spider cracks

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johnsw

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Anyone have any experiences with gelcoat spider cracks? I was doing some cleaning this weekend, and the rust stains that settled at 2 of the bowrail supports (middle 2 on starboard side) on my '04 2120SC made some cracking noticable. Both have 4 cracks radiating about 90 degrees apart, going about 3/4" out. My prior 2 boats never had them, so I'm not sure what (if anything) I need to be concerned about at this point. Seems like more of a cosmetic issue, but do they eventually stabilize or just keep going?

Also, what's the best way to get those stubborn rust stains out of the fiberglass that settle around those baseplates? I've tried things like Flitz and a toothbruch, but it's a slow go at best.

John S.
 
For the rust stains, try Soft Scrub w/ Bleach or Collonite fiberglass cleaner.

-- Tom
 
johnsw":3c9z11ml said:
Anyone have any experiences with gelcoat spider cracks? I was doing some cleaning this weekend, and the rust stains that settled at 2 of the bowrail supports (middle 2 on starboard side) on my '04 2120SC made some cracking noticable. Both have 4 cracks radiating about 90 degrees apart, going about 3/4" out. My prior 2 boats never had them, so I'm not sure what (if anything) I need to be concerned about at this point. Seems like more of a cosmetic issue, but do they eventually stabilize or just keep going?

Also, what's the best way to get those stubborn rust stains out of the fiberglass that settle around those baseplates? I've tried things like Flitz and a toothbruch, but it's a slow go at best.

John S.

I use FSR for rust stains and it does all the work... apply... let sit for 30 minutes (much less on lighter stains)... hose off!
 
Not sure what is causing the stains, but I'll use liquid bleach in a spray bottle, or soft scrub with bleach for most 'normal' stains on my boat.

If the stain is tougher, FSR or Marykates On/Off will do the trick. Just be careful not to get any on your skin and hose the area off well after cleaning.

Once she is clean, I swab her down with Woody Wax so she stays that way. :wink:
 
Thanks for the recommendations. This early in the season though, it's a tough call - clean the boat or go fish.

JS
 
johnsw":3fa348i7 said:
Anyone have any experiences with gelcoat spider cracks? Seems like more of a cosmetic issue, but do they eventually stabilize or just keep going?
All I can offer is some info I got last weekend with a member of my boat club who has a fiberglass boat restoration business. He does everything from Awl Grip paint jobs to complete stringer and transom rebuilds.

Firstly, remember that the tensile strength of gelcoat is very hard, therefore it is very brittle. Stress cracks are cosmetic and occur when the substrate layer moves and the harder gelcoat can't "flex" with it, so it cracks.

Second, my friend reports that the gelcoat made nowadays is not on par with that made many years ago. This is not Parker's fault, but that of the gelcoat industry and environmental standards. Regarding non-white or beige gelcoat colors, he further advises anyone who really wants a colored hull to go with Awl Grip paint job and not with colored gelcoat ... he showed me a green hull not 4 years old that was already severely chalked. Nor is gelcoat applied as thick as it was on older boats, though here too, I would surmise that Parker is among the best.

One other reason for stress cracks appearing on new boats is that many companies pull their boats from the mold far too soon and apply deck hardware that gets torqued tight. The glass on the outside may be hard, but inside its still curing, or "green" as they say in the trade. Now I would bet that Parker leaves their boats in tbe mold longer than just about anybody else, but in the end, boats don't sit in the molds curing today like they did 10 years ago.

With all that said, I'd bet the predominant reason you see it where you do is that's just about the entry area where the hull is slamming into the waves ... the hull moves up a bit, as does the deck, but the deck is constrained from "above" by the rail mounting pads. It is the pad that is being forced "down" into the deck and thereby causing the stress cracks ... by my best guess anyway.

You could loosen the rail all the way around and add a suitable 1/16" to 1/8" thick heavy durometer washer between the deck and rail ... if you really wanted to go to that trouble. I'd remove one rail bolt at a time, having done a Parker rail before ;) .

Normally, stress cracks will stop once they reach the pont of flexation. Yes, you can grind them out with a dremel "V" bit and then fill them ... but if the cause is still there, then yes too, they will reappear.

Hope this helps ...
 
Thanks for the great info, Dale. At this point, sounds like it's just an appearance thing so I can live with small cracking. Like I mentioned before, they're not that big (yet) and this is the first time I've noticed them. I'm only in the water 3 weeks now and nothing really nasty when running, so I'd believe that the cracks were there last year but I just didn't see them. If they keep creeping, then I'll need to investigate closer to figure out what might be going on to try and soften the stress points and stop whatever's happening before I invest in having the gelcoat repaired.

Thanks again

JS
 
For rust stains or tannic acid, go to the local industrial chemical supply house, and buy a 55# bag of oxalic acid (crystals). Take a cup of crystals
with water and microwave for 2 min., and stir. Then, pour (a funnel helps)
into a gallon jug, add water, and shake.
Use an atomizer bottle or garden weed sprayer, and stand back...it will all disappear.
You're making at about 59 cents a gallon what they are charging you $18 for at the marine stores.
Be sure to flush with clear water.
Also, rusty bolt? Let it soak overnight in the solution...brand new.
 
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