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Thread: Stabilizing canoe

  1. #1
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    Stabilizing canoe

    A few years back I built a cedar strip canoe. It turned out pretty well with one exception; it is very unstable. Because of this, I seldom use it and it hangs in the garage collecting dust. Does anybody know of any tricks that I can use to stabilize it?
    Torre

    A lack of thoughtfulness is different than a lack of intelligence, but often has the same net result

  2. #2
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    You could try adding a heavy keel/skeg, though to have much effect I suspect it would use up a lot of the floatation capacity of the canoe. Unfortunately, most of the stability of a non-keeled boat comes from the shape of the bottom, which can't readily be altered after it is built.

  3. #3
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    +1 on the hull shape. Depending on the design your canoe may have low initial stability however once it heels some it may "dig in" for more final stability.

  4. #4
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    If you had seen the maiden voyage, you would know that the final stability is not very good either

    Maybe I'll sell it for a decoration (anyone got a big living room), and build a new one.
    Torre

    A lack of thoughtfulness is different than a lack of intelligence, but often has the same net result

  5. #5
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    I guess it's safe to rule out pilot error. Have you tried lowering the CG? Maybe your seats are too high. Of course you could add a couple of outriggers and a sail and have a very nice sailing canoe. Lots of resources on the net for doing just that.
    Last edited by Jim Creech; 04-24-2012 at 2:56 PM.

  6. #6
    How about a set of Sponsons? Certainly won't help the slippery shape of your hard work although if done right will really improve the stability. Actually if you use (2) well positioned and proportioned foam cores attached to the Canoe and cover them with additional matching wood strips,glass, epoxy, It would look as it was designed this way from the start. The tough part IMO would be to blend the Sponsons into the existing Canoe hull.
    Good luck,
    Mac
    Last edited by Mac McQuinn; 04-25-2012 at 12:00 PM.

  7. #7
    Speaking purely from a dynamics standpoint, the problem is that the bottom of the canoe is all roughly equidistant from the center of bouyancy (CoB). If the CoB is closest to the hull when the canoe is level, but the shape of the hull results in the hull getting rapidly farther away from the CoB as the canoe heels, the canoe will be very stable. For an extreme comparison, imagine a log which as all parts of its bark (hull) roughly the same distance away from the CoB. Spins like a prop shaft. Contrast this to a barge, who's extreme width and flat bottom mean that the CoB is closest to the hull when the barge is dead level. Because the corners of the bottom of the hull are quite a long ways away from the CoB, even a few degrees of heel results in a very strong righting action.

    So, you need to change the shape of your hull. Could you sand off the finish and add bulges right at the waterline to each side of the canoe, fill them with foam, and then fair them smooth to the rest of the hull? It would sort of be like the external fuel tanks in the picture below but molded onto the hull rather than separate.

  8. #8
    Best idea would be an ama, and make it into a paddling proa, or even trimaran. This, unlike some of the other suggestions, is an actual boat type.

    What design did you use? If you built to a proper design, maybe you need a paddling course, if you built to your own design, then you need to get some data on board before you try another. I have a file somewhere that gives basics factors for canoes. It is actually surprisingly close to 100% crossectional area, when compared to other boats. If you stick with the correct factors, and otherwise normally configure it, it should turn out fine. When I first got my hull design program, about 20 years ago. I turned out some designs that looked correct. But when I ran the factors, they were in Kayak stability range. Saves making mistakes.

    By the way. There are quite a few canoes that people have difficulty keeping upright when they first get into them. While any such boat may not be idea for family fun, it is possible to learn to paddle some pretty barrel sectioned boats. It helps make it worth while if they are fast, or somehow otherwise redeemable.
    Last edited by Roderick Gentry; 05-26-2012 at 3:17 AM.

  9. #9

    Hull design

    Quote Originally Posted by PeterTorresani View Post
    A few years back I built a cedar strip canoe. It turned out pretty well with one exception; it is very unstable. Because of this, I seldom use it and it hangs in the garage collecting dust. Does anybody know of any tricks that I can use to stabilize it?
    What design did you use? Give us the canoes specs and all will be revealed. Canoes are like golf clubs, each one has its parameters. A great white water canoe blows on an open lake and a lake canoe will never be a nimble craft in the white water.

    The Chestnut Prospector does all well but excels in no one situation except for versatility. A gold standard in canoeing because it does all. It is most stable when soloed and the one gunwhale is inches from the water - hull design!

  10. #10
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    http://homepages.paradise.net.nz/garyd/quikama.html

    ya an Ama !! ... that would be the easiest with out destroying or practically building another boat.+ you could always hang it with out them and look at it while drinking your wine.

