New Design Temporary Female Mold Build Help...

Discussion in 'Fiberglass and Composite Boat Building' started by bjdbowman, Feb 12, 2018 at 2:55 AM.

  1. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    I didn't go back and read it again, but people that want simple tooling on cats use symmetrical hulls, so no reversing anything. You make one bow mold and it works for all four pointy ends, then one hull mold section and make as many as you need to for the length of boat you desire. These molds will need to be a little more durable, but you can put a better finish on them and have less work to do later.

    Wax paper and plastic can be used as a release film, but doing it in a female mold is tough, and the surface on some shapes is poor at best.

    There are sprayable waxes, I used to use one that you heated up, when sprayed it would cool and become a little firmer.

    Hand waxing melamine coated plywood is about the easiest thing you will do in the entire project.

    There are spray, roll or brush on sealers that will give you a much better finish on plywood with no sanding, but they do need waxing.
     
    rxcomposite likes this.
  2. Rumars
    Joined: Mar 2013
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    Location: Germany

    Rumars Senior Member

    Well if that's your goal then just go buy an old cheap fiberglass boat. Some places they are even giving them away for free. Even if you have to repower or redo some of the interior you will be ahead of the game in terms of time and money.
    If you try to build you will only waste money and put yourself in danger.
     
    SamSam likes this.
  3. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    F8AB6060-9466-41AE-AD8C-338ADCE5D80A.jpeg 57E488B0-66BD-402D-91C8-89B9EEF253A2.jpeg 43F3CC5F-84F2-463D-8C36-9CDA67294657.jpeg C4D682BC-AD90-4EC9-9E49-52665DCA1E94.jpeg 53A4C314-B574-4CA4-842C-F6FB081A269C.jpeg Here is a female jig in various stages and a vac table. The hull is lifted with a gantry as there are no pick points or places for humans and the size at 32’ is too heavy for safe man lift. This space is 24’ wide by 36’ long for 32’ cat. Only one hull at a time can be built with this space and method. The first hull is outside under cover. In order to facilitate this build; it takes several people to vac bag a large panel and two people to move them into the jig. You could use other methods, but the cost of one of the four main hull panels (8 needed) is about $600 for core and about $400 for glass and epoxy and consumables and &400 labor.

    You would be better off building in plywood if you want a cheaper boat that is easy to build. With plywood; you can build the boat and handglass it. The method I am using is 3000 man hours.

    Start with budgeting time, money, and space.
     
    rxcomposite likes this.
  4. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    I tend to agree, if time, effort and money are a concern, buying a used boat is cheaper, faster, and most likely safer.
     
    fallguy likes this.

  5. rob denney
    Joined: Feb 2005
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    Location: Australia

    rob denney Senior Member

    Wax paper over the mould will work well as a release, although some Australian wax paper doesn't work so try it first. Any tears or missed overlaps and you have a stick up. Brown packaging tape also works, but after one application, tends to fall off. We use thin plastic (about the same thickness as Cling Film, but without the clininess) drop sheet material as it comes in 6m x 4m sheets and has a bit of give.

    Gel coating any of these is a waste of time and material. The gel coat will need sanding and polishing to look presentable and all the joins will require gel repairs. Put a layer of peel ply wherever you want to paint or secondary bond, it is much easier than sanding. Use house paint.

    What you are planning is easier, rougher, heavier, dearer and maybe quicker than conventional bucket and brush building, but will be slower and use more materials than Intelligent Infusion INTELLIGENT INFUSION – Harryproa http://harryproa.com/?p=1845 which is a development of the build method of the hull in the video above. Making 3 moulds then reversing them and hand laminating 6 panels then joining them and filling and fairing the result is crazy when you could build a mould and infuse 2 x half the hull and deck, then simply glue in all the exact fitting bulkeads and glue the 2 halves together, with all glue joins being self aligning. No edge treatment, no grinding or cutting cured laminates and no wet laminating. Half a hull for a 36' cat will be liftable by 4 people. or solo if you have reasonable roof beams or can make a scaffold.

    Maybe build a small piece of your boat (or just list the stages and give each a time, mess, waste, toxicity and hard work rating), then consider which is the best way to proceed.

    Bolting sections of hulls together is a good idea, we use it for removable bows. For major sections of hulls, especially those with shroud, forestay and traveller loads, the reinforcing around the bolt holes should be massive and far reaching. Doorways, etc in the bulkheads should be well above the waterline as you will be lucky to make it reliably watertight. Multiple bolts will help keep it aligned. The work involved in all this will make you wish you hadn't.
     
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