Stress cracks, need to worry?

[skijones]

I was waxing the bottom of the boat today (99 SNOB)and noticed some small, 1 to 1.5 inch long stress cracks in the gell at the leading edge of where the strut mounts and at the rudder box. On the inside, nothing around the rudder, but did find about a dime size area of the gell loose at the strut mounting. None of the fiberglas fibers seems to be cracked.

Checked the shaft alignment and it is perfect.

Is this something I need to worry about or just fix the gell? I have obviously hit something in the last year, but never had a vibration, nothing on the prop, nothing on the rudder.

Great sight, enjoy the advise.

[Aarons01]

RE: Stress cracks, need to worry?

trade it in NOW (its an excuse for a new boat right?)

[SNobsessed]

RE: Stress cracks, need to worry?

SJ - I had similar cracks (PO had bent strut). When I was replacing strut, I had used paint thinner to clean up the sealant inside the hull. Luckily the paint thinner acted like dye penetrant & highlighted very fine cracks that I could not see before. So it is possible you also have tiny cracks inside.

I added several layers of cloth/epoxy inside, each one a couple inches bigger, to strengthen the area. You can get the materials for less than $50. On the outside, I dremeled the cracks & filled with epoxy. Haven't yet gelled them but probably should.

Good luck, just sharing my experience.

[DavidF]

RE: Stress cracks, need to worry?

Personally, I would not worry about it. Stress cracks do not necessarily mean trouble. Gel is hard and brittle, fiberglass composite is not. So, the strut/rudder probably felt some excess stress at some point that cracked the gelcoat and that is the extend of the damage. It is NOT unusual for stress cracks on older boats. My boat has stress cracks around the platform brackets probably due to overloading. Am I worried...NO.

[skijones]

RE: Stress cracks, need to worry?

Thanks, I did not think it was a big problem, but I hate to see cracks in my baby. Will dremel out the cracks and fix the gell. Will try the paint thinner to see if there are any further damage. If the 'glass was cracked, I would reinforce it, but don't think it needs it.

I still don't know how this could happen without any damage to the prop or rudder. I know it happened last year.

Again, thanks for the help. Great to be able to contact like minded people.

[adames]

What about the stress crackes around the rub rail? Can I fix them with gel coat?
They dont seen to be problem just want them fixed.

[DavidF]

Fixing with gelcoat is the only (right) way to fix the stress cracks. The technique is straightforward: grind out the crack to bare fiberglass and fill with gelcoat then sand smooth and polish. I use a dremal to grind out the crack. Now with all that said, more than likely you will be able to see the repair unless the boat is still fairly new. It is very hard to get a perfect color match given fading, minor formula differences, etc. Also, if you do not fix the root cause of the stress cracking, the cracks will return.

For the rub rail, the cracks were probably caused by stress by bumping into something hard with the rail. the other cause is from the screws holding the rail onto the hull. Normally, CC countersinks screw holes to reduce the stresses caused by the screw in the hole. However, when installing the rub rail, this practice is not possible or at least practical and they do not chamfer the holes...thus cracking. So, to fix those cracks you need to remove the rubrail, chamfer all the holes (of course fix the cracks) then reinstall the rubrail using the original holes.

You could probably do a search on the proper technique of fixing stress cracks so I will not go into that here....unless needed ultimately.