was cleaning the boat and found this, looks like just gelcoat. glass under looks good, I was going to grind out cracks to v them and use gelcoat paste to fix? your thought? Do's.....Dont's?

Almost looks partially delaminated. I would get a few expert opinions

Too big not to have an expert look at it imo...

Like said - it looks like delamination. Get an expert to look at it. It doesn't look like surface damage to me.

That is not just gel coat damage and does not look like its from an impact.

Looks more like stress cracking from structure issues

I put a grinder to the crack to clean out and to get a better look, fiberglass is solid under the removed gel coat, gel coat seams to be still bonded to fiber glass at edges, also I blew this picture up so you guys can see it better so I think picture looks allot worse then it is, total length of crack is about 12"..ill take another picture of it cleaned up. also I don't know how long this crack was exposed to water setting at the dock, should I be concerned about water getting in there?

If the glass is solid under there, you didn't get into the core (if there's one) and its not weeping moisture after you ground it down, then i wouldn't worry about it being exposed to water.

still a weird looking crack though...is there an impact area? the gel should be spidered outward from the center of the impact area.....looks to me like something hit from the inside out....you have an anchor bouncing around the nose during a hard run??

That is not good at all. It all most looks like a previous repair going bad. Do you have any history on the boat? Otherwise it looks like something is flexing and causing the the failure. Then add water pressure (can not compress liquid) trying to blow it apart. Can you see anything on the inside near the problem area? Look for loose stringer or bulked. Do get it checked out.

I've seen lots of fiberglass damage (lots lol) thats not a random surface defect. Looks to me more like an old repair showing itself, or an interlaminate overlap that let go for some reason. Tough to tell without seeing it first hand post more pics when ya can. That something your really going to have to determine the cause of so you can repair completely.