Very perceptive
I planned to comment on this after a day or two. You’ve saved me the trouble.
Thanks
This shows the “goosing” technique
– Last Updated: Dec-21-14 3:56 PM EST –
For the prying sideslip, the slip can be extended by pushing the paddle forward. This will do two things: push (pry) the boat away from the paddle and slow the boat.
To maintain a perfect sideslip while goosing, the fulcrum ray must continue to intersect the pivot point. As the paddle is moved forward, the closing angle of the blade must be increased to keep the ray pointed sufficiently aft at the pivot point (which itself may be moving further aft as the boat slows under the peripatetic pivot point hypothesis).
Under these physics principles, a drawing sideslip should also be moved forward to goose the slip, and its open angle should be increasingly closed so the fulcrum ray can continue to be pointed sufficiently aft at the pivot point.
On edit: When goosing a drawing or prying sideslip, the paddler will not only move the paddle forward, but may also move the paddle closer to the centerline of the hull. This turns the static sideslip into a slightly dynamic slip during the goosing phase. Marc does this in the video by simply having his goosing pry phase follow the narrowing gunwale line.
Glenn, I do not find a drawing sideslip
moving forward with an increasingly closed angle to work at all. Based on the physics, it moves aft with an increasing open angle, which still has the ray pointing to the pivot point. And, actually when momentum is just about gone, the paddle blade can be just about perpendicular to the hull centerline and the boat can move laterally (definitely not pointing to the pivot point then) Of course, this illustration is for calm flatwater situations; not creeking.
Hmmmm
I admitted in my first “goosing” post way above that I was unclear on the practical and empirical method of goosing . . . mainly because I can’t hop in my boat to figure out what I actually do, and I’m getting a little confused thinking about it at the computer while making believe I have a paddle in my hands.
As to the drawing sideslip on a goose, I can see the fulcrum ray being geometrically in the right place to intersect the pivot point with either method–i.e., (1) by moving the paddle placement forward and closing the angle, or (2) by moving it aft and opening the angle.
I can now visualize it working your way (method 2) as long as there is enough forward speed remaining to create a drawing force on the power face of the paddle as you are moving the paddle aft. Do you also pull the paddle in closer to the keel line when doing this to add some dynamic drawing power?
For method 1, in order to increase drawing force with some dynamic draw during the goose, I was visualizing drawing the paddle in toward the keel while moving the paddle forward. This, of course, assumes the paddler starts and holds the static sideslip draw a good ways away from the gunwale, which some people do by arching the paddle way over their heads. One can also draw right next to the gunwale.
I’m sure you are correct in your recollection of your own technique. Kayamedic seemed to say that she gooses the drawing sideslip forward. The fulcrum ray intersection of the pivot point would seem to work either way, but that doesn’t answer the practical issue of which method is more effective. I’ll remain confused until April.
Oh, hold on, now I’m thinking about your distinction between moving and still water. Yes, I’m primarily visualizing what I used to do in whitewater, which I learned long before freestyle flatwater. When sideslipping to my on-side around a rock up ahead, I would start with a static draw held pretty far from the gunwale (because I’m using a much longer straight paddle than I do in flatwater). If the static draw doesn’t seem like it will move me far enough to the on-side to avoid collision, I then begin a strong dynamic draw to the gunwale. When doing this, my paddle travels diagonally forward and I close the face to grab more water (which also allows the fulcrum ray to keep intersecting the pivot point, though I had no understanding of that principle until I read Pat Moore many years later).
So now I’m thinking method 1 works when I have enough momentum to do a dynamic drawing goose in moving water, but that’s not the same situation as goosing out the last bit of draw via a static sidelsip in flatwater.
For those of you who have actually read through this ramble, I’m sorry your lives are so bereft of important things to do.
I wonder if the your drawing SS works
in WW because the “apparent” pivot point is further forward when you have momentum due to current? That’s what it seems like to me. anyway. I am thinking it would not work so well with decreasing momentum such as in a flatwater scenario as the point tends to shift further back.
“Momentum due to current”
– Last Updated: Dec-22-14 1:07 PM EST –
What really matters is the speed and direction of motion of the boat relative to the water that it floats in. A boat that's drifting at the same speed as the current is just as much "dead in the water" as one that sits perfectly still in a lake, as far as the dynamics of paddling go, and when making the boat move through the water, adjusting course relative to that water (not what most people in moving water are relating to, thus much confusion about this concept) is the same in either case. The only thing that's different in moving water is how you adjust what you do in order to account for your movement relative to stationary objects (true for any direction of paddling in current).
