I had a chunk of gelcoat and glass taken out by my dock and a maniac driving another boat speeding through a no wake zone and it cost me $700 for a professional glass rebuild and gelcoat spray. The work was guaranteed for life and this person is highly rated. My sugesstion to you is to stay away from that particular boat. That looks like the lower keel portion of the boat and who knows how long it has been like that. If the glass has absorbed water, which I am sure that it has, it most likely has already started de-laminating. If that is the case, what looks like a minor scrape could result in thousands of dollars for repairs, fiberglass removal, rebuilding, etc. I have had three Sea-Doo boats thus far.... just my two cents.