Totally repairable. Surely its not cosmetic but you can fix much worse in fiberglass. Can you get a replacement rudder? The hull repair is one thing but fabricating a new rudder and tiller is another.
I can hardly see the wood inside but if it’s dry, hard and not damaged by the rip out then why not. Shouldn’t be hard to bond a new panel to the wood and then laminate it to the rest of the structure.
Was the rudder hinge bolted to this wood? Because if it was then i’m not sure how it could’ve ripped out so cleanly.
It’s hard to tell, but I’ll do some poking around today.
The original hardware was drilled into the wood over the panel and sealed. The rudder had a pin that went through the mount and it’s own hardware. That pin likely bounced out and torqued the whole piece off.