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Thread: PVC

  1. #1
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    Default PVC

    I realize this is the wooden boat forum, but I know of a couple of guys who are building traditional wooden type boats out of PVC. They actually don't look bad. PVC even floats.
    I don't really like working with it. It's heavy, slippery, and very limp. When you saw/rout it, the dust sticks to everything. Unlike wood, it will crack/fracture in any direction. It'll really bend though. The 2 part glue is expensive, but it seems to work very well. It is available in 20'x5' sheets.
    Any of you engineers/experts got anything to say about it's properties that make it unsuitable for boatbuilding?

  2. #2
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    Default Re: PVC

    Fun facts about PVC, in no particular order:

    The specific gravity of PVC is about 1.4. Unless blown into a foam, such as the architectural trim products, it won't float.

    For its weight, PVC has very low strength and stiffness, so it's a very poor structural material.

    It weathers better than unfinished wood, so it can be useful for non-structural outdoor things.
    PVC is fairly impact tolerant, but is not nearly as good as the various grades of polyethylene. There are commercially available extruded profiles for rub rails and spray rails that serve well on work boats. They do weather, so they're not attractive, even by workboat standards for long.

    The PVC adhesives are one-part solvent glues. They're as strong as the material and easy to use.

    PVC is a good electrical insulator and does not corrode.

  3. #3
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    Default Re: PVC

    I have successfully use PVC tube for sleeving keelbolts thru damaged wood. I'm not sure if this qualifies as "structural".
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    Default Re: PVC

    I have used 1/2" CPVC tube, slotted lengthwise on table saw while mounted in my homemade jig, as a sail slug slide on a wooden mast. Not my idea - Dudley Dix used the same CPVC tube/sail slide system on his Paperjet 14. I also use short pieces of 1/2" tube for through deck/bulkhead fairleads.

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    Default Re: PVC

    I'd be concerned about the prolonged effect of exposure to UV and the elements.

    Rick

  6. #6
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    Default Re: PVC

    Quote Originally Posted by hanleyclifford View Post
    I have successfully use PVC tube for sleeving keelbolts thru damaged wood. I'm not sure if this qualifies as "structural".
    G-10 (glass-epoxy) tube is stronger and bonds better .

  7. #7
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    Default Re: PVC

    Quote Originally Posted by Bill Huson View Post
    I have used 1/2" CPVC tube, slotted lengthwise on table saw while mounted in my homemade jig, as a sail slug slide on a wooden mast. Not my idea - Dudley Dix used the same CPVC tube/sail slide system on his Paperjet 14. I also use short pieces of 1/2" tube for through deck/bulkhead fairleads.
    PVC pipe comes in a variety of wall thicknesses. Schedule 40 is widely available. Schedule 80 is in distribution. Dimensions, etc. at http://www.harvel.com/tech-support-specs.asp


    An application like this might benefit from a thicker wall. I used 1/4" (nominal)schedule 80 for Damfino's trampoline lacing points.

  8. #8
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    Default Re: PVC

    Just a post note to what has been said- This material is like a foam. It has small "bubbles" inside. I assumed the glue was 2 part. He's got some pretty fancy caulking guns layin' around. I was told it'l float, I haven't seen this for myself.
    I have concerns about its durability and abrasion resistance, but this is just a hunch. No facts to back it up. I've seen 2 of his boats, they were painted up nicely, with awl-grip I think. This should alleviate concerns of UV damage.
    Let me be clear on this. I'm not trying to sell this idea. Frankly, I have doubts/problems with it. I just wanted some input from those of you who might know more about its shortfalls.
    On the flip side- If you use plywood and saturate it with cpes, glue it together with epoxy, fiberglass it over, and paint it with epoxy paint, is it any more wooden or natural than let's say "trex" decking or pvc?

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    Default Re: PVC

    Do you have a camera?



