Question on vacuum bagging and pleats

Discussion in 'Fiberglass and Composite Boat Building' started by ahender, Oct 21, 2020.

  1. ahender
    Joined: Jan 2009
    Posts: 89
    Likes: 3, Points: 8, Legacy Rep: 10
    Location: Athens, GA USA

    ahender Junior Member

    I am fixing to infuse my 12' canoe mold. Yes, this has been "going to infuse my 12' canoe mold" for quite some time now. It has been recommended I cut my bag about 50% larger than the interior mold dimensions. It has also been recommended that I start pleats at one end. One online video recommends to start in the middle. I think I will start my pleats in the middle. After I push the bag into the mold to guarantee there will be no bridging, how much bag overlap on my flange/tape seam should I start with?

    I have included an image of the mold, after I have stripped off one unsuccessful attempt to attach a bag.

    Thanks.

    Alan

    mold.jpg
     
  2. wet feet
    Joined: Nov 2004
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    Location: East Anglia,England

    wet feet Senior Member

    I'd go at least couple of feet longer than the mould and a couple of feet wider.Looking at the comparative fullness at the ends,that is a clue that some tucks will need to be in the region.I would locate the ends of the bag centrally and then move to the middle portion to get a section attached there with equal amounts of slack left at each end.I'd start again in the centre of the unattached bag and work to the adjacent sections with tucks located where there is enough slack to sensibly include them.Its much better to have an ample sized bag than to have to worry about whether it will reach all the parts it should reach.Have you decided where the resin feeds and vacuum line will be located?
     
  3. ahender
    Joined: Jan 2009
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    Location: Athens, GA USA

    ahender Junior Member

    Thank you. The resin line runs along the bottom and the vacuum line runs around the flange. The reinforcement stops about five inches from where the flange starts.
     
  4. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    I think, after careful thought, you will want to apply tape to the flanges. Then remove the paper from one side and secure the bag with a 6" to a foot overlap or so.

    Then, to avoid bridging in the ends; lotsa pleats. On each end.

    Then work your way to middle other side. The extra bag for the ends will mean extra bag in the middle.

    End at the middle opposite side.

    I have lots of bag experience. I never worry about a wee bit of bridging for wet bagging, but you need to for infusion. Never did a canoe, though.
     

  5. ahender
    Joined: Jan 2009
    Posts: 89
    Likes: 3, Points: 8, Legacy Rep: 10
    Location: Athens, GA USA

    ahender Junior Member

    Thank your for your replies fallguy.
     
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