Duetto 2010 roof

Has anyone heard of, or experienced using , something that can be painted on a roof to cover hairline cracks?  I had a small leak problem which I thought was due to the roof light in the washroom.  However on close inspection my brilliant garage man has discovered cracks in the roof.   He has been doing some research and found something that can be painted on and it is guaranteed for 10 years!  
I just wondered if anyone had come across anything like this?

Thanks,
Sue

Fine cracks in gelcoat have been an issue for boat owners for many, many years, and I think if you ask any boat owner about products that you just paint over the top, they will laugh!

But of course we don't know what the product is, so who knows?

But I doubt it will be anything other than a short-term cover-up.

If it's in a section that is not visible, I would simply seal with a decent layer of sikaflex.

It's incredibly resilient stuff, flexible and will get into the crack and bung it up nicely.  A decent 'smear' a good distance around the entire damage would seal it all up no problem.

If the area is large though and covered with cracks, you probably need something more liquid that will cover a wider area easier and not be so messy.

I thought a 2010 Duetto would have been built on the high top (metal) roof Transit and not have a grp roof.

Many thanks for the replies.  I also had assumed it was a metal high top.  I had a phone call about the hairline cracks this morning and as the camper is at the garage I cannot check.  I am assuming because he said hairline cracks it would be fibreglass?  I assume you would not get hairline cracks in metal?
Just realised Roopert mentioned gel oat.  Is that a coating on top of metal?
As you can tell I am an ignoramus.   
Sue

As a compulsive boat buyer and doer uper I would deal with any gelcoat cracks by racking them out a bit deeper and using a colour matched gelcoat filler, sanding and polishing back to get a good finish.
But as others have suggested, your roof should be painted metal, no different to a car roof, I can't understand how you can have any cracks that would leak, at worst it may be paint damage, scratches or peeling, but this wouldn't leak.
I would ask for more info or have a look yourself, check the roof with  something magnetic, a fridge magnet for example, if it sticks then it is definitely steel.

Many thanks Enn.  Will do.

Sue

I didn't realise the last of the Duettos had a factory steel roof. If you have stress cracks in that, there's a serious problem somewhere!

The 2009 Duetto has a metal high top with a 1in. thick flat plastic/fiberglass false roof fitted to the top to enable the vents etc to be easily sealed to a flat surface rather than the corrugated surface on the steel hightop.
BUT the seal between the false roof and the steel top was a known problem acknowledged by the A/S service centre. The sealing mastic, and perhaps the original technicians technique, could result in leaks developing at the join.
The only way to be sure of a cure is to have the old seal fully removed and new mastic injected. not a task for the uninitiated. IF one gets it redone ask for a substantial mastic application, because if it is done prettily the seal is very thin and will not last!  The main fault I think with the 'as built' seal is that it was delicately done and insubstantial.  Really the best cure would be to remove the entire false roof, complete with vents and clean surfaces up ,then re-bed with a substantial bead of marine sealant. This would be very costly. A mastic seal over the top of the leaking one may work if thick enough BUT one needs to ensure that the  seal area and under surface is DRY.
Not a job to be done in the outside & damp but preferably inside after a thorough drying out.
frederic

Thanks Frederic.  I shall talk to my friendly garage man.  
Sue