That is one hell of a "hole", sorry to hear about that ma8. This is not a gelcoat crack that lends itself to the "grooving out" technique. It is - IMHO - major damage to the hull. The fix will be much more involving than what you have described.
I would first check with my insurance company, if you have good policy and low deductable, it might be good time to use them.
But BEFORE you do this, be aware that some insurance companies are obligated to report the incident even if you elect not to file a claim. They will put the incident in your records to begin with. Check with your agency before you talk to them about an actual incident.
Also, get an estimate from at least two good and reputable marine service facilities. Some insurance policies will pay you the choice of
- Pay you x% (about 75-80%) of the estimate and you handle the rest (this also means that you can do it yourself using your insurance money)
- They will handle all payments to it can only be paid to the marine service facility not you.
If you decide to do it yourself, let us know, we can talk you though it but the results will be as good as you execute the steps, of course.
BTW, you can't use gelcoat on top of epoxy. If you are going to gel at the end, you have to use poly resin