Lightest, Cheapest, Fastest To Assemble Panels?

Discussion in 'Materials' started by oceannavigator2, Apr 18, 2014.

  1. oceannavigator2

    oceannavigator2 Previous Member

    I have a few non structural partitions to make up to wall off lockers, heads and make stateroom doors.

    Ant tips on the lightest weight, cheapest and easiest/fastest assembling material to use for this? A good surface is required. This is the interior.
     
  2. PAR
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    PAR Yacht Designer/Builder

    Lightest is often in direct contradiction to cheapest (carbon and Kevlar aren't cheap). Easy and fastest assembly also conflict a lot of times, particularly if developed by someone with limited engineering or building experience. The cheapest will likely be plywood, though cored panels and/or with exotic fabrics will be lighter. The lightest, well this is just good engineering inventiveness, which appears to be lacking on this project. This is one of the key elements of a good engineer - employing the right combination of materials and methods to get cost effective, light weight panels. I'm not trying to insult you, but considering your previous questions, I think you're in over your head. Maybe it's time to hire an engineer, to provide some options and possible solutions to your requirements. I'm currently working on a semi custom version, of one of my designs and have just completed the new cabin structure, which is thin plywood (sandwich) over a foam core, making a fairly light, reasonably cost effective, very strong structure. I was a logical route, considering the rest of the build, the skills and resources of the builder and of course the budget. Welcome to engineering 101, where learning to jump through multiple hoops, without touching too badly, is the usual technique.
     
  3. oceannavigator2

    oceannavigator2 Previous Member

    Thanks, PAR. I'm not an engineer, obviously.

    The majority of the boat is done already and was designed by a famous person.

    Now we are onto just a few customizations and a steep drop in available funds for fit out. The boat is very weight sensitive, but there is little money left.

    A little inventiveness is needed to finish the odds and ends that don't matter structurally. Ie: Partitions between structural bulkheads, cabinetry, those davis, which are aluminum now and paint.

    Other than that, the structure is done and systems design and installation is my specialty.

    I was onto the cheap, extruded polystyrene with glass skins as a candidate, very thin, 3/16" plywood with framing instead of foam, or the plywood skinned foam you were just mentioning.

    I wanted to make sure there wasn't a technique or material I had overlooked.
     
  4. alan white
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    alan white Senior Member

    1/4 lauan plywood is light. It costs very little from a box store. It is easy to deal with.
    You should test it first for water-proofness. Then it should be sealed, especially edges, with epoxy.
    As far as strength goes, at least for the intended non-structural use, depending on where and how it's used, you can stiffen it a lot by adding bracing disguised as trim at mid-spans. It has good surface characteristics in terms of paint and can even be left natural. A lot of panels are actually attractive if you like that sort of look.
    You asked for light, cheap and easy.
     
  5. oceannavigator2

    oceannavigator2 Previous Member


    I did the weight/cost analysis today and came up with this very same answer.

    Here is the data for 25 square feet of panel.

    Cheap XPS foam and 20oz glass is 13lbs and uses epoxy, plus needs coves

    Xps foam with 1/8 lauan is 19lbs, also higher cost, needs coves.

    A lauan/stick/lauan panel is 24 lbs.

    BUT, a lauan panel with a single face (an ugly side on the inside) is 15.5 lbs and screws together in minutes, tabbed or cleated to the hull. Far cheaper, no epoxy needed (just paint or clear finish), etc.

    A good idea.

    And before the naysayers come out saying I need to epoxy coat my cabinetry, I don't. I do not allow water inside boats at all. Dry bilges, certainly dry cabinetry. They'll last just painted.
     
  6. alan white
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    alan white Senior Member

    I would still coat with epoxy, and especially the edges. It won't cost much but you'll get more life out of paint over it and if you should happen to take in some water down low it will be money well spent. Still cheap.
     
