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Old 29-07-2011, 00:34   #1
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Painting a Hull vs ...er... Varnish ?

I was studying designs of gorgious strip planked sea kayaks and wondered why you never see a multi-hull that is just varnished ? I realize that sea water must be trying considering how often boats need to be hauled out for new undercoating but it seems like such a waste when I see someone build a cat from say, strip plank or stitch and glue and after all that sanding and glass work they PAINT it !! Almost makes me want to cry.

Even James Wharram designs which are south Pacific styled are painted. Surely the South Islanders didnt paint centuries ago ? Am I missing something about the corrosive nature of sea water ? Particularly warm sea water ?
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Old 29-07-2011, 00:52   #2
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Re: Painting a hull vs ...er...varnish ?

Due a similar philosophy, I just uncovered the wood in my mizzen mast and booms. Everyone was telling me how much a pain varnish is, but I have hopefully done everything right so it will cause me even less drama than paint. This included using an epoxy wood saturation treatment, which I put a dash of red tint in to bring out the beauty of the red oregan.

I was really impressed by the ease of the water based Bote Cote products I used. Now it is for the test of time!
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Old 29-07-2011, 01:32   #3
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Re: Painting a hull vs ...er...varnish ?

wow. Cool! epoxy wood saturation treatment. Sounds difficult to apply. Is it ? Looks like your boat has no keel. Would you attempt it below the water line or just on the upper ? Plans to slowly go down ? Love the red you chose on the upper. Gorgious.
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Old 29-07-2011, 01:41   #4
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Re: Painting a hull vs ...er...varnish ?

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Originally Posted by adamskiinasia View Post
wow. Cool! epoxy wood saturation treatment. Sounds difficult to apply. Is it ? Looks like your boat has no keel. Would you attempt it below the water line or just on the upper ? Plans to slowly go down ? Love the red you chose on the upper. Gorgious.
The hull is steel so I have just done the mast.

No, the Bote Cote epoxy saturation treatment was a lot easier to use than other products like International's Everdure, which I used till now. Unlike other products it also contains UV stabilizers.

Unfortunately the photo of the boat is before it was re-fitted and repainted lighter. Coincidentally, I met a fellow cruiser yesterday who was telling me he was sure he saw my boat in Townsville years back with its hull painted black. He reckoned it looked great - very pirate like - and might even have photos.
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Old 29-07-2011, 01:52   #5
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Re: Painting a hull vs ...er...varnish ?

I might be going off topic but here goes. Obviously things exposed to outdoors and UV, especially boats as they get reflection as well, must need extra UV whatever. My question is this, car companies use basecoat/clearcoat systems so what if the "base" were clear as in a clear enamel then with 3 coats of clearcoat would that not be the same as using white as a basecoat ??

I used to do auto body work and am wondering how boats compare to cars. Seems to me, after the primer they would be the same ?
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Old 29-07-2011, 01:56   #6
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Re: Painting a hull vs ...er...varnish ?

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Originally Posted by adamskiinasia View Post
I might be going off topic but here goes. Obviously things exposed to outdoors and UV, especially boats as they get reflection as well, must need extra UV whatever. My question is this, car companies use basecoat/clearcoat systems so what if the "base" were clear as in a clear enamel then with 3 coats of clearcoat would that not be the same as using white as a basecoat ??

I used to do auto body work and am wondering how boats compare to cars. Seems to me, after the primer they would be the same ?
On the same line of thought, I am wondering as well why their aren't some better marine waxes for clear finishes. I know waxing my car around the ocean was something that has really made the duco last and prevented rust.
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Old 29-07-2011, 02:00   #7
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Re: Painting a hull vs ...er...varnish ?

wow, Surfer Shane. A water-based paint on a boat ? They have water-based varnishes in Japan , where I live, and I was amazed of the quality. Dry hard as well. Mind you Japan is one of the top countries for varieties of lacquers, doubtful they use it on boats (mostly fishing craft here). I find there's nothing like the feeling of first coat on the wood after all that sanding. Wood just comes alive. Seems like paint must be like burying wood ALIVE !
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Old 29-07-2011, 02:22   #8
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Re: Painting a hull vs ...er...varnish ?

Wow, your cars rust in Australia ? With your dry temps I always figured it was like Arizona, probably the easiest state to own an antique ! I'm a Canadian so ours is helped along by tons of salt dumped on roadways during the winter of course.
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Old 29-07-2011, 17:20   #9
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Re: Painting a Hull vs ...er... Varnish ?

A lot of multi's are built using epoxy and glass, which doesn't take UV so well. That's a possible reason they get painted.
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Old 30-07-2011, 07:34   #10
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Re: Painting a Hull vs ...er... Varnish ?

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A lot of multi's are built using epoxy and glass, which doesn't take UV so well. That's a possible reason they get painted.
Could you tell me what "doesnt take UV so well" means ? You mean someone would epoxy glass a boat and then NOT put 3 coats of clearcoat on ? Even automobile clearcoat has UV blocks in them. I'm completely ignorant of boats though sorry to say. What happens ? The varnish starts to peal like old paint does ?

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Old 30-07-2011, 07:51   #11
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Re: Painting a Hull vs ...er... Varnish ?

G'Day Adam,

Epoxy resins are broken down by UV radiation. When the structure of the hull depends entirely on the strength of the epoxy used in construction, taking chances with this sort of degradation would be foolish. It wouldn't just be an issue of "paint peeling off", but the bonds between glass and timber, and between the strips of timber themselves breaking down. This would have serious consequences in the strength of the hull.

I don't know how effective the UV shields in your "Clearcoat" are, but so far none of the clear finishes that are offered for marine use have proven very successful for long term usage -- and remember that we are talking about boats that have much longer expected lifetimes than automobiles. For instance, our strip-planked composite hull is now 21 years old and going strong... painted,of course. Down below (where the sun don't shine) the few areas of the hull that are not covered by joinery are left bare. One can indeed see the Western Red Cedar planking, but the structural e-glass that covers it isn't clear like a good varnish finish. Looks nice, though!

HOpe this helps you understand why these boats are painted.

Cheers,

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Old 30-07-2011, 08:18   #12
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Re: Painting a Hull vs ...er... Varnish ?

I"m no finishing expert but -

1. On steel (as in cars and steel hulls), lets not forget that all important "conversion coat". That's the one that goes on first which adheres to the bare steel and allows the color coat to stay put. Sort of like the primer which goes under most top coats.

2. Seems to me that clear finishes, like varnish and all the rest, needs to strike a balance between hardness and softness. Must be hard enough to take wear but - especially on wood boats - soft enough not to crack when the wood flexes.

My old woody is all paint except for trim and small areas where good old Flagship varnish is used. 8 coats minimum. Max UV blocking and used only on areas which get no foot traffic. Window trim, butterfly hatches, etc. Just finished redoing one of the butterfly hatches and it confirmed for me that a varnished hull is just nuts.

Did just see a short clip on you tube about a UV cured clear gloss top coat. Hadn't seen that before and don't know the suitability for exterior use.

Botton line is - doesn't matter what the finish is, it still needs to be maintained. The question is, how often does it need to be recoated, how easy is it to repair the occasional ding, how easy is it to recoat.

I've used Cetol DEK for the last couple years and it's an indredable product on bare wood. Not a "marine" product so inexpensive and easy to use.
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