Rudder Repair help advice - opinion

[drakes]

About a month ago I damaged the rudder on my Glander Cay. Still not exactly sure how it is possible. I have checked the shaft and the prop and all seem tight. However I did experience wrapping a line around the prop and I'm thinking maybe something nicked the inside of the rudder. It looks to me like there is exposed wood where something took a chunk out of the inside. Which I just discovered today.

It looks like wood cored - fiberglass covered rudder

I am going to have a diver help me pull the rudder Monday. I think if wood isnt completely rotted or soaked i can smooth out and glass over. My concern is that there isnt much clearance for example prop shaft has no zinc. Had the boat about 7 months but cant figure a way to fit one. So i am thinking of enlarging the cut out of the rudder so that i can maybe put a end come type zinc on and hopefully prevent something like this from happening again

Anyone know how to calculate the effect on steering or pull on helm etc? I dont need to do the whole thing but if i felt confident it wouldnt have too much negative effect i might take an inch off the whole inside.

Pictures attached. On the hard from March 2021 bottom job

Any one do something like this before? Thanks