As you note, fiberglass can be repaired. The term delamination typically describes an undesirable reversal of the manufacturing process. If that's what happened vs. striking an object then your insurance company isn't hanging you out to dry. If the fender rusts through the paint on your truck, do you expect your auto insurance company to fix that? If your water heater stops working, do you expect home insurance to replace it? As for "venturing in the that direction" on repair and you statement that you still owe a lot of money on the boat, you're stuck owing the balance due to the finance company regardless of what you do. Repair or not, you owe a balance they will seek to recover. If you let it repo, be prepared for the big hit on your credit rating and a likely judgement equal to the difference between the salvage value and the owed balance.

Welcome to the responsibilities of owning material things. What's the Nitro hull warranty say?