Want to build some cabinets for the Helm Seats

Discussion in 'Fiberglass and Composite Boat Building' started by GPappy, Jun 9, 2012.

  1. GPappy
    Joined: Jun 2012
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    Location: Michigan

    GPappy New Member

    I have an older Grady White and one of the things that I really don't like about it is the Helm Seating. I have a pedestal on the captains side and a poorly made bench seat on the opposite side.

    I would like to construct some some cabinets to mount the seats on that I can build storage into. I have worked with fiberglass in moldless composites before but have never made a mold to build a part.

    Would it be best to learn the skills involved to make a mold and build some cabinets with a nice gel coat surface or would I be better off building some moldless parts with an painted epoxy surface. Any good sources for instructions?

    Thanks for your thoughts.

    Greg
     
  2. rawleyjerel@yah
    Joined: Apr 2012
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    rawleyjerel@yah Junior Member

    thats a matter of preference! it would be alot cheaper to get some marine plywood build your cabinets out of it using stainless screws and then cover it with some matt (two layers of 1 1/2 ounce matt) remenber to reinforce the points where you want to mount your pedistal seats to as in double up the plywood at these points then you can gelcaot inside and out. thats a cheaper fix, it would cost alot more to make a mold but if u do i suggest using malimean but do not wax the malimean as it will prerelease only wax the edges of it were the wood is exposed
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Using a mold to get your helm seats is a huge waste of materials and effort. A mold is only useful if you intend to pop several helm seats out of it.

    There are many methods you could employ: traditional "stick built" wooden, plywood over frame, taped seam plywood, cored composite, single skin GRP, plus many others.

    If you plan on using polyester or vinylester resin, then skip the wooden elements, except for trim and go with a one off method, better suited to these materials, such as foam core or single skin, etc.

    You don't need to use a resin system at all and could just make plywood boxes, using 1x2's in the corners and coated with you choice of paint or varnish.

    Ultimately, you'll have to pick a method, then you can work up a design suited for it. I've built dozens of helm seats over the years and plywood is easy, fast, most have the tools to cut it and with some inventiveness, can be very good looking.
     
  4. rawleyjerel@yah
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    rawleyjerel@yah Junior Member

    agreed but dont just tape the seems cover the whole box or youll end up with trouble down the line.
     
  5. PAR
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    PAR Yacht Designer/Builder

    Taped seams work just fine. The helm seats will not be immersed and you will not have any issues.
     
  6. SamSam
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    SamSam Senior Member

    [​IMG]

    [​IMG]

    Making a boxy female one off mold isn't very hard. This stuff (Home Depot or Lowes - the picture shows a 4 x 8 sheet being used as an erasable felt marker "chalkboard" ) is a little flimsy (3/16" masonite) but a cheap piece of foam or cardboard glued to the back stiffens it up (if needed). It's smooth and has a sprayed on coating that only needs to be waxed in preparation for molding. I've never tried it with epoxy, but polyester has never stuck to it. You have to radius the corners, I've used Bondo and modeling clay. There are plastic strips available for joining then, including a small radius inside corner, that might work, but would take a little touching up on the finished corners possibly.

    Depending on how handy/crafty you are, PVC pipe split into quarters can be used in corners. I've used 2" cellophane tape, such as for taping boxes, in molds. That foil tape used in taping heat and air ducts works real well also.
     
  7. PAR
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    PAR Yacht Designer/Builder

    Again, a mold for a one off project is like building it twice.
     
  8. GPappy
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    GPappy New Member

    Thanks all for the replies.

    The aircraft work I had been involved with used a foam core that could be shaped into complex shapes that were covered with multiple layers of cloth of different biases to add strength. Plywood is bonded in for attachment points. They use an epoxy slurry made with micro balloons to create a surface that can be sanded smooth.

    I agree that the plywood box would be very strong but I really like the looks of the gel coated cabinets that I see on the better boats and want something that looks nice. Lighter weight too. Since the consensus seems to be that a mold would not be worthwhile I will probably pursue the mold less composite.

    Thanks all.
    Greg
     

  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Just use foam. Cut to shape, wonderful radiuses and all, sheath with biax initially, for stiffness, then over coat with finishing cloth so fairing isn't so painful. The smooth finishes are the last portion of the build and will take the most time. Maybe toss some plywood or solid wood in there to lower the laminate requirements. A 1/4" plywood box would be more then strong enough if filleted and taped properly to hold a full size person, while still being quite light. It would rival any foam cored structure that was similarly stiff and strong, in the sizes I envision for a helm seat. In fact, you could add some foam (on the plywood box) to put the sweet radiuses in, covering all in finishing cloth and have the best of both worlds; light, big curves and strong.
     
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