Newbie asking for advice

Discussion in 'Multihulls' started by jmoropeza, Oct 17, 2021.

  1. redreuben
    Joined: Jan 2009
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    Location: South Lake Western Australia

    redreuben redreuben

    Strip planking does not have to be slow, by keeping stock square on a round hull you get a natural V, on flat panels cut that same V onto the edge of the stock.
    Plank it up unglued and then squeegee the lot in one go, sand and glass.
     
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  2. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    I saw an Aussie leave a purposeful gap once.
     
  3. Will Gilmore
    Joined: Aug 2017
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    Will Gilmore Senior Member

    Hello jmoropeza, welcome to the boat design forums. I really like the thought and research you are putting into your project. You will make a great fit to the amazing group of builders, designers and boat lovers on this sight.

    I don't know nearly as much about boat building or boat design as most of these guys. I'm a cabinetmaker/artist that loves boats. I do know that marine grade plywood can be made if commercial sources aren't available, but it requires the ability to make or buy veneers. I have zero knowledge of foam core construction.

    In your place, I would be looking at cold mold wood construction. upload_2021-10-18_5-12-49.png
    It is strong and local woods would work.

    If you are looking at marinas in the Yucatan that allow boatwork, have you checked with them for their source of plywood? Maybe you simply drive to Houston Texas in a van and buy it there? If you aren't buying for resales, do you need to pay the tax?

    It's good to have you join us. I'm looking forward to following your project.
     
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  4. redreuben
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    redreuben redreuben

    I saw that, makes no sense to me.
     
  5. fallguy
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    fallguy Senior Member

    He was filling it all with thickened resin. I can see where the method you prescribed would have the potential for poorer bond strength if the glue doesn't bottom out is all.
     
  6. redreuben
    Joined: Jan 2009
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    redreuben redreuben

    IF. The alternative being grinding off big gobs of glue off the inside of the boat.
    And the shop floor. But we digress.
    People work out methods that suit them best, let’s leave it at that.
     
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  7. fallguy
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    fallguy Senior Member

    Yeah, the big gobs of goo part is equally horrible.
     
  8. rberrey
    Joined: Oct 2010
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    Location: AL gulf coast

    rberrey Senior Member

    You can contact Gruit Mexico for corecell foam , you will not find H80 or corecell foam for $20 a sheet . you will most likely need a glass in the 30 oz range , Quadxcial 3508 as an example , or 17 oz 45/45 with 18 oz 0/90 , probably won't need the mat , ask the designer or do the math yourself .
     
  9. guzzis3
    Joined: Nov 2009
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    Location: Brisbane

    guzzis3 Senior Member

    Sigh.

    There are 2 issues.

    1. Cost of materials. This varies from place to place. I have been buying foam, glass and bagging supplies from china. I get the epoxy locally. I can build a panel of 12mm 80 kg/m^3 with 600 gsm 45/45 each side vacuum bagged resin infused with epoxy for about $45AU sqm.

    _YMMV_. Let me type it again for emphasis. YOUR MILAGE MAY VARY. Got it ? I don't get a commission on the stuff. I couldn't care less if the OP builds in chined ply, cold molded or layers of tinfoil. He said he has trouble finding cheap ply. It's easy to say he should do this or that but unless you can offer a certain source at an affordable price saying this or that is cheaper doesn't help. _I_ can't buy 9mm ply that's good enough coat it in epoxy glass one side for $45/m^2 let alone do the extra framing.

    2. Build methods. No one builds cold molded anymore because it takes too long and probably costs too much. If the OP can't find good ply can he find strip ? I love strip but here it would cost me more than twice foam. I don't love it that much. Unless he solves the ply problem cold molded and chined ply are both uneconomic. Ply would have to be far CHEAPER than foam to choose it. With a table you can lay up full length panels in one hit and just fillet and tape them together.

    But all that is moot anyway. It takes 5 minutes to build a hull. None of this affects the cost and time to fit out, rig, power paint da da da da ...

    IMO what he needs to do is get reading. Get a realistic idea of what's involved and his options. Ask some more questions, make the choices that are right for HIM and then get into it, or not.

    OP: Yes you can combine different materials and methods on different parts of the boat. It is for example common to build rounded hulls in strip cedar to the waterline or so them plank the flatter sides and deck in plywood. It is common to build hull bottoms in solid glass and foam higher up. It's common to use foam to the shear and ply decks, beams etc. Personally I am over timber boats. I've owned quite a few and every one needed work. I'd rather be sailing but some people find timber a natural material to work or love the appearance. Make your own decision. Most of the common choices are good. None are perfect. Pick your poison once you understand the implications.
     
