first build 5m proa

Discussion in 'Boat Design' started by water sign, May 17, 2012.

  1. water sign
    Joined: May 2012
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: australia

    water sign New Member

    Hello everyone,

    I have found this site very interesting and since I am new to the community it is best to jump in head long without fear. I have designed a small proa and rig system similar to a junk, built a 2 part mold now ready to lay up. I work with epoxy and 10mm pp honeycomb core with a bit of hardwood. I am not qualified but have some experience. I have done a few test patches to get familiar with bagging and trial different lay up schedules etc...
    So far outer layer 200 gsm csm,
    2nd 660 gsm 0/90,
    10 mm pp core,
    3rd 440 gsm 45/45
    ???inner layer 200 gsm???
    somewhere a strip of uni glass/carbon 12in wide wrapping end to end the top of the hull overlapping the flat 50mm rail.The deep vee hull is straight and narrow with almost no curves or rocker except the ends. Both hulls are the same. length 5m beam .38m height .55m
    Before I do any real building the rc model will have to prove my design worthy as i am putting lifting foils or 'C' foil on the sail hull and a 'C' or 45 degree bruce foil on the lee hull. The rc model is deciding this for me of course. Tests are looking good so far. Trial and error learn as you go has been my life so to speak.
    Now I have learned too much and studied other peoples methods and designs to the point where I am afraid to do anything because of the conflicting opinions on so many engineering issues have overwhelmed me.
    method 1
    What Im thinking to do now is lay the stringer and core in the mold and vacuum the inner layers to it.Vacuum will pull excess resin away from the core and give a good bond to inner layer glass. Then pull it out putty up the gaps and glass over the lot like the male mold process. Since my molds are not faired being left with a peel ply texture on the outside is fine for me to flocoat i think.
    method 2
    The opposite. Lay outer layer of glass in the mold then core and vacuum it down.once cured Putty gaps etc.. and then lay inner layers of glass pre wet out vacuumed down. My fear is getting resin in the honeycomb with this method.
    1.Will any of this work?:confused:
    2.Will my shape be distorted when i pullit from the mold with only the inner or outer layer bonded to the core?:confused:
    3.Can I do both layers at once if i pre wet the glass on a table then vacuum the lot?:confused:
    4.Will there be problems in reinforcing the hull interior for daggerboard slots, crossbeam attachments, mast support?:confused: 5-6kgs a sqm too much or too little for end result?:confused:
    6. Am I totally off the mark?:confused:
    Thanks to all who may be interested i will be happy to hear any replies or answer any questions. I wont be doing much till this model really proves itself because what I have learned is that my hull design is a one of a kind which scares me because im sure someone has tried this before and failed. Where the boat is the keel and it never tacks only shunts has been proved gives me some comfort.
  2. rwatson
    Joined: Aug 2007
    Posts: 5,866
    Likes: 299, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    First - the model performance of scale model boats is not as significant as you may like.

    Interesting discussion including "I have no objection to whatever any modeler wants to do with his boat or his clock. It's a hobby, and you are free to pursue it anyway you please. My only objection is when someone tries to take towtank procedures and prove that they are somehow "real" and should be followed by all "right-thinking" modelers :) Tow tank procedures were designed to deal with a specific problem, and that problem is only real to the towtank. btw, towtanks are not held in the high regard they were held 100 years ago ... "


    Second - the kind of questions you are asking about construction can only be answered by qualified engineers, working on a proper design, and you will soon be getting all kinds of comments along those lines.

    You have a long design process to go through for a "non-standard" design like this, before you can get any sensible advice.
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