Boat repair work advice
Discussion
There is a polished steel rail in the far right of the picture bolted to the hardwood that is on each side of the top deck above the main cabin. This is approximately 4'/ 5' long with 4 sets of bolts going through the rail, hardwood and GRP.
Bolts had come loose and bearing in mind I am looking to improve the woodwork under this rail figured I would take off the roof lining so could tighten the bolts up from the inside.
Removed the roof lining last night on one side and have immediately seen a problem. Where the bolts have come loose water has ingressed through the bolt holes and on 2 of the bolts softened the inside of the grp.
So racking my brains last night figured I should:
Remove all bolts and the polished rails.
Dry off any water, remove flaky crappy grp, and refill with marine filler.
sand/ varnish wood above.
put bolts back through, drill through the new marine filler where necessary for the bolts.
Now that part is all fine, but was hoping for advice on stopping water from ever getting in there again and also advice on how to stop the bolts from coming loose?
Do I put a squirt of sikaflex in the bolt hole to seal from the outside just prior to tightening the bolt to seal it?
Do I use one of those nylon nuts on the inside of the roof lining so it will never come loose? or perhaps try to use 2 standard nuts on each bolt? Perhaps I use normal nuts and once tight cover with marine filler so the nuts cannot turn?
help....?
ETA RIGHT!
Edited by m0ssy on Thursday 7th July 10:07
Simpo Two said:
If you think the mounting is vulnerable to further movement/loosening, do you have room to run a batten of wood underneath and then bolt through that as well?
Yes tis a possibility but not really the way I wanted to go forward.... although the batten would allow me to over-tighten without risk of cracking the grp 
so maybe the way forward....Take no notice of Simpo he doesn't understand the additional stresses and strains that a seagoing vessel goes through. Blutac indeed. 
http://www.whitstablemarine.co.uk/showpartnumber.a...
When you say the GRP has gone soggy what do you mean? Glassfibre doesn't generally do that unless it is breaking down from frost or capilliary damage.
Are you sure the deck isn't balsa cored or something as that is the normal type of failure where the core gets soaked. If it is you need to remove that and replace or it will travel further.
http://www.whitstablemarine.co.uk/showpartnumber.a...
When you say the GRP has gone soggy what do you mean? Glassfibre doesn't generally do that unless it is breaking down from frost or capilliary damage.
Are you sure the deck isn't balsa cored or something as that is the normal type of failure where the core gets soaked. If it is you need to remove that and replace or it will travel further.
MOTORVATOR said:
Take no notice of Simpo he doesn't understand the additional stresses and strains that a seagoing vessel goes through. Blutac indeed.
http://www.whitstablemarine.co.uk/showpartnumber.a...
When you say the GRP has gone soggy what do you mean? Glassfibre doesn't generally do that unless it is breaking down from frost or capilliary damage.
Are you sure the deck isn't balsa cored or something as that is the normal type of failure where the core gets soaked. If it is you need to remove that and replace or it will travel further.
To be fair chap its definately glass fibre, the bolts have come severly loose on the opposite end to the picture above and the water ingress has not been good to it. There is even a water stain on the inside of the roof panel now removed so its broken it down over a long period of time. I believe buy cutting it all away, drying with a hairdryer and getting marine filler in there should do the trick especially if I stop all future water ingress. http://www.whitstablemarine.co.uk/showpartnumber.a...
When you say the GRP has gone soggy what do you mean? Glassfibre doesn't generally do that unless it is breaking down from frost or capilliary damage.
Are you sure the deck isn't balsa cored or something as that is the normal type of failure where the core gets soaked. If it is you need to remove that and replace or it will travel further.
The product you have shown above looks the stuff, although need it in a hurry so will pop up the road to get this at luinchtime which alkso looks good http://www.clasohlson.co.uk/Product/Product.aspx?i...
So... looks like I can waterproof the outside, is my best method for the inside batten, large washers, and those nylon type locking nuts? or shall I just use normal nuts witha big washer and marine filler on top once tightened?
ETA : the slightly wet/ soggy bit I refer to is about 60mm diameter circular area immediately around the nuts/ washers where th fixings are in one bolt area.
Edited by m0ssy on Thursday 7th July 11:39
m0ssy said:
MOTORVATOR said:
Take no notice of Simpo he doesn't understand the additional stresses and strains that a seagoing vessel goes through. Blutac indeed.
http://www.whitstablemarine.co.uk/showpartnumber.a...
