Looks like someone tried to repair it before without permanent success.
Proper repair would necessitate removal of all the current material. Looks like the sea creatures hav developed a home in the fiberglass.
Then properly rebuild the fiberglass.
Drill a proper hole for the cutlass bearing - fit and angle are critical.
Then finish the area fair.
It will be time in the yard, skilled labor, and material expenses.
A SWAG would be $10,000. But who knows. could be a lot more dependent on what is found as you clean the area up.
Your going to have some shaft/engine alignment issues to address as the project matures.