White Coat Underground

No, I’m not tipping over

If you look to your left, you may notice me paddling a black and white cedar-strip and canvas canoe. I am not about to dump into the water—the “lean” is proper solo canoeing posture. A few years decades back, I was the canoeing director at a Canadian summer camp and taught hundreds of kids how to paddle a canoe. Since this is a “science blog”, I’ll explain this awkward-seeming posture to you.

The proper position for traditional Canandian-style solo paddling is half-way between the bow and the stern, leaning to the side you paddle on, preferably on your knees. The lean itself accomplishes two things: it brings you closer to the water, making paddling easier, and it lifts a substantial portion of the hull out of the water. Less hull in the water means less resistance to forward motion and to turns. You kneel, rather than sit on the (decorative) seat so that you have a low center of gravity and wide base of support—canoes are rather tippy vessels.

Once seated thus, paddle in hand, you can achieve complete control of the canoe. The position described puts you at the fulcrum of the canoe, and your paddle is a powerful lever. To pull your paddle straight into the canoe is called a “draw” (the opposite of a draw stroke is often called a push-away). If you draw right at the fulcrum, you will move (approximately) sideways. If you reach behind you and draw, you will pivot the stern of the canoe toward your side, turning the canoe to the “outside” (away from your paddling side). Reach forward and draw, and your canoe pivots the other way. You may wish to refer to my well-rendered schematic.
i-6a0d1e11e30a839be7b67ed7b35a8cdd-canoe mechanics.JPG
Understanding the pivot allows you to move forward in a straight line without switching sides. A standard forward paddle stroke (known as a “bow stroke”) turns you to the outside and makes you look rather silly if your objective is forward motion. A deceptively simple twist of the paddle at the end of a bow stroke turns it into a J-stroke. The end of the J-stroke is a “push-away”, so the first part of the stroke turns you to the outside, the last part pivots you back to the inside. When executed well, the result is smooth, forward motion.

While achieving perfect control of the canoe may take a while to master, the basic concepts are reasonably simple and easy to build upon. For example, when paddling into a strong wind, it often helps to move yourself forward in the canoe, allowing the bow to “cut” through the waves (also increasing the drag so that the wind doesn’t push you around—a sort of “flag in the wind” phenomenon). With the fulcrum moved forward, however, you must reach much further backward with your J-stroke in order to go straight.

With just a wee bit of science, you can figure out how to make a canoe do what you want it to. How cool is that?

Comments

  1. #1 Chris
    July 22, 2009

    That is way cool. I bet that it takes lots of practice to execute that without wobbling or tipping over.

    I did actually recognize that you were not tipping over because I had seen that type of canoeing before. When my soon to enter college son was in 7th grade he attended an after school paddling class at a nearby lake. When I picked him up I saw the kids learning how to do those strokes, and try to keep a racing canoe balanced. It was tricky. My son did decide after that class that he preferred canoes to kayaks.

    Thanks for the explanation.

  2. #2 Dunc
    July 23, 2009

    Nice looking canoe! Solo Canadian rocks – I’ve never understood the attraction of kayaks, even though they’re vastly more popular over here (UK). A well-executed J-stroke is a thing of beauty.

    It’s been ages since I’ve been canoeing. Must do something about that…

    How’s your Indian stroke? ;)

  3. #3 Ian
    July 23, 2009

    It seems to me that this is nothing more than a fix for the bad designed of the canoe. Why not design the canoe from the outset to take care of these things?!

  4. #4 Dunc
    July 23, 2009

    Why not design the canoe from the outset to take care of these things?!

    Because then it wouldn’t be nearly as manoeuvrable. Manoeuvrability is one of the key advantages of the Canadian canoe, and part of the reason why it is such a successful design. You can spin a canoe on a dime. If you couldn’t, you wouldn’t be able to “break” out of fast-flowing water into an eddy, which is pretty much essential for not getting smashed to bits in rapids.

    Any design that’s been in continuous use by many different cultures with vastly different technological capabilities for thousands of years clearly has something going for it. I’m of the opinion that the Canadian canoe is the finest small watercraft ever devised, and the basic design really can’t be improved on. It’s perfect – it just requires a little skill to use properly.

  5. #5 PalMD
    July 23, 2009

    My “indian stroke”, also known as the “silent J” is, of course, silent and flawless.

  6. #6 Rosenschlect
    July 23, 2009

    PalMD — Nice job describing the physics of canoeing! As one of the people who taught you how to paddle back when — and I still try to get out on a lake as often as I can — you know that I share your love of it! (So how are your knees and ankles doing?)