  7. PAR
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    PAR Yacht Designer/Builder

    You don't have to "let water inside the boat" to have moisture damage. It's moisture vapor that's the big issue, not standing water. Of course, being on the water, there's lots of moisture vapor available to penetrate and permeate every wooden or absorbent materials aboard, without a drop of water touching anything.

    Lauan can can be had in several quite thin sizes, from 1/8" (3 mm) on up. Well built "stick frame" cabinets, skinned with thin lauan will be cheap, but can suffer from warpage and other moisture related issues, so the usual recommendation is epoxy. An initial sealing coat, plus two over coats if finished bright or a single over coat if to be painted. You can even tint the epoxy, so you can even the color under the over coats or use it as a translucent coating under clear, showing some grain and some color. These panels can also be skinned with vinyl, maybe padded, possibly button tuffed or tuck and roll for that cool 70's look. You can glue (contact cement) all sorts of things to these panels for about any decor you like. Maybe stainless or chrome looking Mylar sheet or copper sheeting, or leather, the only limit is your imagination. There's even "printed veil" products to simulate many surfaces, such as granite, glass, marble, wood, metals, camo, even bubbles or pebbles.
     
  8. rwatson
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    rwatson Senior Member

    I haven't heard much back from the US about the state of their Pawlonia industry - but you may get lucky via their national organisation

    http://www.paulowniatrees.org/links.htm

    The timber is very light, it reminded my of dense balsa - but it it virtually rotproof, attractive and strong.

    Like all quality timber, its not all that cheap, but probably saves on exotic materials and all the work and hassle of epoxies and fibres.
     
  9. nimblemotors
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    nimblemotors Senior Member

    which one? lightest, cheapest, or fastest can't have all of them. Not Strongest too?
    Maybe just ask for the 'best' one instead? :)

    Consider PVC 4x8 panels, not really '..est' of anything, maybe 'easiest'.
    http://www.interstateplastics.com/foameD_srch.php
     
  10. PAR
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    PAR Yacht Designer/Builder

    Really, PVC. A 1/4" thick 48"x96" panel for $70 bucks, that isn't tolerant of much heat without huge movement, can't be glued, though can be welded, requires a support structure, etc., etc., etc. It does make a good sign to hang on a wall. Plywood is the cheapest and easiest to use and it's self supporting if the seams are taped.
     
  11. nimblemotors
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    nimblemotors Senior Member

    Yes REALLY. Plywood was already suggested, maybe you don't pay attention??
    <removed>
     
    Last edited by a moderator: Apr 21, 2014
  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Yes, I suggested plywood in the second post on this thread, so maybe someone isn't paying attention . . .
     
  13. Steve W
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    Steve W Senior Member

    I would definatly epoxy seal all plywood but you don't need to go the full monte with 100% solids. Thin epoxy is much cheaper, easier to use and perfectly adequate for interior work. I have been using thin epoxy for 30 years from E bond epoxies in Ft Lauderdale. You do want to use 3 coats but it goes on like water with just a light hand sand between coats.

    Steve.
     
  14. cluttonfred
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    cluttonfred Junior Member

    Off the top of my head, MDO (medium density overlay) plywood as often used for signs would work well for non-structural partitions. It has a nice, smooth finish and will do just fine if edge sealed with runny epoxy. $38 per 4'x8' 3/8" sheet.

    Otherwise, for something even lighter, find the lightest, cheapest doorskin plywood you can find (~1/8") and make a plywood/foam/plywood sandwich with epoxy over 3/4" or thicker rigid polystyrene foam insulation boards. Seal those edges (ply and foam) with unthinned epoxy as you don't want any added solvent to melt the foam.
     

  15. nimblemotors
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    nimblemotors Senior Member

    Right, PLYWOOD requires a lot of preparation to use on a boat, you don't buy a sheet and just install it. Hmm, if only there were a material that didn't rot and didn't need sanding or coating, hmm, what might that be?
    Something you can just buy and cut to shape and put in place and be done,
    doesn't even need paint and has a good textured finish? Hmmm... oh I give up, there must not be anything easier or faster than PLYWOOD.
     
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