It sure looks like multiple glass failures that not only compromise strength but would likely let in water. Hard to tell from the pictures if there is any additional damage to the plywood substrate, or whether the glass on the board itself is damaged (instead of just the glass reinforcing the fillet where the fin and board mate). 

While I suppose it's possible to remove the fin without destroying it, I'd bite the bullet and make a new one. Heat sufficient to soften that fillet might well damage the board. 

A cheap pull saw will let you trim it away pretty close to the board, and then (don't tell the hand tool police) a block plane (maybe not your $$$ heirloom model) will help with careful removal of the rest without the hazardous dust of a sander or grinder. Even if you have excellent power tool dust removal, hand tools are nice for more deliberate, careful work.

Hopefully you saved some scrap glass for the patch(es).

Good luck,

Patrick

���Yes. The plywood is also damaged around the fin. About 70% around the fin itself. I started to grind off the fillets around the fin but kept it on to help with pulling up the wood which I am currently doing surgery with a surgical knife to cut the splitters off that is keeping me from pulling it up flush. As Terry from clc advised to clean it, repair the fillets and FG. As long as it's sealed to be waterproof I'm good. It'll be under the water most of the time anyways.