DIY Simple Catamaran Sailboat Design

Discussion in 'Boat Design' started by WilliamPrince, Oct 10, 2013.

  1. scotdomergue
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    scotdomergue Scot

    I don't think I understand. What makes you think it is short? Relative to what? The total length will be 1 cm shorter if you push them together. But if they measure correctly, then that would seem to be the proper length of the full length panel. No?
     
  2. WilliamPrince
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    WilliamPrince Junior Member

    The entire piece is made of 3 pieces; two ends and a middle. Both the ends and the middle have "checksum" dimensions labeled in the plans, of one corner to the opposite, and all pieces are supposedly accurate. However, when I lay them out as in the picture, the problem is apparent. For the total length of the panel to be accurate, I have to spread the panels with a small gap in the middle, and if I push the panels together in the middle, my total length is incorrect.

    I either have to make entirely new mid panels to elongate them 1 cm, fiberglass and epoxy over the gap in the middle panels, or put them together normally and have an overall length 1cm shorter than the plans call for.

    Well, I am starting to fiberglass splice my other panels, it is going well. I hope to be done by today.
     

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    Last edited: Oct 31, 2013
  3. scotdomergue
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    scotdomergue Scot

    My initial thought was that you might have one piece "upside-down" relative to the other two (I did that with one on the Marsh Duck and had to sand the fiberglass off and flip it - see PDF). But the picture shows enough curve to the full length panel that I would think this would be obvious.

    It's possible that there is an error with the plans, or there may be something about how you're putting it together that's off, and this is an opportunity to understand and correct while that's still easy to do. Or maybe there's just something about how you're doing the measurements.

    Try to envision exactly how it will ultimately go together with the other full length panels (creating curved sides, rocker, flare &/or tumble-home, etc.). You might measure the full, curved length of the edges of the middle and top panels that will be stitched and glued together and see if those are the same or very close to it . . .

    If you can't figure out how and why it seems "off", I'd probably go ahead and push them together tight and then do whatever seems necessary to make it work when you stitch it all together. I can imagine adding a small, shaped piece of solid wood on one or both ends to fill in a slight gap on one or both ends at that stage.

    But I'd feel better about the whole thing if you can figure out why the measurements aren't consistent at this point . . .
     
  4. scotdomergue
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    scotdomergue Scot

    Looking at the picture: the straight line pictured is shorter than the length of the curve . . . And neither will correspond to the length of the boat. Do the plans tell you to measure the full length panel? And explain exactly how to do that? And define what the measurement should be?
     
  5. El_Guero

    El_Guero Previous Member

    OK, sift the flour, a coffee grinder (or blender) should be able to make the rest into flour. Just don't run it so long it burns on you.

    The epoxy 'is stronger' than the surrounding wood. But, I don't like the gap, can you tape that afterward? Or place a strip of ply over it on one side? 6 inch overlap of the joint?

    Wayne
     
  6. WilliamPrince
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    WilliamPrince Junior Member

    I think I will push it together as you say; to shorten the ends of the other pieces to make up for it, if I have to, would not be so hard.

    So, I attempted to put fiberglass on the other, more well-fitting panels. In retrospect, I should have mixed a practice batch of epoxy first, and played around with it, but in reality I just went for it. And it was somewhat of a fiasco.

    First I mixed the epoxy, 6ozs, which was way too much for my job. I began to soak the wood, like in the pygmy video. Not sure what drove that decision, I just maybe thought it would make a stronger bond. I laid the fiberglass on top, squeegeed out the excess, spreading it to the sides of the wood. I guess the fiberglass was transparent.. As close as I felt it would get. So I put another plastic shoppig bag on top of the whole thing, and put a big barrel of water on top for a weight. Did the same with the second one.

    I had a bunch of epoxy left, so I had the brilliant idea to spread it all over the wood. I did so, and tossed the extra. Now the epoxy all over the wood is forming bubbles, and who knows what the hell is going on under those weights and shopping bags.

    A very sloppy job, I think there will need to be some extra work done to fix this ridiculousness.

