(strip)planking a Wharram TEHINI ?

Discussion in 'Multihulls' started by Islander63, Jun 15, 2022.

  1. fallguy
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    fallguy Senior Member

    The best way to build in the tropics would be epoxy and foam unless you can control the climate a bit. It is outside my expertise as to how it is managed.

    @rxcomposite is in the Phillipines...it would be good to hear from him as to how builders manage environment

    Ultimately, the boat you build will depend on the build environment. It is nearly impossible to build a massive boat in epoxy in high heat.
     
  2. Rumars
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    Rumars Senior Member

    Varnish is a bad idea, but the wood is not really a problem, drying is done in the tropics all the time. Natural air drying will result in ~16%, from there you need some form of climate controlled drying. A solar kiln can dry to 8% in the tropics, the question is what you do with the wood afterwards. This also applies to plywood, for best results you keep it wrapped in plastic or in a climate controlled room (dehumidifier or air conditioning). Once installed it's coated in epoxy anyway, so that's not a problem anymore. The short time it spends exposed during working is fine, it won't suck moisture instantly. Remember, this are best practices, people have been building in the tropics without those precautions and ended up with a solid product.
    I would simply buy air dried local wood, for example jackfruit, mill it slightly oversize and give it some time in a basic solar kiln.

    The resins are a different problem, and this applies regardless if you use wood or not. You have to ask the manufacturer how they react to your temperature and humidity and follow their instructions. For example heat can be managed with ultra slow hardeners and small batches. A lot of epoxies tend to exhibit increased amine blush at high humidity, so you may have to wash all dried epoxy before continuing working. UV can be managed by simply covering the parts until painting.
    Polyester&Co have their own requirements for your climate.
    Composite boatbuilding should ideally be done in a climate controlled building, but that doesn't mean outside in the tropics is impossible.

    As for the design, that's a personal thing. If the Wharram fits the bill, why not? It's not like there is one single universal "best boat". As I said, for a flat planel boat, double diagonal makes more sense than strip planking, but that's also a personal choice.
     
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  3. fallguy
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    fallguy Senior Member

    I didn't mean to be a joy killer. Building a boat is a great experience. There are certainly environmental challenges to overcome. Not knowing them makes it much worse with lotsa costly learning. So, dare to pursue it with the constraints.

    Have you considered harry proas?
     
  4. Islander63
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    Islander63 Junior Member

    As Fallguy mentioned it would be better to build in foam/epoxy in my climate, makes sense to me because nobody here is working with wood as core except for transoms. Also they use mostly Polyester resin pouring in molds, or if they have to make a one-off piece, honeycomb or foam with thick glass fiber and poly. resin.
    Usually heavy and ugly, but boats build here are mostly for functional purposes.
    I have found a picture of a Tehini build in divinycell ??. will try to send as attachment. (call me what you want but she is a beauty)
    Never really considerd Harry Proas. Have to look in to it.
    I thank also Rumars for the good explanation about wood drying and trying to manage humidity in the tropics.
    So just building outside under a tarp storing the material (plywood) in a container would be unwise because it could accumulate moisture and once encapsulated with epoxy it will rot. He also mentioned " A lot of epoxies tend to exhibit increased amine blush at high humidity" but i don`t know what that means.
    I have never looked in to building with a foam or "divinycell" and epoxy. Maybe it`s not a bad idea, i mean if i have to import core-material anyway, a foam soort would be much cheaper when it comes to transportation alone.
    I have to look in to this option. It could be the answer to my dilemma living in the tropics, lol.
    Again thanks to you all for brainstorming with me.
    Cheers islander63
     
  5. Islander63
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    Islander63 Junior Member

  6. fallguy
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    fallguy Senior Member

    You can build a door on the end of a shipping container and climate control it with a small ac unit set for like 85 F.

    Amine blush is a grease like substance that occurs in the reaction of certain epoxies under certain conditions. Some epoxies are more prone to it. I don't know the chemistry. But if it happens, warm soapy water removes it. If not removed, the next later of epoxy will not bond to the substrate.
     
  7. redreuben
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    redreuben redreuben

    If you going the foam route epoxy is overkill and overspend, vinyl ester gives much better value for money and is much quicker and easier to use.
     
