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Author Topic: Waterproofing and finishing a yacht hull  (Read 267 times)

Arakerr

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Waterproofing and finishing a yacht hull
« on: October 30, 2018, 12:00:17 AM »

Just about to start an Aeronaut Bella build. Never built a wooden yacht before. What is the best way to waterproof and finish the hull. I would like to keep the natural mahogany wood finish rather than painting the hull above the waterline.
I was going to use west system laminating epoxy, however there seems to be issues with a varnish finish not curing over an epoxy finish. Am I best to use epoxy on the inside and use varnish on the exterior only or has anyone had any experience of using varnish over an epoxy base coat. I believe it should reduce the number of coats of varnish required to achieve a mirror finish if compatible products are used. Any advice would be very much appreciated. :-))
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grendel

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Re: Waterproofing and finishing a yacht hull
« Reply #1 on: October 30, 2018, 06:59:00 AM »

I used zpoxy with a 25g fibreglass cloth, you cant see the cloth after, so get a good sealed hull and planking showing.
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roycv

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Re: Waterproofing and finishing a yacht hull
« Reply #2 on: October 30, 2018, 08:36:16 AM »

Hi all, my Bella has the advantage of strengthening the hull on the inside especially at the joints at the chines with a glass fibre cloth and yacht varnish on the mahogany finish on the outside.
I apply varnish on the deck with a cloth over a finger this means it goes on thinly dries quickly and leaves no brush marks.  The hull comes up nicely with varnish rubbed down wet and dry etc.
I would suggest that the visible part of the keel is very thin for a yacht and that it be sandwiched between more 3mm ply and then sanded to a streamline section.
There is more on this forum regarding building Bella.
regards
 Roy
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Arakerr

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Re: Waterproofing and finishing a yacht hull
« Reply #3 on: October 30, 2018, 09:34:37 AM »

Thanks for the advice. Can I confirm Roy that you increased the strength on your Bella with 2x 3mm ply either side of the keel and did you do this after the hull sides were glued in position to the main frame work.
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JimG

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Re: Waterproofing and finishing a yacht hull
« Reply #4 on: October 30, 2018, 11:18:35 AM »

Instead of laminating epoxy use the brushing epoxy used on planes for skinning wings. Even without the fiberglass skin it will allow you to produce a good finish. On wood I like to add some microballons to the epoxy, this gives a colourless filler which sands to give a smooth surface. If you use at least two coats of epoxy you can produce a finish which can be polished to a shine and doesn't need any varnish.
Jim
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dreadnought72

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Re: Waterproofing and finishing a yacht hull
« Reply #5 on: October 30, 2018, 11:25:18 AM »

I was under the impression that epoxy degrades when exposed to UV, and that a UV resistant varnish over exposed epoxy was the best way to preserve brightwork (and the structure!)


Andy
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roycv

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Re: Waterproofing and finishing a yacht hull
« Reply #6 on: October 30, 2018, 11:41:58 AM »

Hi arakerr1, I actually used obechi but it is the strength you want.  If you reinforce with ply as you sand it down you pass through the laminations and ths gives you a good idea of symmetry for each side.
When gluing put some extra wood either side and use screw clamps not spring ones.  You get a much stronger joint if it is screw clamped, the wood spreads the load and prevents marking the surface.
Regards ,Roy
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john mantova

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Re: Waterproofing and finishing a yacht hull
« Reply #7 on: October 30, 2018, 08:50:43 PM »

Use Ronseal Varnish either Water based or spirit based No epoxy needed. There are a load of others if you pop onto a planes forum and ask there. A good yacht varnish is as good as any. Creases from folded cloth can be pulled out by pulling over the top of a door or table edge with a see saw action for a bit under tension. Steam may help if stubborn.
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