So, a boat that's moving 3 mph on still water should behave and handle the same as one that's moving 6 mph downstream on a river with a 3-mph current, except for complications due to turbulence (and out in the main flow, that's often negligible), and except for the fact that you'll be approaching obstacles at double your actual paddling speed. If you were paddling among a whole bunch of free-floating markers, how the boat maneuvered among those markers would be the same regardless of current. Some physics teachers like to illustrate this diagramatically to teach about frame of reference, but I'd love for someone to make an animated video (or a real one) that shows how the boat's perspective regarding the water that it's in is always the same.
Well, not exactly, practically
I take your main point as true, GBG, which you’ve made before.
It’s true that if I’m becalmed on still, flat water, putting my paddle into the water won’t have any force effect. The boat will stay still.
However, your idealized moving water comparison assumes a sheet of water always moving at a uniform velocity, and velocity encompasses both a speed and direction component. What if I stick my paddle into this idealized uniform sheet? Will there be a force effect on the paddle? I think so. The very act of putting my paddle in the water may change the speed or direction–due to a change in friction or the mass balance–of my boat relative to the water slightly. Any change in the speed or direction will be enough to generate a force on the paddle, which I can use to move the boat even more relative to the water.
Secondly, a canoe on a river is almost never going exactly at the the same speed and direction as the water, even assuming the water is a perfectly uniform sheet. Depending on the river gradient and the hull shape, a canoe can drift faster or slower than the current. You can test this by drifting next to a leaf. Hence, putting your paddle into the water while drifting will almost always generate some force because there will be a slight velocity difference (in speed or direction).
Finally, and most practically, virtually no river is a uniform sheet. It’s a roiling mass of eddies, swirls, boils, slower water and faster water – caused by changing depths and bottom configurations even if there are no obstacles on the surface. Thus, even if you are moving as close as possible to current velocity in some local area, I can probably stick my paddle into a different velocity zone within a few feet or seconds–which will generate a force on the paddle with which I can control the canoe.
Of course, none of this may be relevant to a static or dynamic sideslip. Except, I know I generally paddle faster than current velocity in whitewater than I do in flatwater, if for no other reason than that I usually paddle at angles in whitewater. Even assuming speed stays the same, angle paddling in current will change relative velocity when it won’t at all in non-moving flatwater.
No wish to expand on this much, but …
– Last Updated: Dec-22-14 2:33 PM EST –
... I will say a couple of things. You are correct that I was speaking of an idealized situation, simply to address the concept of the pivot point being affected by the boat's speed *through the water*, not by it's speed in relation to the surface of the ground.
However, ignoring turbulence, the idea applies more than you say. As to the idea that inserting the paddle blade when drifting at the speed of the current will make a difference, you should try it, a lot, and make sure there's no wind to confuse the issue. It only takes a very tiny amount of wind to have a consistent and predicable affect on one's experiments, and with practice, the sameness of any such wind when on a lake or river becomes clear.
Speaking of wind, air resistance will account for how you drift faster than a floating leaf, if you are lucky enough to have a windless day for making this speed comparison (think how much that leaf would move horizontally during any period of observation if it were falling freely through a 3-mph wind (same effect as floating on a 3-mph current on a windless day). That speed due to relative airspeed will be a bit slower when it's floating on account of friction with the water, but it's still noticeable. Watch the same leaf on the surface of a puddle and see that it moves over the surface no matter how slight the wind). If you pick a submerged leaf as your reference point and ensure your boat is going the same speed as the current (one way to do this is by planting your paddle and noting whether there's turbulence around it or whether it wants to move when held lightly only by the top grip), your boat and leaf will drift alongside each other pretty reliably. Of course, you will see variations in current speed and this kind of comparison can only be "close to perfect" when conditions are right, and even though "close to perfect" may not be the norm, applying this idea to turbulent flow misses the point (how to maintain control when the water isn't all moving the same is a whole other topic).
Note how submerged or mostly-submerged objects drifting with the current simply spin and/or twirl aimlessly with the slowly-roiling water (not ignoring that there's always turbulence for this example). This illustrates the lack of a net force, which is not possible based on your idea that inserting a paddle changes the current's effect. If one of these objects were to sprout a new protrusion, or if you laid a stick across one that's already been drifting (analogous to when a free-drifting paddler inserts a stationary blade), would anything change about the pattern of drift?
Remember, all of us are speeding up, slowing down, turning right and left, while walking, riding in cars, etc, all while riding the "current" of the surface of our spinning earth at several hundred miles per hour, and we can't perceive that motion at all. We can't walk in various directions and thereby deduce which way the earth's surface is moving, and neither can a ship on the ocean detect a strong current, and neither can a kayaker on open water in fog. We as river paddlers can detect the motion, but only because we have stationary objects to look at while doing so.
