extreme light plywood Kayak ????

Discussion in 'Boat and Accessory Building' started by Roy222, May 25, 2018.

  1. Roy222

    Roy222 Paddler

    Joined:
    Jun 2, 2009
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    Have any builders out there built a super light stitch and glue Kayak?
    I am thinking :
    4 mm thick plywood - 6 or 4 panel design
    Fiberglass only the bottom & inside where you sit with 4 oz. glass
    Fiberglass the seal ring around the cockpit opening
    Seal the seams with thickened epoxy and glass the outside of the seams with bias cut 4 oz. glass
    Use paint to seal the rest of the boat
    Use a foam seat
    Maybe foam bulkheads or that hollow core plastic used to make lawn signs — even folding kayaks
    Over lapped hatches sealed with foam — no extra seal ring in hull


    The boat would only be used for flat water and near shore

    Is 20 pounds possible with a 16 foot long boat?

    Roy
     
  2. mick_allen

    mick_allen Paddler & Moderator

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    I think Mac50L does something similar, but maybe with 3mm ply. Look back at some of his old posts and read the approach he uses. I believe he gets down to about 35 lbs or so.

    The basic thinking is seductive: plywood is a laminate, so other than protecting it from water, why put other laminates [fibreglass] on the surface - so just adhere the edges and seal the surface.

    The downside will be constant upkeep to assure that any bare wood gets sealed. I would imagine that there would be noticable spot discoloration if unpainted wood was used, but it would depend on the upkeep.

    20 lbs sounds too difficult, check the bare wt of the ply used and that would give initial idea without any glue or seal coat. Using the 16-2 shearwater as a S&G example the overall ply area would be about 48 sq ft.
     
    Last edited: May 29, 2018
  3. Mac50L

    Mac50L Paddler

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    I thought you wanted light? Use 3mm, single chine or no chine and tortured ply. One piece curved-over deck, without deckbeams.
    Why? That's adding a lot of weight.
    Now you're talking light. How about my latest one, 13 kg into the water for testing? My last 2 were 18 kg fully equipped, rudders, hatch covers, rudder pedals etc. Yes, could knock a kg or so off that if needed.
    Just day paddling?
    10 kg - possibly though the epoxy would need to be minimal and one coat of paint.
     
  4. woodman

    woodman Paddler

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    Bates City Mo.