# Hairline cracks - how to repair



## mearsy (Mar 7, 2011)

Good afternoon,

I have a 2011 Rapido 700 and have just noticed (whilst cleaning the roof) a hairline crack on the moulding on the roof and a small star shaped crack hidden behind the front roof moulding.

Neither are very big....the crack is approx. 2" and the star crack 0.5".

Anyone have tips for a DIY fix?

Any experience with proprietary products for repairs?

Look forward to hearing from you.....


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## gaspode (May 9, 2005)

Is this the same problem I spotted here:
http://www.motorhomefacts.com/ftopicp-1232233.html#1232233

If so, just grind or scrape out the line of the crack and fill with a bead of Sikaflex (or similar PU sealant). Rapido Wokingham tried repairing mine by replacing the gelcoat but it just cracked again, a bead of Sikaflex sorted it eventually and the cracks haven't re-appeared or propogated.

It's due to the rigidity of the rear part of the roof meeting the flexible vertical part of the front moulding at a sharp corner - bad design. Rigid repairs won't work but if the repair is flexible (as with a PU sealant) it should be fine. As the skin is double at this point it shouldn't lead to any leaks as long as the crack doesn't spread too far before you rectify it.


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## Jimblob44 (Oct 26, 2013)

It might be an idea to drill a small hole at the ends of the cracks before filling, this stops them in their tracks literally. If it is just surface cracks they should be feathered out by sanding before filing.


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## VanFlair (Nov 21, 2009)

If it's fibreglass which I think it is, don't drill a hole in it as the crack is only in the gel coat not the substrate which is made with random glass mat so crack don't run anyway.

The advice from gaspode is good, you could grind the gel back and put more gel on but if it where you can't see it something flexible is better anyway.

Martin


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## mearsy (Mar 7, 2011)

Hi Guys,

Thanks for the replies.....

Gaspode it's not like that issue....it really is a fine hairline crack on the rear roof moulding.....

The star crack (about 0.5" dia) looks as if something has hit the roof (a stone perhaps)...it is lifting slightly.

When you say grind it out, would roughening up with sandpaper suffice?

ATB


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## VanFlair (Nov 21, 2009)

A hairline crack just in the Gelcoat is not really a problem, if you want to do something you could degrease it and just run a bit of white paint over it or a bit of sealant, really anything that keeps moisture out.

The star crack is possibly from something undeneath the panel applying pressure, it could be roughness on the underside of the panel or from something else like a screw head. Again just degrease or rough up slightly and the put on anything to seal it.

Are you sure these are actual crack rather than cracks or star crazing in the mould that have transferred.

Martin

Oops just read your reply again and you say lifting slightly so forget what I said about the mould.

If you have any fibreglass/polyester resin you could let this run into the cracks, if you warm it slightly it will make the crack suck in the resin and stop any of the gel from lifting any more.


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## mearsy (Mar 7, 2011)

Thanks again guys....anyone have experience of "Captain Trolley's Creeping Crack Cure".......sounds wonderful??!!!


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## gaspode (May 9, 2005)

> Gaspode it's not like that issue....it really is a fine hairline crack on the rear roof moulding.....


In that case are you sure the rear moulding is GRP? On mine the rear mouldings are ABS.

In any event, same advice applies - providing the damaged areas are out of sight - just use a bead of PU sealant to seal them. If the damage is so slight I would think that a quick rub with a rough abrasive would be fine as preparation.


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## mearsy (Mar 7, 2011)

This is the area......


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## mearsy (Mar 7, 2011)

This is better....its on the inside of this area


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## Zebedee (Oct 3, 2007)

> mearsy said:- Thanks again guys....anyone have experience of "Captain Trolley's Creeping Crack Cure".......sounds wonderful??!!!


I've got a bottle you can have for nothing. Only one squirt used.

Does that tell you enough?

I found it about as much use as a chocolate teapot! Worst of all it made using something else (like Sikaflex) very difficult, because I had to clean out the Captain Birdseye rubbish first.

Dave


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## gaspode (May 9, 2005)

> This is better....its on the inside of this area


In that case I'd be pretty confident that it'll be ABS, not GRP.


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## VanFlair (Nov 21, 2009)

gaspode said:


> > This is better....its on the inside of this area
> 
> 
> In that case I'd be pretty confident that it'll be ABS, not GRP.


I wouldn't expect star cracks in ABS but not sure so I'm out.


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## gaspode (May 9, 2005)

> I wouldn't expect star cracks in ABS but not sure so I'm out.


That's quite true, there wouldn't be any gelcoat cracks either as there is no gelcoat. :? 
Furthermore, from where the OP seems to indicate, that area may well be the anti-hail skin.
Same advice from me though whatever it is, bead of sikaflex.


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## erneboy (Feb 8, 2007)

Just to second what Dave said about Capt. Trolley or whatever it's called. I have some too, tried it a couple of times and found it useless, Alan.


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## mearsy (Mar 7, 2011)

Thanks to everyone......sikaflex it is then!!


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## Poulbot (Nov 8, 2013)

I was looking for some rope but just happened to notice this product.
Might be of some interest. I haven't tried it myself.
http://www.boatsnbits.co.uk/acatalog/Captain_Tolley_Products.html#aCTCCC70

EDIT: Sorry, just seen above posts also mention this product.


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## VanFlair (Nov 21, 2009)

Better stick with the rope.


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