That's as much as I'll say, as this really isn't the place for carrying out an extended discussion of the topic.
OK - may be a stupid question, but…
what is goosing a sideslip - extending it as the boat slows?
Wow - worked my way through all of this
Great discussion. I know with a drawing sideslip that you move the paddle forward as the boat slows, but I don’t think it is because the pivot point moves forward. There must be another explanation to why that works.
More work re goosing
Yes, “goosing” is supposed to refer to prolonging the sideslip as speed slows AND keeping the slip perfectly lateral–i.e., not allowing the bow to yaw left or right as you slow way down.
I’ve refined my views as a result of this discussion. I now think the lateral goosing of a static sideslip is CAUSED by rotating the blade attack angle so that more of the blade is biting the water. More bite results in more draw/pry at the cost of further slowing of forward speed. This would be done by further opening the angle during the goose of a drawing sideslip and further closing the angle during the goose of a prying sideslip.
However, if you change the blade’s attack angle, you will change where the fulcrum ray is pointing. To keep the ray pointing at the pivot point as the attack angle is changed, so as not to induce bow yaw, the paddle must be moved at the same time in the fore-aft plane. This explanation requires the paddle to move forward to goose the prying sideslip and aft to goose the drawing sideslip (as Canoeist11 reports is his experience).
So, I’m sort of changing my causal story of what happens during a goose of a static sideslip. Changing the attack angle of the blade is the big dog, while moving the blade fore or aft is the necessary tail.
I think we can assume the pivot point doesn’t move much, if at all, as a canoe slows. No theory suggests the pivot point moves forward as a hull slows. The “peripatetic pivot point” theory, which is controversial, says the pivot point moves forward when a hull begins to move forward from a still position and then moves aft again when the hull slows.
Goose= Running Pry
– Last Updated: Dec-23-14 10:22 PM EST –
Glenn's "Goosing" has been called a "Running Pry" for over a century. William of Ockham, of Occum's Razor fame, suggests adding additional, unneeded, terms confuses rather than clarifies.
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Goosing
I like goosing better-it’s a funner term.
Turtle
A last word on fulcrum ray/pivot point
Some have voiced confusion over the concepts of the fulcrum ray and pivot point and how they interact. To understand these concepts requires no math at all and only the ability to imagine some simple mental pictures about points and lines (rays)
Let’s forget the word “fulcrum”. That only relates to the paddle’s being a lever, which is irrelevant to the issues of draws, pries and sideslips. Just think of an imaginary ray or line projecting out from the center of your paddle blade.
The pivot point (center of lateral resistance) is easy to picture. It’s just a point approximately in the center of the canoe.
Stand in the water next to the right side of a still canoe. Assume the pivot point is right at the middle of the center thwart. Pull against the gunwale with your finger directly aside the thwart. The canoe will just move perfectly laterally. It won’t pivot. It won’t yaw. It won’t turn. It will just move perfectly sideways.
Now pull at a place forward of the thwart. The bow will pivot (yaw, turn) to the right. Now pull at a point aft of the thwart, and the bow will pivot left.
The same thing will happen if you push against the side of the canoe instead of pulling.
Physics law: A (pulling or pushing) force directed in a line directly through the pivot point will move (draw or pry) the canoe perfectly sideways with no pivoting.
Practical lesson: To locate the pivot point, find the place where a pulling or pushing force against the side of the canoe won’t produce any pivoting.
Now get in the canoe to do a dynamic draw on the right side while the canoe is at rest. “Dynamic” (or “kinetic”) means you are pulling the paddle towards the boat. Stick the paddle in the water on the right and draw it toward you.
Imagine the canoe’s pivot point is now right at your belly button. Also keep imagining that ray projecting straight out from the paddle blade.
If you draw the blade such that the ray is aimed right at your belly button (the pivot point) the canoe will be drawn perfectly sideways with no pivoting. This is exactly the same force scenario as when you pulled on the gunwale with your finger. If you aim your draw (the ray) slightly forward or aft of your belly button, the canoe move sideways but the bow of canoe will also pivot, respectively, to the right or left.
That’s it! No math. Just some mental pictures about where the paddle blade ray is pointed.
Practical lesson: If you are doing a right handed dynamic draw and the bow turns right as the canoe moves sideways, you have aimed the drawing paddle too far forward. In other words, the paddle ray is forward of the pivot point. If your bow turns left instead, you have aimed the drawing paddle behind the pivot point.
Now back to the sideslip, which generated all this fancy sounding but really easy discussion.
