Reinstating Coach Roof Penetration After Removing Flue

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Hi Folks,

I am looking for some advice on reinstating the GRP on the coach roof after removing an old diesel heater flue penetration.

The hole is 120 mm in diameter and consists of (from the top) 1mm Gell Coat, 8 mm GRP, 20 mm balsa, 5 mm GRP, 3 mm ply headlining with vinyl backing.

To do this properly I need to cut back a chamfer into the top layer of GRP to a new diameter around 200 mm, insert a new balsa core and repeat the same sort of chamfer for the inner moulding. This would easily take the repair over the coach roof edge and onto the side bit.

I don't think that this is necessary and represents excessive work for not much additional benefit. The hole has been there for many years and as such has seen all the stress its ever likely to see i.e. the yacht is not going to split into two from this hole.

What I am thinking is that I will bond in a new balsa core around the same diameter and just build up the top and bottom GRP layers with discs of glass mat. The coach roof will require two finishes to match the grip pattern and the smooth Gell Coat. The inside doesn't have to be aesthetically pleasing as a new headlining will be used. I would of course clean up the hole before bonding, all is dry but dirty.

I have been quoted nearly £1800 to do the job professionally and correctly, by skilled shift wrights, who say they can more or less make the reinstatement invisible. I wouldn't be able to do this but £1800 is a lot of cash for a small hole.

What do you think and many thanks in advance.

BlowingOldBoots

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1800 is a ludicrous amount. The hole isn't very structural so I would suggest simply masking off underneath with some stiff plastic sheet and rebuilding/re-laying in situ, cut the balsa core back half an inch and replace with foam.
 
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Agreed, that's far too much! Have you considered leaving the hole and fitting a ventilator in it? Lateral thinking saves money...

Rob.
 
Cosmetics are the only issue I can see. Can you get a good gel coat match?
I assume the non-slip bit will need a coat over the whole area in the fullness of time anyway.
 
Fantasie 19 said:
That was my idea too... late as usual..... :rolleyes:
Click to expand...

Just done exactly the same thing. I fitted a fixed vent (can never have too much ventilation on a boat) that was big enough to cover all of the damage which in my case was a 9"dia area around a 4" dia hole. In your case a small opening hatch might be the answer.
 
My inclination would be to make up a nice hardwood plug for the outside, say about 16 mm thick with an 8mm rebate to the size of the hole and enough overlap for robust strength, chamfer the upstanding edges, round or square, your choice, nice coat or six of varnish, instead of hiding it unsucessfully you simply turn it into an intriguing feature. reinstate the core and GRP the inside and Robert's your male relative. There's no structural problem so far as I can see. We have just such a hole in our coachroof for the Newport Stove and our surveyor expressed no worry about that.

Incidentally do you still have the diesel heater and is it serviceable or restoreable? I ask because I know someone who is looking for one.
 
Thanks for all the ideas, it's appreciated. The space below is the heads / shower and it already has a vent but another would not go amiss. I doubt I could find a matching cowle.

I will go ahead and repair in GRP without chamfering after prepping the surfaces to be bonded. I like the idea of capping off with a hardwood plug instead of a poor gel coat finish.

Ken - the heater is fully functional but now resides in my workshop.
 
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