Novice fiberglassing pvc pipe needs help

Discussion in 'Boatbuilding' started by VictorVictor, Nov 20, 2015.

  1. VictorVictor
    Joined: Nov 2015
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    VictorVictor Novice fiberglass

    Help please!
    I am a beginner at fiberglassing.
    Before I begin repairing an old sailboat I want to practice on a different project.

    I have 4 ten foot lengths of schedule 40 PVC, slit and telescoped one into the other. Diameters start at 2 inches and reduce to 1 inch. After telescoping the overall length is 35 feet.

    I have secured 36 continuous feet of 10 ounce, 2 inch diameter sleeve fiberglass, which slips around the entire length of pipe. I also have enough epoxy resin with slow (60 minutes) hardener to reinforce the pvc pipe. The objective is to erect the 35 foot pipe into a vertical position once strengthened.

    I lack experience for the actual spreading of the epoxy in that the pipe completely enshrouded with fiberglass sleeve rests horizontally on 4 wooden sawhorses, outside. I am not sure how to proceed because of the following questionable alternatives.

    1. Can I apply epoxy everywhere except for the places where the pipe rests on the sawhorses? Then, after letting it harden, reposition the sawhorses, and apply epoxy to the now exposed former rest points?
    OR
    2. Can I apply epoxy to the entire upper surface of the pipe, let it harden, rotate the pipe 180 degrees so that the bottom and top are reversed and apply epoxy to the bottom (now upper) half?
    OR
    3. Position the sawhorses so that one end of the pipe is unsupported, epoxy that free end, let it harden, move the sawhorses with a new section now unsupported, epoxy that section… repeat this piecemeal epoxying until the entire length is epoxyed?

    4. Is there a better way to do this other than 1,2,or 3 above? Each one of those results in a place where the epoxy that just hardened meets fresh liquid epoxy being applied. It is the final strength of these intersections that has me worried.
    Ie: Is fiberglassing in 2 or more steps going to result in a strengthening as good as if I did it all in just 1 step?

    5. I cannot stand the pipe up (vertical) before fiberglassing.
     
  2. gonzo
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    gonzo Senior Member

    Your first problem is that the sleeve is 2" but the pipe reduces to 1". The sleeve would have to match the diameter of the pipe. The second problem is to keep the pipe straight. That will be a major challenge since PVC is a relatively flexible material. This projects is something that requires a lot of skill and knowledge of lamination. If you want to learn, start with a flat horizontal panel. What is the application of what you are building?
     
  3. VictorVictor
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    VictorVictor Novice fiberglass

    Reply to Gonzo

    Thanks Gonzo for your reply.

    I have already tried the sleeve and it does match what the company says in that the 2 inch sleeve is compressible to 1 inch. I have already confirmed that. At the 2 inch end the sleeve fits perfectly. These two concerns are not concerns.
    Secondly, I have already split the ends of the telescoping sections and inserted one into the other. This is a done deal and the entire length is perfectly straight and secured with stainless steel hose pipe clamps. This is not a concern either.
    Which of the three methods do you see as the best one? Or is there still another way you would tackle the epoxying?
    Waiting for your reply.
    VictorVictor
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    What is the application, as typically you need to caramelize the PVC to get a good epoxy bond. I'll second what Gonzo said about keeping it straight. 4 saw horses, spaced 9' apart, isn't going to produce a straight length of 2" or 1" PVC pipe. It will sag with the weight of the epoxy saturated fabric. If this is a mast, it's way too skinny and if made stiff enough to support it's own weight, it'll be damnn heavy too. What is this for?
     
  5. VictorVictor
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    VictorVictor Novice fiberglass

    Hi PAR;

    Thank you too, for responding. Both yourself and Gonzo are concerned about things which I am not giving high priority to. I’ll explain why:

    I have already sandpapered with rough paper a 6 foot test piece of sched 40 pvc 1 1/2 inch dia pipe to determine if the 2 inch fiberglass sleeve I have and 60 minute epoxy resin will work. It does. I am satisfied that the bond I get will be adequate for my purpose. My 6 foot experiment is strong and well bonded. How to scale up to the full blown larger 35 foot telescoped pvc concatenation is the problem where I need your advice.

    The purpose of the 35 foot mast is to allow me to place a 35 foot long copper wire alongside the pvc strengthened mast for a vertical radio antenna which need not be perfectly straight nor even pretty. There is no option to use any other length of wire or pipe different than 35 feet. That is a strict requirement.

    I only need to know if in your collective opinions applying epoxy to only part of the fiberglass and later applying more resin to the remaining (un-epoxyed) fiberglass to eventually make a fully enclosed seal of fiberglass encapsulating the entire mast will preserve the strength I would get if I could epoxy in a single application, or whether doing the epoxying in two or more steps will result in a weaker result. The question is, how to achieve the full length mast while preserving as much of the maximum strength as possible, considering that the full length cannot be epoxyed in a single step.