When you say the GRP has gone soggy what do you mean? Glassfibre doesn't generally do that unless it is breaking down from frost or capilliary damage.
Are you sure the deck isn't balsa cored or something as that is the normal type of failure where the core gets soaked. If it is you need to remove that and replace or it will travel further.
To be fair chap its definately glass fibre, the bolts have come severly loose on the opposite end to the picture above and the water ingress has not been good to it. There is even a water stain on the inside of the roof panel now removed so its broken it down over a long period of time. I believe buy cutting it all away, drying with a hairdryer and getting marine filler in there should do the trick especially if I stop all future water ingress. http://www.whitstablemarine.co.uk/showpartnumber.a...
When you say the GRP has gone soggy what do you mean? Glassfibre doesn't generally do that unless it is breaking down from frost or capilliary damage.
Are you sure the deck isn't balsa cored or something as that is the normal type of failure where the core gets soaked. If it is you need to remove that and replace or it will travel further.
The product you have shown above looks the stuff, although need it in a hurry so will pop up the road to get this at luinchtime which alkso looks good http://www.clasohlson.co.uk/Product/Product.aspx?i...
So... looks like I can waterproof the outside, is my best method for the inside batten, large washers, and those nylon type locking nuts? or shall I just use normal nuts witha big washer and marine filler on top once tightened?
I'm willing to bet you a pint of beer though that the deck is balsa cored as that is the norm rather an oddity.
Mould - release agent - Gelcoat - Glassfibre - Balsa core - Glassfibre.
Have you actually taken the Bolts out yet to see how thick the deck is? I reckon the bolts are loose because the core has crushed rather than them just unwinding themselves and the softening you talk about is the fact that the inner glassfibre isn't particularly thick. The strength comes from the composite.
For aplications where there is a mix of GRP and wood I'd suggest either butyl rubber mastic or polysulphide.
At each point where the bolt passes through the metal/wood or GRP a little counter sink round the hole helps, you end up with a little donut of selant around the bolt.
Nylocs underneath would be good.
At each point where the bolt passes through the metal/wood or GRP a little counter sink round the hole helps, you end up with a little donut of selant around the bolt.
Nylocs underneath would be good.
Simpo Two said:
Interesting, we're advised NOT to use silicone sealant! Mastic tape stays flexible for longer they say, ideal for all that salty wave crashing I'd have thought... Sikaflex used on smaller fittings though.
You are right as well Jon. For two reasons - Standard silicones can't deal with salt water and below the waterline it is preferable to use a mastic or polysulphide type product that provide an adhesive property as well.Silicone has next to no adhesive properties so is good enough for most purposes as it is just a gasket so to speak. Underwater you want the added security of a bolt shearing not meaning the fitting disappears.
m0ssy said:
Cheers chaps, taking a combination of everyones advice (except simpos blue tac idea 
)
Doh, think of it as MARINE blu-tack )
Suspect it's what they used before the modern stuff was invented. That said, Motorvator is the man for this as he does salty wave crashing and I don't.
Simpo Two said:
m0ssy said:
Cheers chaps, taking a combination of everyones advice (except simpos blue tac idea )
Doh, think of it as MARINE blu-tack )Suspect it's what they used before the modern stuff was invented. That said, Motorvator is the man for this as he does salty wave crashing and I don't.
If I find myself in the North Sea something has gone seriously wrong. A big tsunami could wash me into the Grand Union I suppose, and you would end up on the Broads... and then there'd be like another big tsunami, and I'd be washed into the Oxford Canal and you'd like be washed into the Fens? And then we'd be washed all the way to America and stuff? How awesome is that!
He wrote a book you know, Awesome Wells.
He wrote a book you know, Awesome Wells.
Huntsman said:
I like Arbomast BR and its dead cheap.
On GRP I find polyurethane very good but its no good for wood, if you try and dismantled you'll break the wood before the polyurethane lets go.
On GRP I find polyurethane very good but its no good for wood, if you try and dismantled you'll break the wood before the polyurethane lets go.
did I hear my favourite word 'cheap' 
(for reference my favourite 2 words that i don't hear often enough together is 'free bar')http://www.marinemegastore.com/product.asp?pf_id=E...
Looks good stuff Huntsman, dirt cheap compared to sikaflex 291i
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