    P.S. i am an idiot. Epoxy is currently curing on my hands, feet, shoes, and drips all over the floor and table
     
  7. scotdomergue
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    scotdomergue Scot

    No, not an idiot, just learning through experience. With any luck at all, it will be fine under the weights . . . you'll probably just have to do some extra sanding . . . and next time you'll mix less epoxy, be more skilled at the whole process, and it will go better and better . . . until the next bit that is different from anything you've done before and you'll have another opportunity to learn . . . have fun! }:cool:
     
  8. WilliamPrince
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    WilliamPrince Junior Member

    Yes you are right, but I do feel downright stupid sometimes. Thanks everybody for the help, Scot I can't thank you enough for that pdf, it is very very informative. I will probably not finish these panels today, but hopefully tomorrow.

    Will update the thread with general progress, or message you guys directly if I have a more specific inquiry.

    Thanks for sticking with me guys, its coming together... :)
     
  9. El_Guero

    El_Guero Previous Member

    William,

    Get disposable GLOVES. Or, even leather gloves and use them till done.

    Do this in a well ventilated area. just under 1% of people exposed to epoxy develop SEVER ALLERGIES .... Much better safe than sorry.

    Epoxy is a learning experience, you now know that those that told you in videos to practice first, and not mix more than you needed, were correct.

    Learn from them .... you are taking on a huge endeavor. Not the biggest ever taken on, but huge.

    I am not sure about the bubbles, really not, some of them should absorb into the wood. But weren't you able to squeegee out bubbles as you laid the epoxy?

    wayne
     
  10. WilliamPrince
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    WilliamPrince Junior Member

    Wayne, there are no bubbles under the fiberglass, only forming in the epoxy I spread over the wood. I just went and scraped them all off, but I don't think it did much good. I think I handled the epoxy too much or something and introduced a bunch of air to it... Luckily, I think the stuff under and in the fiberglass is okay, just what I put on the wood is affected.
     
  11. El_Guero

    El_Guero Previous Member

    PS - IF YOU HAVE EXCESS EPOXY ON YOUR WOOD, it is better to wipe it off with an old rag.

    You can sand later, but the less sanding the better - epoxy is harder than the wood, so it is easier to sand the wood than the epoxy ....

    Clean up your skin with gojo, or other shop cleaner. Do not wash your hands with vinegar - clean tools with vinegar. Vinegar makes your body absorb more epoxy .... gojo won't.
     
  12. scotdomergue
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    scotdomergue Scot

    If I remember correctly wood will off-gas a little as it warms and that can form small bubbles in epoxy. This is addressed in the West System User Manual. You can avoid the problem by doing any epoxy over bare wood at the time of or after maximum temperature . . . Going by memory here as I'm not home so can't check my West System Manual.
     
  13. El_Guero

    El_Guero Previous Member

    That's right .....

    You want the wood to be warmer and wetter than surroundings! Or, is that warmer and drier? I have read conflicting on the wet.

    I forgot what West recommended.

    Then it absorbs the epoxy into the grain .... rather than off gas .... I should never forget about off gassing.
     
  14. WilliamPrince
    Joined: Oct 2013
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    WilliamPrince Junior Member

    Okay, somehow against all odds the fiberglass splice I did proved to be a success... Structurally at least. I will continue the process today on the other ones, again I am very limited by flat area to work with, I only have 2 plastic foldable tables really to build on. Anyways, one of the joints came out looking like this, the ridgesa are very hard... I think they are cured epoxy. Well nothing that wont come off with a bit of sanding eh?

    Im a little behind in my schedule, but that was kind of an arbitrary time frame, and as Skyak pointed out, some things will go faster than I planned for, so we will see.

    P.S. If I measure out epoxy with plastic measuring spoons (teaspoon tablespoon type things), and quickly immerse the spoons in water after use, will that prevent any cure on the spoons?
     

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  15. Petros
    Joined: Oct 2007
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    Petros Senior Member

    water will have no effect on the curing of epoxy. You might clean the spoons with acetone. Or find some cheap disposable way to measure, like a paper cup, and just throw it away with each batch.
     
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