First time canoe build...

Discussion in 'Fiberglass and Composite Boat Building' started by lyda, Oct 10, 2016.

  1. lyda
    Joined: Oct 2016
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    Location: Galway, Ireland

    lyda New Member

    When I was a kid I remember by dad building a canoe (possibly from a kit) and it was fun to take out on the water. I have a fair chunk of free time these days so thought it might be an interesting project.

    I bought a used copy of "Building your own Kevlar Canoe" and have read it through a few times. I'm left with a number of questions and thought I'd ask people with some more experience.

    As a first timer I was wondering if it might be smarter to first go with just fiberglass as it might be cheaper to make mistakes with. Or should I just throw caution to the wind and try for kevlar to start? Is kevlar harder to work with than S-glass?

    I live in Ireland where plaster is still widely used. Would that be an ok alternative to the drywall compound mentioned in the book - the layer over the foam strips when making the plug?

    Lastly to prevent oil canning, the book suggests ribs made with foam strips, laminated into place with fiberglass. Would plywood ribs be better? Was foam just chosen because bending plywood isn't simple?
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    If you use 'glass instead of Kevlar, it'll be a lot heavier and defeat the reason for using Kevlar in the first place (weight and toughness). The same is true of plywood strips, instead of foam. It'll work, but will be much heavier.

    Working with Kevlar isn't much different than 'glass though it does look and feel different the first few times you do. With Kevlar, it's usually best to work inside a female mold, instead of over a plug (male mold). The reason is Kevlar is difficult to finish smoothly, without it being pressed into a mold, where it's surface can be controlled, particularly under pressure (bagging, infusion, etc.).

    To directly answer your questions, yes, you can use regular 'glass, but then you'll have a 40 pound canoe. Yes, you can use wooden ribs, but weight and rot potential are (again) issues. Basically the whole idea with a Kevlar canoe or kayak, is to keep it exceptionally light and really tough (rocks, stony beaches, etc.).
  3. lyda
    Joined: Oct 2016
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    lyda New Member

    OK. So the downsides are weight and rot.

    This would also be my first time to do much canoeing so I was planning on a tiny and very calm lake (Hackett Lough in Galway) which lacks rocks, etc. So strength isn't an initial concern.

    In addition for the build I was only planning to make a plug at first.

    The rot issue for the ribs is annoying. Obviously I'd try to seal it and dry it out, but one mistake and that would be an annoying thing to repair. So foam ribs sound better.

    The book I have punts on female molds, but from further reading and a number of youtube videos the process seems to be:

    1) Make a plug.
    2) Using 'glass make a female mold.

    For each canoe from that wax the mold, and build the canoe from the inside out. Then bag the whole lot and suck out all the air to the compress the layers.

    Have I got that right?

    So if I was to build a male plug, then build a practice canoe out of 'glass (saving the plug) I could later go back and semi-repeat the process to make a female mold and then build a kevlar canoe for further adventures (in Lough Corrib which is a much larger and more dynamic body of water). Would that seem like a rational plan?
  4. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    You can get away with using Plaster of Paris for fairing up a plug, though I recommend sealing it well. I've done a couple of times, but also used it for cold moulding.

    To make the female mould, you have to make the male plug. Then the female will be one piece or two halves, mabe a third part depending on the cockpit - if a Kayak not canoe. You can get reasonable quality with a hand layup, but better with vacuum bagging which will pull the air out.
  5. Petros
    Joined: Oct 2007
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    Petros Senior Member

    I do not see fiber glass as a problem, there are many production fiberglass canoes. cost is much less, and mistakes (which are almost certain to occur on a first time build) do not hurt as much.

    As PAR pointed out, the reason to use foam and kevlar is to save weight, you can acheive the same strength with fiberglass by using heavier fabric. I do not think the rot is as much an issue as PAR indicates, moisture intrusion into foam ribs is not desirable either. Either wood or foam has to be very carefully sealed or it will fill with moisture and get moldy either way. One other issues is that foam does not add any strength by itself, it is the layers of composites that give the strength. OTOH, wood does add strength. If you choose some kind of rot resistant wood, seal it and use wood strips, rather than foam, it would not be so much weight because you need less layers of composite.

    I would not use plywood, but thin strips of "grown" lumber, or swan lumber, steam bent perhaps if necessary, and epoxied in place, and glassed over.

    There are very light all wood canoes made, in fact traditional wood and canvas canoes are very light, and do not require a mold at all. A wood and canvase canoe also costs much less to build, you likely can find free plans on the internet. The only draw back is they should be stored out of the weather when you are not using them, or they will degrade very rapidly. Though even a fiberglass or kevlar canoe will break down faster if left in the sun and weather too.

    I like working with wood, even thought it can be more time consuming, and the hull is not as durable unless stored out of the water and out of the weather. But it is less costly and much more pleasant to work with, looks nicer too when it is finished.
  6. lyda
    Joined: Oct 2016
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    lyda New Member

    Kayaks don't really interest me - more interested in lakes than rivers. Plus most lakes in the west of Ireland have small islands on them so a place to stow things like tents, stoves and other such things would be a requirement.

    Still need to do more research on female molds - removing the canoe from one seems like the important trick. Having the mold in parts could be useful. But I think that's further up the learning curve for me.

    I've also read a fair bit about wood strip boats. There are loads of good videos on youtube as well. I have questions on those too!

    First you mention canvas and wood. I read about that but all the videos I've seen use fiberglass and wood. Usually a layer on the outside. The general idea seemed to be that it added stiffness and waterproofing, but elsewhere I read that varnish would do much the same job. Honestly it seems to me that fiberglass/resin would hold the strips together better, so wasn't sure.

    The other idea I had was that by only needing the stations and not the complexity of even a plug, it makes it a fair bit easier to experiment with boat shapes. Obviously you still have to go through the whole process of building a boat, but the time / money invested is a fair bit less.

    As for storage, I have a garage and can just hoist canoes into the roof - they'd even be out of the sun up there.

    And by the way, thanks for all the answers. This is all new to me so pardon if my questions reek n00b! Eventually I need to just pick a plan and a type and go for it, but it can take time to get things out here so knowing in advance what my options are and what the trade-offs are really helps.
  7. latestarter
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    latestarter Senior Member

    1 person likes this.
  8. SamSam
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    Location: Coastal Georgia

    SamSam Senior Member

  9. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Alternatively, buy a used canoe of the shape and length that you want.
    Remove the gunnel, use a release agent and build a fibreglass female mold, add in some longitudinal exterior stringers on the mold for rigidity.

    Afterwards sell the canoe and you have the mold that you want to begin playing around with Kevlar etc

    While some might say that you are stealing a design, but overall the shapes and performance of mid stream current canoes are not really that much different from one another and you are only building a one off. It is unlikely that your first attempt if you really want to build a plug-mold will result in a new design that will take you further per stroke than a proven design. But it is likely that your first attempt might give you a result that is less efficient than a proven design

    This way you could also try out the canoe if the seller will permit it to take it for short spin to check the stability etc
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