  11. #11
    I don't think the prospector is a gold standard for modern conoeing. I was designed to work well in a load condition that is far from what modern trippers use. As a result the boat has been redesigned many times to meet various ideas of what the ideal Prospector would be. We are pretty far from the source at this point.

    The prospector is iconic as the boat that Bill Mason used in many movies, but he was a guy who wrote about canoeing, not one who set the standard on boats or paddling.

  12. #12
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    Old thread but I do not see the answer the answer I was looking for so..

    Typically canoe hull designs lean towards 1)low volume, narrow, thin hulls for speed and straight tracking on flat water, or 2)"bathtub" hull shapes that spin and turn in either direction for white water. The two hull designs have opposing features. Almost no one likes a slow canoe. Often initial stability is sacrificed to obtain a hull shape that tracks a straight line and moves reasonably fast but can still be turned without Herculean effort. It is tough to design a beginner hull, a stable hull is typically an absolute pig once the paddler starts developing more skills.

    Someone mentioned initial vs final stability, a key point that our OP misses because he does not grasp the key ingredient. The ability of the paddler is the major factor in more advanced/compromise boat designs. I have a very small canoe which is built to turn fast and reach hull speed quickly too. Most people, even those with advanced skills, turn the boat over a few times getting into it, before they learn the delicate balance built into the design. It tracks fast on a hull that is very V shaped at both ends. To turn the boat one has to lean the boat over until the gunnel almost sinks under the surface (0 initial stability, final stability requiring advanced paddling technique). The sides and edges of the hull are turn friendly. It takes practice to learn to turn a boat leaned 45-90 degrees to the water's surface. The key ability of a person who can use a boat like this is the ability to lean large amounts of weight out on the paddle while paddling. The paddle becomes sort of like an outrigger.
    Last edited by Mike Holbrook; 07-15-2013 at 2:02 PM.

  13. #13
    Peter, just thought I would add some thoughts in case you didn't get the answer you needed.
    Mike hit a few good points. Different canoes operate differently. Initial and secondary stability is a tricky thing and I wouldn't rely too much on what that means as there are too many variables to consider to be of real help to a paddler. For instance is it calculated for a solo paddler in the center of the canoe or two paddlers and if for two paddlers then is it for the front paddler or the rear. The calculations will vary for every variable you input and in the end it means nothing to someone who simply wants to go paddling.

    That said, canoes are in fact designed to accomplish different objectives. Typically a "tippie" canoe excels at speed and control. The trade off for that is the paddler placement is more critical than in a large lake canoe.

    I am in one way or another connected with thousands of canoe builds and I can tell you from experience that assuming that the design is solid, there are two reasons a canoe would be tippy. First, if the canoe is a sleek design, the seats need to be closer to the center of the hull where it is widest and they need to be low. On a cruising canoe, with a breadth at about 30" to 32" you should expect your seat to be only about 8" off the bottom of the hull and typically you will find yourself on your knees more than on your backside when paddling. Again, this isn't a bad thing if the canoe is specifically designed for this. It means it is made to move fast and straight.

    The second and more unfortunate reason would be a canoe being used in the wrong environment. I cannot tell you how many times I have spoken with people who have built a river canoe to use on lakes. By design this at best will be a bad trade off. Many years ago, there was a book published which called the Chestnut prospector a good all around canoe and this is simply not the case. It has a great deal of rocker, high sides and tumble-home you would expect to see in a river canoe. Because of all of this it is an excellent river canoe. I have used it myself on many rivers. Unfortunately all of these things make it a horrible lake canoe and it is just flat out sad when someone builds that canoe for lakes.

    Bottom line is if you are still having trouble, by all means give the designer a call if they are around and ask them for help. If they are not around, go ahead and give us a yell and we will try to help you out. You can contact us at www.sandypointboatworks.com
    Jackbat

  14. #14
    I agree on your assessment of the prospector. Though, the modern day incarnation is popular due to movies and books where it was being paddle in some part on lake superior. Well, I suppose you would be dead lucky to find that looking like flat water. Canadians have developed a whole paddle craft around these things.

    The point about the seats is a good one. If one is soloing in a tandem, the old flip it around and paddle from the front deal, can get you in the water a number of ways. If it is a solo problem then moving to the center is a good idea. A couple paddling where he weighs 250, and she weighs 100, might as well be a solo. Once the boat is being paddled tandem on it's lines, you can be out in the tippy sections of the ends, and yet you are ridding the max station in the middle somewhere. At that point having your seats out there where you can more easily manoeuvre the boat, or reach the water, may be fine.

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