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  10. Richard Woods
    Joined: Jun 2006
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    Richard Woods Woods Designs

    Sorry to join the discussion so late, but I have been away sailing.

    I have cruised Belize and Guatemala (both coasts) and Mexico's Baja. We had our boat in the Rio Dulce one hurricane season. So I do know the area you plan to cruise. And since I have also spent a lot of time cruising in the Bahamas and circumnavigated the Caribbean Sea I also know where you plan to sail in the future. Incidentally, Russell Brown was, I think, the first cruiser to visit the Rio Dulce.

    So based on that I would strongly suggest the Gypsy over the Sango or Tamar. As I always say, buy/build the smallest you need not the biggest you want. The Gypsy can be built with foam or ply hulls and generally ply decks and central cabin, although a few have built in all foam sandwich. You can also build a round bilge strip plank cedar or paulownia hull but that's really for people who want to build more than sail. My own Gypsy had flat panel foam sandwich hulls and ply decks and central cabin. Launched in 1996 I last heard from the current owner in 2019, he had just come back from a cruise to Morocco.

    Electric motors and charging batteries have not yet reached the sensible option stage unless you are a true enthusiast. Finding a place to charge a car is hard enough right now (there are no charging facilities in the town where I live, for example, and we have on street parking for our car about 100m away from the house). And so totally impractical for a boat right now. Solar charging will take for ever to charge batteries.

    So hope that helps, and please email me direct on woodsdesigns@gmail.com to discuss things in private

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  11. rberrey
    Joined: Oct 2010
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    rberrey Senior Member

    Guzzis3 is giving good advice , 1st source and price material . China , Mexico . U.S wherever . Richard Woods always gives good advice and is always willing to give it , but do like Guzzis3 and price out your material per sq ft or meter ect . so you will know which option is right for you price wise .
     
  12. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Don't forget most builders fail to finish. The foam boat takes longer and is harder to build. Wet baghing has high supply costs and high epoxy wastage to make the boat light. If I had built a plywood boat bs foam, my time to water would have been 3 years versus 4.

    If you apply a dollar rate to an extra 1000 hours...
     
  13. rberrey
    Joined: Oct 2010
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    Location: AL gulf coast

    rberrey Senior Member

    There are many options when it comes to method and means , no reason to wet vac foam unless you are concerned about weight savings and maybe a 10% savings on epoxy use . Place the foam on a form designed for foam , about the same as plywood , and hand lay the glass and epoxy . A single layer of 30 oz glass on foam may take a little more time than a 6 oz layer on wood but I would think not much more , and you can average 40% to 60% epoxy to glass . I don't think a hand layup for a foam build will be much more time wise than a ply build in the total scheme of things . Source materials , price materials , see how big a boat you can afford to build , talk to Richard Woods and then decide on a boat , and what method and means best suit your situation and needs .
     
  14. fallguy
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    fallguy Senior Member

    You use more epoxy wet bagging; not less. There is not time to spare for tight use. I promise. Wetouts are never below 100% of glass weight, but the bag pulls it all out during the process. I actually experienced about 25% epoxy losses on my build to the bag and trimmings. We mighthave been closer to 110% wetout rates and 30% losses..

    30 oz glass will not wet down through and requires wetting the bottom side. So many things are not correct. Now, all that said, a foam build with all hand layup would not be as difficult, but there are so many caveats! The foam needs to be rigid enough or the jig does to support it or it must be table laminated one side first, etc. Foam is always going to be more complicated than plywood unless you buy pre-laminated panels which are then not cheap.

    The idea cheaper core is a cheaper boat is a massive fallacy.

    The last sentence is good, but I disagree with some of the post.
     

  15. fallguy
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    fallguy Senior Member

    I built a foam boat. Our epoxy use came in around 300 gallons @$100@ or $30,000. This is factual. A typical layup of 100 ounces of glass required about 110 ounces of epoxy for efficient bagging and to meet the core needs. We ended up with panels of about 54% resin.(corrected post 10/24). So, for a 100 ounce glass layup; a fair estimate of epoxy losses was 45 ounces! Of course, this was all vac table losses to build a quality boat. But if you have a budgetary concern; it must not be overlooked. I estimate epoxy losses to the bag of about $7500. That loss amount is enough epoxy to build many of Richard's ply boats.

    Let's make some assumptions. If you were laying 6 oz glass on plywood; that same amount of epoxy would be enough for 18 yards of fabric!!!

    For a comparison, a two sided foam layup of say 36 ounces glass for simplicity out to 110 ounces is about 3 yards with the bag losses.

    If you are concerned about time and $$ budget; foam is not it. If you are comcerned about weight; foam is it.
     
    Last edited: Oct 24, 2021
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