
because otherwise you would be way far ahead just buying
a boat that already has a skeg hung rudder.