I have a 52 year old 38 foot sailboat. Over the years have had to do various repairs.
The best option is to cut out the rotted area, make a new piece to fit and then epoxy and screw it in place.
The next option is to use West System epoxy with their high density filler and fill in the area where the rotted wood was.
I tried Git Rot years ago. It did help but when I later took that area apart there was hard wood at the holes where the Git Rot was injected but still soft a few millimeters away.
If you have questions plse let me know