    Re designing a boat that didn’t require the techniques that Pal describes — it would require that you paddle directly behind the canoe (physically impossible; you would fall out of the boat) or directly underneath the center of the canoe (maybe scientifically possible to create boat that has a way to paddle underneath the canoe in a way which would make the canoe go straight, but then you need some other mechanism to enable you to turn).

    Bottom line, I agree completely with Dunc that the design that we have is elegant and simple and allows for total control and ballet-like maneouverability — why mess with success?

  7. #7 PalMD
    July 23, 2009

    @rosenschlecht

    Yeah, thanks for all that!

    And yeah, my knees and ankles are not happy campers, but I still paddle mostly on my knees.

  8. #8 Dunc
    July 23, 2009

    One knee or two? I’m generally a “one knee” kneeler – if that leg stiffens up too much, you can always swap. Although I’m mainly a flat-water paddler… I guess two knees is the way to go for rougher waters.

  9. #9 PalMD
    July 23, 2009

    I only get up on one knee in rough weather when i need extra reach

  10. #10 Eofhan
    July 24, 2009

    I saw a canoeist (alone in an 18ft aluminum craft) flip in a quiet stream. He was kneeling at the stern, bow was out of the water. Entering an open area from the trees, a cross-wind caught the bow and dumped him (no injuries, just a damp ride home). The position you describe exposes a considerable amount of the high side to the air. I wonder if it would be “tippier” in a wind. Do you remain kneeling to the side on a gusty day, or move to the center? (I get that moving forward lowers the bow, but that’ll make the bow into a pivot if the high side is also windward — a less extreme version of what happened to the stern in the accident I witnessed.)

    I’ve seen people doing this, and assumed they had a good reason, but never understood it. Thanks for the explanation.

  11. #11 Dacks
    July 25, 2009

    Back when I was studying for my master’s license, I learned a little about righting moments and secondary stability. The concept, which is easily observed by anyone who has spent time in a canoe or on a sailboat, is that a boat will heel to a certain angle depending on hull design, but that it requires significantly more force to push the boat over towards capsizing (This doesn’t take into account wave action.) A sailboat is actually happier when heeled to this optimum angle: it has a longer waterline which allows better maneuverability and more buoyancy from having more hull in the water. At least that is how I understand it.

    Canoes are such a beautiful design, in that they become more stable when loaded. I’ve really noticed it with our ultra-light kevlar canoe, which carries 100 lbs of camping gear and ourselves comfortably, but has a bit too much freeboard and too high a center of gravity when we take it out unloaded.

  12. #12 Rosenschlect
    July 27, 2009

    In answer to Eofhan’s question, you certainly do vary where you sit and how much you lean depending on the wind and the weather. The situation you describe — one person sitting in the stern of a canoe on a windy day with the bow high out of the water — would cause the canoe to act like a weather vane. If the paddler had enough balance to stay in the canoe and not end up in the water, the canoe would spin around so that the paddler would be facing the wind and the bow (high in the air) would be trailing behind him. In an extreme situation, you can actually use this technique to paddle into the wind on a high wind day. Bottom line, you need to be conscious of all that is going on around you — are the lake and the wind calm or blown up? which direction are the wind and the waves coming from? — and adjust what you are doing and (to a degree) where you sit accordingly. The picture of PalMD above is on a nice calm day, and he is taking advantage. I’m jealous that he got the opportunity in a place that we both love.

  13. #13 physics
    August 4, 2009

    Due to displacement no matter where you sit the same amount is still in the water, this way has more wind resistance and lower freeboard. that makes it slower and more prone too tipping.( and looks like you’re stupid)

  14. #14 PalMD
    August 4, 2009

    Blah blah blah. You’ve clearly never paddled a canoe properly. And don’t you quote me Archimedes, whippersnapper.

  15. #15 Whitecoat Tales
    August 4, 2009

    @Physics,

    What measure of “amount” are we using? Volume are, surface area, or some sort of effective cross sectional area?
    My physics is very rusty, but it would seem to make a difference.

  16. #16 PalMD
    August 5, 2009

    WcT is correct. If the volume displaced is shaped like a long, narrow vertical rod it behaves differently than if it’s a sphere of like volume.

  17. #17 PharmacistScott
    August 5, 2009

    Nice J stroke. I had no idea that there was a Canadian-style way of paddling a canoe. I thought that was just the way anyone would do it. Is there an American-style as well?

  18. #18 PalMD
    August 5, 2009

    Yeah…switching sides like an idiot!!!!