mold building specs

Discussion in 'Fiberglass and Composite Boat Building' started by brokensheer, Mar 23, 2018.

  1. brokensheer
    Joined: Jun 2009
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    Location: So. Md

    brokensheer Senior Member

    Hi Folks I have a plug built for an 18' x 6' -6" outboard powered skiff,, My question is in using 2oz csm and 24 to 25 oz fabric who many layers would be suggested,, this mold will also have wood girths and longitudinals over foam pads for straighten,, Thanks in advance
     
  2. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Unless you plan to use a core you wouldn't normally use any glass other than CSM for the mold. CSM may leave some print on the surface of the mold, but woven or stitched fabrics can cause a great deal of print through that may return no matter how many times you sand it to remove the surface distortion. Fabrics can be used behind a core if desired.

    The mold would probably be around 3/8" thick with a frame held off the surface a few of inches and glassed in place.

    The type of resin used can influence surface profile, speed and method of building it too, you could build it in one day with some resins, or a week with others.

    For an even better surface profile you can use one or two layers of veil against the gel coat, plus a barrier coat.
     
  3. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    I find it interesting you would build a mold for a nearly 19 foot boat without having a lamination schedule and a resin specified or at least recommended.

    Care to expound a bit?
     
  4. brokensheer
    Joined: Jun 2009
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    Location: So. Md

    brokensheer Senior Member

    Thanks for the reply Ondarvr, I follow you I have planed to use a 2- 3 mm core mat as well

    Fallguy, I have a schedule for the hull, just have not built a mold in about 5 years,, just reaching out to see what others are doing, thanks for the input !
     
  5. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    What resin are you going to use?

    I'm kind of an AOC MoldTru fan right now, easy to use, low shrink and strong.
     
  6. KD8NPB
    Joined: Mar 2018
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    Location: South Carolina

    KD8NPB Junior Member

    AME 6001 skin/barrier + Optiplus 8094 bulking.

    Not sure if I like the Optiplus or not.
     
  7. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Optiplus is much more difficult use, it's very thickness and temperature sensitive, the MoldTru is much more forgiving and works in the same way.
     
  8. brokensheer
    Joined: Jun 2009
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    Location: So. Md

    brokensheer Senior Member

    for this job its just general Poly Laminating resin
     

  9. ondarvr
    Joined: Dec 2005
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    Likes: 123, Points: 63, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    For this purpose a DCPD blend GP resin would work best, a straight ORTHO or ISO would shrink and move more while building the mold and when you put it in use.

    How long do you plan to use the mold and what type of finish do want on the hull.
     
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