I don't believe that the fiberglass
has much to do with integrity of the rig. Certainly not if the mast is keel
stepped. As Tropic Cat mentions this is a cosmetic repair. As to the cracks going deep, it really doesn't matter. The repair process of grinding out the crack and refilling with structural grade fiberglass is the same. In the video I learned from, the author states that in some cases he's had to go all the way through the original glass but that the new repair will be as good as the original should have been.
The one nice thing about a repair like this is that no exotic tools are necessary. An electric
drill with a carbide grinding tip will take care of the grinding out. A small airbrush with a small can of propellant does an excellent job of applying gelcoat to a small repair like this. They are available for around $25 U.S.
On the other hand, if this is the only repair that needs to be done. I'd just hire a guy that's got all the stuff and let him/her do it. Even allowing for the cure times, it's a one day job with most of that time spent waiting. A few minutes to grind out, about 15 min for the structural glass to cure, a bit sanding
, apply the fairing compound and wait another 15 - 20 min. The trickiest is to match the gelcoat color. In my case it took about 20 min., it might take much longer but usually not. The gelcoat should probably cure for about 4 hours before the final finish sanding
Like I said, for just a single
repair, which is totally cosmetic, it's probably easier to hire it done. I had a bunch so I learned how to do it myself.