DaySailer.org Forum

Roger,
I am also going to be rebuilding and refitting my DSI this winter. Tomorrow in fact I start. During my inspection of the hull and deck I notice a number of hairline cracks around fittings and in the transom well. I have seen none in the hull bottom but have seen several around thru hull fittings, Bow eye, transom eyelets and drain. Any ideas on causes for these and/or a repair procedure. My concern is that these my be stress cracks. Any help would be appreciated.
-Dave

Hi Roger,

If they are truly hairline (you can barely, if at all, feel them) they are purely cosmetic gelcoat cracks. If you could barely fit a razor blade in them and/or they aren't deeper than 1/32" the same is true. If they are wide enough to fit a screwdriver in and/or 1/4" deep or more you have fractured the underlying fiberglass and have a structural problem. I doubt this is your problem. Cracks around fittings are more likely compression crack caused because the screws holding them on have compressed the gelcoat and fiberglass. I would only get concerned if the fittings are loose and getting then retightened is difficult (I just keep tightening them and the nuts on the underside just keep pulling up into the glass!) If you can see through the cracks to the other side you need major fiberglass repairs.

The only cracks that truly concern me is the fittings on the deck where the side stays and forestays attach. If in doubt have someone else who sails alot look at them.

To fix cosmetic cracks scratch to crack open and smear some new gelcoat (with hardener) into the crack with a squeegee. Let it cure. Sand lightly with 600 & then 100 grit wet/dry sandpaper. Hand buff with rubbing compound.

Sorry I didn't respond sooner. I think I was reading the 'joined' date rather than the posted date and treated it as an old thread.

Anyhow, KAbay has outlined it very well. Spider cracks are typically due to surface stress, and unless they go down to the cloth layer, should not cause you any structural concern. I used a dremmel tool to widen the cracks prior to applying gelcoat for cosmetic reasons.

If a crack does go down to the cloth layer, and you see delamination, but no tears in the cloth, then a more significant repair is needed. If the area is not large, ie less than a 1/2 inch beyond the crack, I would clean it with acetone, and let it dry for quite a while. Infuse the separated layers with resin and hardner and compress the layers with clamps, weights, etc. Repair the gelcoat as indicated earlier.

If the cloth is torn, then a major repair will be needed. Sand or grind down past the damage and feather up to two inches on either side. Build up new layers of cloth resin and hardner, feathering/sanding progressively further out with each layer from the bottom to the top. Finish with a gelcoat layer, sand and buff to match the surrounding surface. Check this site for details:

http://www.westsystem.com/ewmag/19/Replacing_Core.html

I'm not sure about this next statement, but it is my belief that you see stess cracks on deck more often than you see stress cracks on a hull, due to two factors. The first is the thickness of the deck being more, thereby increasing surface tension as it cannot flex as easily. The second is that there are likely less stresses on any one place on the hull, as pressures are more evenly distributed.

I have a particular spot on one of my cockpit seats that is all spider cracked. It matches perfectly with where the end of the boom would come down in an unsupported drop, like when the previous owner dropped the sail. I have a number of other such inpact injuries along the gunwale where the rubrail would typically touch the dock. In contrast, I have no stress cracks on the foredeck, nor on the cabin sole, other than where the mast or blocks are attached.

Thanks for the repair info. I'll let you know how it works out. I have also just flipped my boat in my garage. I took insulating foam that expands 3:1 and filled several large boxes with the stuff. This should keep my boat off the floor and high enough that I can work on top and underneath.
-Dave

Thanks for the info on the hair line cracks. I found a local shop that let me practice on his customers boats for a little while before I did my own. He watched to keep me on track. Worked great. Mine are almost all gone. Nothing major at all. Thanks for the 1/32" rule. Ready to paint. The old threads on the CB leak allowed me to repair mine while upside down, looks like a beached whale but won't know until it gets in the water.
-Dave