    Eventually I will place the 35 foot vertical mast/antenna on my boat. I will have a pulley at the top of the main mast which will pull into a vertical position the initially horizontal 35 foot pvc mast.

    Thanks very much for your advice.

    VV
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Victor, go looking for a stand of bamboo, must be plenty in Florida, where I live is a similar climate and there are some good samples to be found. You can join it easily enough with ferrules.
     
  7. VictorVictor
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    VictorVictor Novice fiberglass

    Mr. Efficiency:
    Thanks for the suggestion about bamboo. Yes there is plenty in Florida. Can you help me with the questions I listed for the pvc that I have?
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    The advice you've been given would be apt, it would be a very tricky exercise. Trying to glass around sudden discontinuities with woven material is a nightmare. I think you'd be better to use fibreglass tube, you could join sections, going down in diameter, even top it with a long fishing rod blank. But that old Rangoon cane appeals ! I'm told fishing rods up to 16 feet long made from it, were used in the old days.
     
  9. PAR
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    PAR Yacht Designer/Builder

    He could protect the saw horses and 'glass the whole thing in one continuous shot, lifting the pipe at the saw horses, when it's time to do under them. The problem we see that you don't is, the relative strength and modulus of the sheathing, without knowing the loads. This sheathing obviously isn't necessary for waterproofing, as the PVC is alone. In other words, what is this 'glass sheathing intended to provide?
     
  10. VictorVictor
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    VictorVictor Novice fiberglass

    Ok Mr. Efficiency:
    I think I've got a consensus opinion that what I want to do is not going to work. I appreciate all the advice I have been given. Guess I'll come up with another way to build a vertical radio antenna for my boat. Thanks to all.
    VV
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    Sounds to me you'd be better to have your copper aerial inside something flexible and hollow, like garden hose, but with good tensile strength, so you can tension it down at the base of your boat mast, so it doesn't flap around too much. Talk to a hose supplier, imo.
     
  12. VictorVictor
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    VictorVictor Novice fiberglass

    PAR Thanks.

    You have the main point in hand. Which is:
    Yes, I could epoxy the entire mast all at once. The problem with that is that in so doing the mast will be glued to the saw horses and that is what I want to avoid.

    The alternative ideas are most welcome. But the main question about whether a fiberglassed sched 40 pvc pipe can be strengthened sufficiently sith fiberglass to withstnand the stress when moved from horizontal to vertical is still going to be an experiment

    The mast lying horizontal will only need to be raised into a vertical position occasionally but must be strong enough to withstand the stress by being dragged at the top from horizontal to vertical.

    The main idea is, is there enough strengthening using 10 ounce fiberglass to withstand the bending moment from horizontal to vertical by dragging it upwards. While vertical there is almost nothing stressful. The vertical mast will be guyedat several levels for absolute safety and security. I want it to remain in place in 100 mph wind which I might encounter at sea for communications. (Which I hope I never experience.)

    I think I am going to epoxy the entire mast while supported on 4 sawhorses but omitting a band at the sawhorses. I'll go back later and epoxy those 4 bands and hope that the final outcome is strong enough to tolerate the move from horizontal to vertical. All this is an experiment anyway. I have long been wanting to use pvc pipe as a comparatively inexpensive way to raise a wire up nearly 40 feet without having to buy an aluminum mast which is way more expensive.

    Thanks for the suggestions and help.

    VV
     
  13. VictorVictor
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    VictorVictor Novice fiberglass

    Thanks Mr. Efficiency:
    I have radio antenna modeling software which gives specific radio design parameters as output. Enclosing a copper wire inside a hose of rubber or vinyl changes the impedance enough that it is no longer the best way to do it.

    I'll actually have a few lengths of wire tacked alongside but not in direct contact with the pvc pipe so as to preserve the radio efficiency . Each wire will add weight so putting every wire in a hose is unacceptable weight wise. No wire can touch any other wire.

    Additionally, I don't want to put the stress on the main mast of holding up the antenna at the same time as supporting the sails while underway. But thanks for the idea which never occurred to me.
    VV
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    If the worry is the thing busting as it is elevated, but will be fastened at regular intervals once up, some kind of hose or flexible tube would have been ideal, would it not ? I'd keep the epoxy for another day !
     

  15. SamSam
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    SamSam Senior Member

    You could run a cable up the center of the thing and stretch it tight with a come along (to take the place of sawhorses for support) and then fiberglass the whole tube at once. Or just fiberglass the joints, I can't see where glassing the whole length of the thing is required. Why can't you just haul up one end of the wire and stretch it tight...?
     
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