55 Fisherman moulds

Discussion in 'Boat Design' started by fede, Jan 3, 2009.

  1. fede
    Joined: Sep 2003
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    fede Senior Member

    Hi everyone,I'm trying to figure out the best way to divide (break down) deck and superstructure (cabin) molds for a 55 ft fisherman.
    The boat has a Fly and it is possible to have a single mold for the deck and superstructure (cabin) ,including the fly since all the draft agles are positive except for the part under the fly (where the door is located )
    As I see from theire websites, both Viking and Bertram make Deck and Cabin in a single piece.
    The thing is that I would like not to have to glue and screw the superstructure to the lower part of the cabin,this way though, I will not be able to include the interior of the cabin in the deck mould,the interior could be done with what I call in Italian a "countermoulded piece" that have to be attatched to the inside of the single piece deck + cabin, or the interior could be done in wood,since all the interiors wil lbe done like this.

    So the 2 solutions are :
    1 mould for deck and cabin and interior of the cabin up to the area just below the glasses and then another mould for top of cabin and fly.
    OR
    1 mould for the whole cabin and fly and hand made interiors or "countermould" for the interior.

    It's difficult to explain since english is not my lenguage,hope I have been clear,I may post some more screenshots to make it clearer...attatched is one picture
    If anyone has some pictures of something similar (building pics) it would be helpful.
    Thanks in advance,
    Federico
     

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  2. robherc
    Joined: Dec 2008
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    robherc Designer/Hobbyist

    first, I would have to ask, what exactly is your construction method? Glass over heat formed foam/lap strips of foam? Or are you trying to cast a part (VERY different process from a mold-making standpoint)?
     
  3. fede
    Joined: Sep 2003
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    fede Senior Member

    Hi robherc,the construction method is a traditional one, fiberglass from female molds.
    We are in the process of making the hull plug now.
    What does "cast a part" means ?
     
  4. robherc
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    robherc Designer/Hobbyist

    by "cast a part" I was (probably out of ignorance, mind you) trying to make sure you weren't trying to cast a foam core out of pourable foam, or something (i.e. similar to a cast iron pot that is made by pouring melted iron into a sand mold).

    It would seem to me (though I have VERY little experience here) that you could use a male mold to form the superstructure & interior, and still form them all as one piece with the deck. It would probably be quite difficult in reality, but it seems workable in my imagination.

    Also, if you are making the "hull plug" does that not mean that you are using male molds already? (i.e. goes inside the part makes mold male, outside the part makes mold female)

    Sorry if I make myself ignorant with this post, but I am trying to offer help while still VERY new to designing boats.
     
  5. robherc
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    robherc Designer/Hobbyist

    on second thought, any interiors that were directly below the deck (as opposed to directly below the fly) would not work with my method, so it may be useless to you...I don't know what your interior design is, so I don't know.
     
  6. fede
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    fede Senior Member

    Thanks,this is a production boat so everything will come out from a female mould.
    The male plug is built to obtain the moulds from them.
     
  7. robherc
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    robherc Designer/Hobbyist

    oh, ok...then I guess my idea wouldn't help much as you'd have to make a new male plug for the interiors for each piece...sorry...guess the only way then would be to sandwich 2 female mods together, with the deck portions already formed to them, and form the rest while physically standing inside the mold...probably not very practical, so I guess 2 pieces would be the better way to do it then.
     
  8. marshmat
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    marshmat Senior Member

    Hi Federico,

    My first thoughts would be that the technique for moulding the deckhouse will have to be reconciled with the structural function of the deck. The deck on a fibreglass boat generally has to handle a lot of the torsional stresses on the hull; the need to handle these loads will serve to limit the number of places where you could actually put a joint without having it work loose over time.

    I would be tempted to try moulding the deck, superstructure and flybridge as one piece, like most builders do. You'll have to figure out how the various loads are going to carry through this structure, and where to add extra bracing to keep it from flexing as the hull twists. I would think that if you try to put joints partway up the superstructure, they'll tend to work open as the boat flexes.
     
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  9. fede
    Joined: Sep 2003
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    fede Senior Member

    Hi Marshmat, yes this the way I will probably proceed.
    And the interiors will be done with wood (one off)
     
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