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  8. fallguy
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    fallguy Senior Member

    true
     
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  9. Islander63
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    Islander63 Junior Member

    I am not sure but i have to find out the technics of how to use it. I have seen discussions about foam vs. ply on this forum. It would most properly be lighter, but not faster to build.
    Also i don`t know what glass mat to use than etc. But it sounds good to me at least i won`t get problems with high humidity, storing and building. And no rot after.!
    Are there any good sites to find out more how to work with foam, and what products to use etc.?
    Also thanks to Fallguy for the explanation
    Regards islander63
     
  10. redreuben
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    redreuben redreuben

    For a project of this scope you would have a fair chance of getting some technical support from a supplier.
    “Technique” for vinyl ester is same as polyester.
     
    Last edited: Jun 18, 2022
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  11. fallguy
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    fallguy Senior Member

    Honestly, I'd build in ply. Build a small building to keep climate controlled. Build can be fast; start in the driest seasons, encapsulate it.

    or buy a good used cat and enjoy it
     
    Last edited: Jun 18, 2022
  12. bajansailor
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    bajansailor Marine Surveyor

    An excellent point - @Islander63 is the building process going to be as important to you (or even more important) than the sailing aspect when the boat is completed?

    If not, then it will be much cheaper in the long run to simply buy a second hand cat in good condition, and go sailing.
     
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  13. rob denney
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    rob denney Senior Member

    In my experience:
    Foam/glass would be lighter than ply for the same important properties. Infused foam glass will be much lighter, less messy, require less fairing and edge treatment and is effectively maintenance free.
    Building full length pieces of foam/glass is much easier than scarfing or butt blocking ply, especially when the ply gets heavy.
    Building over frames and stringers will add months to the job and result in a cluttered interior. Infusing 2 self aligning hull halves with joins, window and other rebates, local strengthening, solids for fittings, holes for masts and beams and landings for bulkheads will save you a lot of fit out time, fairing and finishing. As will making the rest of the boat from flat panels. see attached
    Vinyl will be cheaper than epoxy, but be careful with secondary bonds. It also stinks and messes with your brain. Epoxy messes with your skin. Treat them both (and any dust you generate) as toxic.
    Unless you are using polyester you will not need csm backed material.
    Carefully buying second hand will be cheaper than building new, but building smart will result in a more suitable boat, less maintenance and fewer things to worry about.

    Fallguy,
    Thanks for the referral. Amine blush is another reason wet laminating is effort intensive. For most epoxies, warm water and a scotch brite will remove it (keep the water away from the edge grain). If you use soap it must be removed (scotch brite and lots of water) or it has the same effect as the blush. Nothing sticks to it, and/or paint orange peels. Peel ply is a far better solution, although not suitable for coating unglassed ply.

    Building anything sizable in a container, even with air conditioning, is frustrating. Screenshot 2022-06-19 at 4.56.00 PM.png

    http://harryproa.com/wp-content/uploads/2022/06/C50-General.pdf.
     
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  14. Islander63
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    Islander63 Junior Member

    Fallguy and Bajansilor "I hear you" and appreciate the advice, and believe me i would go for a second hand, but apart from that mostly all used cats here are those huge bulky old models as Lagoon, leopard nautitech etc., they are also heavily overpriced. For years i am working here fixing mostly charter cats of all sorts. Mostly electronics and interior not so much mechanical. Therefor i have seen boats here, a surveyor like Bajansailor, would jump as quick as possible off board !!
    I`ve looked at a few Lagoon 470 witch where for sell at prices comparable to an average good offer in the US or South Africa. The state those are in, you would almost cry. Majority of Boats here are pure functional. Maintenance very poor often with wrong materials etc. A charter boat here, is like a cow being squeezed for milk as long and as much as possible. Then there are the private luxuries boats often maintained by foreigners contracted from abroad. And way over my paygrade.
    I think i don`t have much choice, and i don`t feel like importing a cat from SA or so.
    Regards, Islander63
     
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  15. Islander63
    Joined: Jun 2022
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    Islander63 Junior Member

    Hi Rob, thanks to i think it was Fallguy, who pointed me in the direction of Harryproas, that i got interested.
    But why is your site (harryproa.com) not accessible for me ?? First i thought may the site is just down, but i see on google etc. links to it ??
    Maybe it`s me. A bit old school when it comes to the digital world, so pls bare with me.
    I would like to find out more about your designs and building techniques. They are a complete different approach, for a live-on-board, but why not.
    I mean i might be old school, but i am not stuck in the past, just a bit slower i think. lol.
    Pls advice how i can get more to know about you and Harryproas.
    Thank you for your interest. regards islander63.
     
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