    Steven

  10. #10
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    Default Re: PVC

    Not PVC, but I used some Trex on a coaming cap, for durability, no maintenance, and its slipperiness. Shots here: http://www.pbase.com/bartenderdave/coamrim Been in service for three seasons, and it holds up well and does everything I wanted. Sucks to bend, though, and has zippo structural integrity in thinner dimensions. Not recommended for anything but a facing like this coaming cap, or a support pad (for fuel tanks -- where it is killer). Could have done this in oak or mahogany as a three-part series of lams, but then there would be maintenance of brightwork on an exposed surface ...

  11. #11
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    Default Re: PVC

    I think we're confusing two materials here.

    Eddiebou seems to be talking about foamed PVC (PolyVinylChloride). A common brand of this is AZEK and it's used for architectural trim boards, where pine or other softwoods would traditionally have been used. In this application, its advantages are that it's dimensionally stable, doesn't rot and is easy to mill and takes paint fairly well. It is not as strong or stiff as the wood it replaces. For boatbuilding, foamed PVC would be too weak and solid PVC would be too brittle.

    TREX and cutting boards and Starboard are polyethylenes. Polyethylene takes a lot more abuse than PVC will. Whole boats such as canoes and kayaks and even larger outboards (Triumph) are molded of polyethylene. These boats are very tough, but heavier than other materials. Polyethylene has the advantages of being tough and low-friction and the disadvantages of being quite limber and hard to glue or paint. West G/Flex will glue polyethylene, but not nearly as strong as the bond that epoxies achieve on wood.

    Both PVC and polyethylene have good uses on boats, but boat planking isn't among them.
    Last edited by JimConlin; 01-15-2011 at 12:56 PM.

  12. #12
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    Default Re: PVC

    +1

    Ive seen photos of boats as described, interesting idea but the tech is not there yet...

    just to mention a few negatives,
    more expensive than pine, similar price per board ft. to cedar and...
    1; heavier
    2; not as strong/stiff
    3; not as good to work with (especially with edge tools that are so important to traditional boat building)
    4; does not flex with as fair a curve/takes bends to bad curves without complaint

    doesn not smell as nice when cut...

  13. #13

    Default Re: PVC

    yes, i am confusing it with , i think its called p t f e, tape & chopping board stuff

  14. #14
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    Default Re: PVC

    Trex is a composite of recycled polyethylene and sawdust, not just PE. Not a good structural material at all. In no way comparable to virgin HDPE, etc.

    PTFE is a totally different cat -- slippery as snot and hell to bond. Foamed PVC is completely different.

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    Default Re: PVC

    Quote Originally Posted by peter radclyffe View Post
    yes, i am confusing it with , i think its called p t f e, tape & chopping board stuff
    PTFE is also known as Teflon. It's used for very low friction bearings, plumber's tape and nonstick cooking pans. Cutting boards are generally of polyethylene (aka PE) and high density polyethylene (HDPE). There's also Ultra High Molecular Weight polyethylene, aka UHMW or UHMWPE. It's less expensive and good for bearings and things that get banged. Damfino's upper mast bearing is of UHMWPE.

  16. #16
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    Default Re: PVC

    Quote Originally Posted by JimConlin View Post
    PVC pipe comes in a variety of wall thicknesses. Schedule 40 is widely available. Schedule 80 is in distribution. Dimensions, etc. at http://www.harvel.com/tech-support-specs.asp


    An application like this might benefit from a thicker wall. I used 1/4" (nominal)schedule 80 for Damfino's trampoline lacing points.
    I believe I used Schedule 40 CPVC. I use Schedule 80 PVC tube & fittings to fabricate tarp frames for various things, like a freeze cover for gardenias and a "Cat House" for the wood/epoxy beach cat, but I haven't spied Schedule 80 1/2" at Lowes. So far the !/2" 40 works - the Cat went through a nasty 25 knot+ wind squall with sails powered up to YAH HOO! max and none of the slugs let go. But I will look for Schedule 80 next time around. Thanks for the heads up . . .

  17. #17
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    Default Re: PVC

    You won't find the Sched 80 in the big box stores. I recollect that I got it at a distributor that catered to the trade. 20 ft. lengths.
    Harvel is a major manufacturer. I expect they could tell you who distributes a particular product.

