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Author Topic: What to use to waterproof a ply hull  (Read 6556 times)

markrider

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What to use to waterproof a ply hull
« on: January 18, 2016, 11:10:17 am »

Hi I'm building only my 2nd scratch built boat. The first one was balsa and just painted it to seal the wood.
But am thinking is there anything else that people fund better that just paint as it did start cracking after a bit.

Many thanks
Mark
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canabus

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Re: What to use to waterproof a ply hull
« Reply #1 on: January 18, 2016, 11:48:18 am »

Hi Markrider
I fibre glass resin my boats inside and my first balsa hull I did the same on the outside, but, it is very easy chipped off.
Fibre glass resin with a stocking or woven fibre glass matting will be stronger.
My last boat was all plywood except for part of the bow I used balsa(Sea Hornet).
My next project is all plywood and with brushless motors and Lipo battery power and speed is no problem.
The little Sea Hornet pulls about 40mph.
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roycv

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Re: What to use to waterproof a ply hull
« Reply #2 on: January 18, 2016, 01:35:24 pm »

Hi, I always smooth down the ply with sandpaper.  Then a varnish thinned 50 : 50 this will go into the wood and dry quickly.  Treat the inside ply the same.  Another coat and then a little wet and dry to take the roughness out.  Then slightly thinned varnish, wet and dry then more 2 or 3 times or more and you should have a nice surface for colours.

I have models done like this probably with 10 coats of paint sometimes more but they just need a clean up after use and the finish is still good after 30 years.
You should try and balance what you do on the inside of the hull so that no water can be absorbed and get into the wood.  This will get behind the outside paint and it will crack as the temperature changes 'move' the wood.

When I come to deck planking I do not use a brush, I make a cloth 'rubber' wrapped around a finger and rub the varnish in.  This way you do not get any brush marks or over thick varnish.
regards Roy
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Peter Fitness

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Re: What to use to waterproof a ply hull
« Reply #3 on: January 19, 2016, 04:52:31 am »

I always use fibreglass resin inside and outside all my wood boats, and add some fibreglass matting around the chines inside for extra strength. When rubbing the outside of the hull down, I use wet and dry paper wet, otherwise the heat caused by rubbing can make the resin "ball" up. I then use multiple coats of spray primer-filler, well rubbed down between coats, followed by an undercoat then the top coat, usually acrylic enamel.


Peter.
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coolbumble

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Re: What to use to waterproof a ply hull
« Reply #4 on: January 20, 2016, 12:01:17 am »

Hi Mark
I had this "newby" problem with a wooden boat when I purchased a mahogany hull.
If you go to the forum under GRP and EPOXY item "WATERPROOFING A MAHOGANY PLANKED HULL" by coolbumble (me) February  14Th  2015 you will find plenty of info from members and pictures of what I finally did which proved successful.
I'm posting a picture of the boat near completion before installing the steam boiler etc.

My regards
Ian  :-))
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markrider

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Re: What to use to waterproof a ply hull
« Reply #5 on: January 20, 2016, 08:32:30 am »

Great that's chaps
Thanks Ian will take a look

Mark
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barriew

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Re: What to use to waterproof a ply hull
« Reply #6 on: January 20, 2016, 09:10:36 am »

Mark


As an alternative to polyester resin and fibreglass tissue or mat, I sometimes use EZE Kote resin which is water based and easier to apply and clean up. I usually use this with model aircraft tissue, although I have used glass tissue as well. This is what I used on my Rhum, and also on my current build.


Barrie
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markrider

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Re: What to use to waterproof a ply hull
« Reply #7 on: January 20, 2016, 10:51:37 am »

Hi Barrie
I herd of that seems good. Easy to out on ?/
Where did you get it from ?
Mark
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barriew

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Re: What to use to waterproof a ply hull
« Reply #8 on: January 20, 2016, 01:26:13 pm »

Yes Mark. In this weather, unless your workshop is centrally heated, its much easier to put on. Doesn't thicken up with the cold. Any model shop selling Deluxe Materials should have it - its used by the aero modellers, or if you need to buy online, this is the cheapest I could find on ebay http://www.ebay.co.uk/itm/Deluxe-Materials-Eze-Kote-Laminating-Finishing-Resin-500ml-Modelling-material-/291655456885?hash=item43e8051875:g:M6oAAOSwd0BVzIRv


Barrie
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markrider

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Re: What to use to waterproof a ply hull
« Reply #9 on: January 20, 2016, 01:54:07 pm »

Thanks Barrie do you need matyingbas well to go with that
?/
Mark
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Crossie

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Re: What to use to waterproof a ply hull
« Reply #10 on: January 20, 2016, 02:02:48 pm »

Mark


As an alternative to polyester resin and fibreglass tissue or mat, I sometimes use EZE Kote resin which is water based and easier to apply and clean up. I usually use this with model aircraft tissue, although I have used glass tissue as well. This is what I used on my Rhum, and also on my current build.


Barrie

           Yes Mark , I also use this stuff on all manner of projects, on wood, foam, thin glass cloth. Really useful for modelling and as Barrie says easy to clean up, no hazardous fumes, not as strong as other resins though but easy to work. Also easy to colour with artists acrylic paints.

                              Trevor
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barriew

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Re: What to use to waterproof a ply hull
« Reply #11 on: January 22, 2016, 11:28:48 am »

Sorry - trying to edit a post causes all sorts of strange effects. See next post


Barrie
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barriew

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Re: What to use to waterproof a ply hull
« Reply #12 on: January 22, 2016, 11:29:44 am »

Mark

Only just seen this message - whats this? matyingbas

Barrie

Barrie
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