Fiberglass River Kayak build - high level process

Discussion in 'Fiberglass and Composite Boat Building' started by Strapheap, Jul 15, 2018.

  1. Strapheap
    Joined: Jul 2018
    Posts: 2
    Likes: 0, Points: 1
    Location: Missouri

    Strapheap New Member

    I've paddled a 13 foot recreational Necky kayak on rivers and lakes in the Midwest and i'm now looking to build a higher performance kayak for trips down the lower Missouri - the long distance MR 340 race is one of my goals.

    Based on web research my high level understanding is as follows, I'm early on this path and feedback will help steer me in the right direction:

    I first need to employ kayak design software (Kayak foundry or Bear Boat) to create a blueprint. I weigh 165 lbs and stand 5' 6" tall, and am anticipating something appx 16 ft by 22 inches. The design would incorporate two bulkheads, one in front and one behind the cockpit. Using specs from the design software I'll use foam to create lateral cross sections of the hull, then connect the foam crossections with foam or wood strips. Then, cover with several layers of heavy duty cling wrap. This will serve as the foundation of a fiberglass plug. Once wrapped, I'll coat the plug using plaster or something similar that can be further shaped... and eventually coated in gelcoat or a similar coating that will allow resined fiberglass to release.

    At this point I can use the plug as a male mold, or create female molds using fiberglass. Going the route of using a female mold would provide the benefit of a smoother exterior in the finished kayak. Two pieces need to be created, one for the hull, one for the deck.

    With a mold coated in a surface that will allow for release, paint a layer of gel coat, wait for this to dry. Next, cover in 7.5 oz fiberglass fabric and use rollers and squeegees to saturate with polyester resin, acting quickly to apply the resin and remove air pockets. Next, cover in 1.5 oz chopped strand mat and saturate with resin. Next, another layer of 7.5 oz fabric and polyester resin.

    Repeat process using the other mold. Then, apply a suitable adhesive to join deck and hull pieces. Once the adhesive is set, cover the joint with a strip of fiberglass/resin. Next, create bulkheads and join the bulkheads to the interior surfaces using a similar adhesive+fiberglass method.

    Any feedback or corrections to this basic understanding is really appreciated.
     
    Last edited: Jul 15, 2018
  2. Blueknarr
    Joined: Aug 2017
    Posts: 706
    Likes: 115, Points: 43
    Location: Colorado

    Blueknarr Senior Member

    Welcome

    Short answer and almost short explanation.

    I'm not in a position to speak on the design portion of your plan.

    The plan, as you have outlined, is conducive to making several copies of heavy (mediocre performing) kayaks. You mentioned a solid glass lay up primarily using Chopped Strand Mat. CSM is bulky, very HEAVY and relitively weak. Almost exactly the opposite of what a performance craft needs. Carbon fiber is incredibly light and strong. The amount you will need won't break the bank

    There are ways of building one off boats that don't involve the tedious expense of building plugs or moulds. Moulding makes the first copy extremely expensive and the tenth affordable. My impression is that the very lightest kayaks are non-moulded skin on frame. Stitch and tape construction utilizing carbon/foam/carbon should yeald a competitive float.
     
  3. ondarvr
    Joined: Dec 2005
    Posts: 2,033
    Likes: 153, Points: 63, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    The lightest would be single skin carbon and epoxy infused, these aren't that durable though, it needs to be beefed up a bit to survive, so the weight goes up a bit.

    What you described will work, but may not be the easiest or cheapest way to do it. Are you looking for an interesting project, or a way to get a Kayak for a lower price.
     
  4. Strapheap
    Joined: Jul 2018
    Posts: 2
    Likes: 0, Points: 1
    Location: Missouri

    Strapheap New Member

    I'm looking to get a higher performing kayak for a lower price. The goal is to obtain a kayak similar to the '18x' model by Epic, while making cost-cutting adjustments. For example, from what I can tell, carbon fabric costs 6 times as much as fiberglass fabric. I was planning to use fiberglass for cost savings, and as a compromise, in the interest of keeping weight down in the finished kayak, reduce the hull length by 2 feet. At my bodyweight, based on notes found on the internet anyway, a 16 ft hull will still yield a higher performance river kayak.
     

  5. ondarvr
    Joined: Dec 2005
    Posts: 2,033
    Likes: 153, Points: 63, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    It will be cheaper, easier and quicker to buy a kayak that's built like you want it than to make one.

    Changing from carbon and epoxy to polyester and glass, then making it 2' shorter will make it a very different boat.
     
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