  18. #18
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    Default Re: PVC

    Check out Cockrell's marine railway pvc boats. just google it and see for yourself.

  19. #19
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    Default Re: PVC

    Quote Originally Posted by Eddiebou View Post
    Check out Cockrell's marine railway pvc boats. just google it and see for yourself.
    Had no idea about Cockrell. Thanks for the tip.
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  20. #20
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    Default Re: PVC

    I would use PETG or polycarbonate (Lexan). I used to make fishing flashers out of PETG, it's extremely tough, and unlike polycarbonate it doesn't absorb water. I does in fact have all of the qualities needed to build boats.

    http://acrilex.com/petg-the-often-unsung-hero/

  21. #21
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    Default Re: PVC

    weight. Look at the density compared to wood, and if you are going to build in PVC sheets it is worth while to get a calculated volume of materiel and compare that to the calculated weight of the boat built in wood per the designers spec. Could be twice as heavy.

    I did this exercise several years ago, no PVC boats for me at the scale I want them.

  22. #22
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    Default Re: PVC

    Bill are you sure about that? I thought he told me one of his clients used Flex A Rail. Costa Track PVC arming track is better than flex a rail for mast slug track.

  23. #23
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    Default Re: PVC

    Another alternative could be Revetement Agro, if you're still interested in PVC panels.

  24. #24
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    Default Re: PVC

    Azek is probably the material that the OP ran across. Azek sells adhesives and Plexus works on it. To quote myself from 5 years ago
    Quote Originally Posted by MN Dave View Post
    One thing that would concern me with these composite panels on a wooden boat is the big difference in the ways that wood and plastic move with thermal and moisture cycles. Coosa and Azek are the two somewhat wood like materials than can be used to build a wood like boat that I am aware of. Coosa is a PU and the Azek is PVC. I met a guy at the MASCF who has been building boats entirely out of Azek for ten years now. I dug up the tech data sheets on Coosa and Azek.

    The thermal expansion is about the same, roughly 30 ppm/F, which is about ten times that of wood. Moisture expansion is low for the plastics and high for wood. They will move differently, so large areas that are heavily constrained will tend to warp. Paint it a light color. The heat deflection temperature is higher for Bluewater 26, Nautical 20 is similar to most boat building epoxies, and Azek is right in the middle. The stiffness follows the same BW26>Azek>Nau20 trend, along with strength. They are all about as stiff as rotomolded polyethylene. So not a major concern, but will need more support than plywood.

    Adhesives are similar, Coosa has an adhesive page that recommences mostly acrylics. The 3M epoxies are not inexpensive, and are far better than West, MAS, etc. for bonding plastics. All epoxies are not created equal. Azek is probably not as easily glued with epoxy as Coosa, so you should stick with the acrylics and PVC adhesives mentioned on their data sheet. The Plexus adhesives are good for Azek. I would test an epoxy first on either of them, but Coosa should be more forgiving. Adhesives for Coosa should be more compatible with wood than the PVC adhesives.

    In a fire, the gas that will kill you is different.The end result is the same, but the details are different. When you don't finish the job, the recovery is easiest from wood smoke, and PVC smoke is the worst. Not the first thing that comes to mind, but always a consideration in any enclosed space.



    https://www.timbertech.com/webdam/do...azek_deck.pdf/
    https://azekexteriors.com/products/sheets
    https://www.timbertech.com/webdam/do...4/ESR-1667.pdf
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  25. #25
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    Default Re: PVC

    Quote Originally Posted by hanleyclifford View Post
    I have successfully use PVC tube for sleeving keelbolts thru damaged wood. I'm not sure if this qualifies as "structural".
    You could replace the entire keel bolt with a fiberglass bolt. The nuts have to be longer than with steel bolts because the shear strength in the cut threads isn't very high. No rust, no delignification, no one has apparently ever tried them.
    https://www.strongwell.com/wp-conten...BOLT-Flyer.pdf
    https://www.creativepultrusions.com/...ass-fasteners/
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