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filing a through hull

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welkman001 says:

Hi,

Am off to remove the death loo from stormy this week and am going to try and fill the through hull at the weekend. The loo is just bolted to a moulded hole with no skin fitting and has a large diaphram covering the entire seat ! I also intend to do the same job on the sink through hull.

Ideas on how to fix the hole are greatly appreciated. My vauge idea is to put 3 layers of glass mat (epoxy) over the top of the hole and then back filling from the outside with epoxy/silica mix.

Cheers

James
1:25PM, 14 November 2011 PDT (permalink)

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farmer boy says:

I have a copy of "this Old Boat" which has all the info you need... send me your email address and I shall send it to you..
94 months ago (permalink)

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Super Snoopy 050 says:

I have found that Isopon P40 is the best thing since sliced bread to fill holes and build up structures in GRP. It's chopped fibres in a polyester resin and is stiff enough to stay put, wherever you stuff it. Obviously it has to be overcovered with mat with epoxy as the outermost layer. Don't be too put off by polyester resin - the whole boat's made of it!
94 months ago (permalink)

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Skykomish E29 says:

"This Old Boat " book certainly does explain what to do very well, considering that failure to do this job properly could result in your boat making an unwelcome trip to the "green room" I would suggest that you follow the advice in the book closely. I successfully filled two holes in the bottom of my Skipper 17 doing the job the way it was described in the book and never had a problem afterwards.
You will need to grind back the hole in a progressive "dish" so that the edges are feathered then build up with layers alternating in GRP mat and Roving. On the inside as you can get to it you will need to abrade the surface surrounding the hole and cover over with matting.
On the outside finish with either epoxy marine filler or gelcoat filler making sure that you stick a sheet of plastic over the surface before it sets, then remove once hardened, this will ensure a smoother finish with less sanding. You will understand why this is helpful when you try and sand hardened gelcoat filler... it is a B*****d to get smoth
94 months ago (permalink)

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welkman001 says:

have had a look. Here is my plan:

Remove mounting block from hull and grind the inner hull out to a 12:1 bevel around the ols sea cock hole. Place a bit of plastic over the external hole, painting with release wax. Using epoxy, cut out mat to size and layup large to small from the inside. Wait for it to go off, grind flat, then add a nice large square over the whole thing on the inside.

Some questions. What do I need to do on the outside of the hull to get a good finish? how does gel coat come into it? What is the difference between grp mat and roving?

Sorry I might be a bit slow here, I have only ever worked with epoxy before and seem to be getting confused with the instructions !

Cheers
94 months ago (permalink)

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welkman001 says:

oh and how thick is the hull forward of the main bulkhead
94 months ago (permalink)

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Andrew Curry says:

Hi

I would use epoxy for these repairs. This manual might be off help

www.westsystem.com/ss/assets/HowTo-Publications/Fiberglas...
Originally posted 94 months ago. (permalink)
Andrew Curry edited this topic 94 months ago.

busy home [deleted] says:

Keep away from wax if you want the glass to stick.
Work from the outside in WARM conditions
The hole should have the large part of the chamfer outside to make a mechanical plug. IE you cannot push the plug in to the boat even if the glue failed!
Do not expect to smooth the hull fair . leave a bump.
As its under the water who sees it?
Isopon fill agap (strands is ok)
Use an angle grinder with a pad to smooth the rough bits,
Then do the matting bit inside ,
The hull is 13mm
I would wait till a warm day in the summer to do it.
94 months ago (permalink)

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songeur2010 says:

I had decided to install an electric toilet into Songeur, (might help encourage the wife to come sailing).
I've posted a photo of the plugs cut out in the process of fitting skin fittings.
I would do as chille pepper says, grind chamfer on out side, put some wide tape over hole on inside and then layer up with epoxy and chopped strand mat. Make ever increasing size circles of mat as you work your way out to match the diameter of the chamfer at each thickness point. Apply peel ply over last flush layer and you will hardly need to do any finishing work once the repair has gone off and peel ply removed.
You may need to support the patch until it gells off to stop it slumping, you could use a a small piece of plywood with a prop, make sure you've got a bit of plastic film between the ply and patch to stop it sticking. Hope that helps.
93 months ago (permalink)

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Skykomish E29 says:

GRP mat is the "Stranded" straw like matting that most are familiar with, roving is like a woven cloth. The strength comes from the combination of these materials, the random strands of GRP mat, the vertical and horizontal weave of Roving..
All of this sounds very complicated however once you get down to the job it is really easy, especially as you have access to both sides.
93 months ago (permalink)

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welkman001 says:

but with epoxy you just need mat not cloth right?
93 months ago (permalink)

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Skykomish E29 says:

mmm not sure about using epoxy to repair I had read somewhere that it is not a good combination.. to repair GRP polyester resin with Epoxy on large holes it is something to do with the way the chemistry works and the repair process, using polyester resin on a polyester constructed boat tends to make a better bond, in that you are using the same materials that were in the original construction, however I am sure many will disagree and not being a specialist in GRP repairs leave it for you to decide
93 months ago (permalink)

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songeur2010 says:

As explained to me by the boat builder who help me through my repairs, you can use epoxy over or to repair polyester not the other way around, you could also use vinylester but this needs to be post cured with heat.
Epoxy and vinylester are both impervious to osmosis, modern polyesters are probably better that the 1975 variety. Having tried all three for various tasks on Songeur I now would stick with epoxy for all repairs, large or small.
93 months ago (permalink)

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songeur2010 says:

Just use mat as you can get nice heavy weight product which will mean less layers. The main boat layup appears to have a heavy roving layer but definitely not necessary for a small repair like this.
93 months ago (permalink)

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welkman001 says:

cool sorted now. Will get some epoxy as I need to add some reinforcment to the cockpit sole as well.
93 months ago (permalink)

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reactiveresins says:

if you are looking for epoxy resin, may i suggest our website www.resinstore.com

Epoxy resin packs are available in 1.5kg, 7.5kg and 37.5kg packs
93 months ago (permalink)

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