Can styrafoam logs and fiberglass get along?

Discussion in 'Boat Design' started by socrates, Aug 7, 2010.

  1. socrates
    Joined: Aug 2010
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    Location: Alaska

    socrates New Member

    I'm a newbie. To this forum and to boatbuilding. But, I ain't scurred. Gotta start somewhere, right?

    Here's the idea. I need to make some pontoons. I have some styrafoam float logs. I have a bunch of industrial shipping saran wrap type packing plastic. I'm thinking that I'll put a thin piece of plywood on the top of them to help with the rigidity of the logs, then I'll double or triple saran wrap the logs, fiberglass over it.

    Lots of questions about the process.
    1-Does this idea sound ridiculous?
    2- will saran wrap insulate the logs enough to not allow the resin to make contact with the styrafoam.
    3- I'm planning on putting a motor on the back of the platform I'm building and using it to go places now and again. How well will this sort of pontoon hold up if left in the water for extended periods of time?
    4- Will one layer be enough to give an acceptable level of protection to the foam, or would the strength of the fiberglass valuably increase if I were to put more layers on?

    Thanks in advance.
  2. messabout
    Joined: Jan 2006
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    messabout Senior Member

    1. Ridiculous No....Impractical...Yes

    2. Enough saran wrap, tightly seled might work OK. If you use epoxy, the saran wrap will not be necessary.

    3. If your glass job is good, the boat will last a reasonable length of time but the foam will eventually absorb some water. The boat will become progressively heavier with time in the water.

    4. No! One layer of glass is not nearly enough if you plan to use the boat for more than a mere float. The motor will demand that you have a decently rigid skin over the foam.

    5. Question you did not ask: Is this a good idea? NO! If you want to build a boat, them I/we encourage you to do so. But build a boat according to conventional methods, not with styrofoam and saran wrap.. It is almost a sure thing that you can build a simple skiff as quickly and as cheaply as the foam floaty thing. The skiff will be a real boat that has the benefit of proven ability, it will accept a motor of reasonable size, it will have some residual value that the foam thing does not, it will almost surely perform better in all kinds of water conditions.
  3. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

  4. mark775

    mark775 Guest

    But... if you don't want any more than an occasional move to somewhere in protected water, you said "now and again", I wouldn't coat the foam at all - just attach something stable to stand on and take the outboard. I don't want to see you cruising past in big water, now. This is for maybe getting across your cove on a nice day. The foam is stiff - you don't need plywood to stiffen it - just to control it. I have seen the same floating foam in successive years... it will last longer than what it is worth to try to make it into a real boat. If you want a real boat, you simply must follow the above advice.
  5. socrates
    Joined: Aug 2010
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    Location: Alaska

    socrates New Member

    Thank you guys. I got the general impression that if its stationary, as a dock, this might work. Any sort of movement, I ought to go with non-jerry-rigged, legitimate pontoons of the aluminum or plastic variety. I'm building a working platform that does need to move now and again- and not in a quiet cove- so the boat- though it would be much nicer for the movement, isn't practical for the application I need.

    Very much appreciated. I'll have to go back to the drawing board- but at least I didn't spend my time playing glue and paste like a grown-up kindergartner making something I ain't gonna be happy with.

  6. Ike
    Joined: Apr 2006
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    Location: Washington

    Ike Senior Member

    By the way use epoxy resin for the fiberglass, not polyester resin. The polyester willdissolve the styrofoam. Epoxy won't. Yes it is more expensive. Last but not least, I agree with the above, if want a boat, build a boat. If you want a float, the styrofoam blocks are fine.
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