The sideslip uses a static draw instead of a dynamic draw, and the boat must have forward motion. You stick the paddle into the water off to your right side and just plant it there–still, statically–without pulling toward the canoe.
To generate a drawing force you must angle the leading edge of the blade slightly, toward one or two o’clock. This is called an “open” angle. The force generated by the water dragging on the paddle will move (draw) the boat to the right. Good.
But will that force also turn the bow? No, not if your paddle blade (ray) is pointed at your belly button, which we have assumed is the pivot point. But note this picture: Since your paddle blade has a slightly open angle, you have to position the blade aftward of your belly button in order for the ray to intersect your belly button. Hence a static draw sideslip may need to have the open angled blade positioned at or behind your hip.
Practical lesson: If your right sided static draw sideslip is causing the bow to turn right, you have aimed the paddle (ray) too far forward. The ray is ahead of the pivot point. Either close the blade angle a little or move the entire paddle further aft with respect to your body.
All the same principles apply to the push force situations of the dynamic pry or the static pry sideslip.
(Charlie Wilson may be interested in knowing that a well-cooked goose was a favorite short meal of William of Ockham.)
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The Christie
– Last Updated: Dec-23-14 9:07 PM EST –
is the final "basic" freestyle maneuver. It is another on side turn (toward the paddle side).
The initiation is similar to the post or the axle (typically a strong J stroke). This nudges the boat in the correct direction. The J is followed by a palm roll, so that the power face is now essentially flat on the water, trailing near the stern. Substantial pressure is maintained on the blade (pressing downward). The shaft is as nearly horizontal as can be maintained. The grip and shaft hands are both out past the gunnel. This is necessary to keep the blade "flat" to the water.
As the turn slows, the leading edge of the blade is lifted slightly and a low braced, reverse sweep is initiated. As the reverse sweep approaches the blade being amidships, the blade is turned vertical (leading edge up). The classic conclusion is to continue the reverse sweep to the bow where the blade will be in position for the next forward stroke. In functional situations, the conclusion may be shortened, before the blade reaches the bow. It's a matter of how much rotation is required in any particular circumstance.
A second palm roll occurs during the reverse sweep sequence. The combination of the 1st and 2nd palm rolls allows for continuity of the power face against the water, throughout the maneuver.
More so than with the previous maneuvers, this one is more easily demonstrated than described.
Christie Videos
The two videos shown below were taken from a stern mounted camera. I don’t believe I have any Pine Barrens or similar videos showing a Christie in use.
Christie at normal speed
http://www.youtube.com/watch?v=Zf2-7UcFw60&feature=youtu.be
Christie at 1/4 speed
http://www.youtube.com/watch?v=NEV6r4kr76A&feature=youtu.be
Low Brace Christie
– Last Updated: Dec-23-14 10:33 PM EST –
Good description of the Low Brace Christie!
It was developed by Dana Grover, [from moves originally used in eddies on the Tigris River 4500y.a.], to crank Sawyer Solo Touring boats into eddy turns. The long tapered bows of touring boats, mostly Savage and WeNoNah now, do not want to draw towards the paddle, particularly when that paddle is a short bent with power pulse located back towards a wide, delta shaped aft section.
So if the bow won't swing the stern must skid. We do this as Marc suggests above, a powerful J starting to swing the stern, then palm rolling into a powerful stern pushaway, the top hand across the rail as the hull is heeled to the rail. The stern skid is continued with another palm roll into a reverse sweeping low brace. The Christie is complete when the paddle comes abeam the paddler, but in solo paddling we often palm roll again while bringing the top hand high into high brace configuration. The obvious solo draw to the bow merges into a forward stroke, which draws the bow into the eddy; all useful as we almost always enter eddies to low.
Tandem stern folk use the same Low Brace Christie when the bow employs a cross draw, but the maneuver ends when the blade comes abeam the paddlers body. Again, a forward stroke drives the hull safely into the eddy.
As the canoes were touring boats, bent shafts were the tool, and the Low Brace Christie was focused on bent paddles, the bent improving the reverse sweeping low brace to secure, bomb proof blade angles. The Christie works less well with straight blades, the angle compromises the reverse sweeping low brace.
The heel helps free the stern's skid but less heel than to the rail is indicated when tripping gear might get wet. The main addition I'd make to Marc's intro, is the violence of the pushaway. The bow is mostly stuck so we need to power the stern into a swing around that bow, hence heel and push!
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a lot going on there
but the gist of it is a “hangin” brace, saw a little pry in there as well,reverse sweep and mostly movin’ the strokes toward the ends of the boat to help with turning. There’s a bit of the clip where the paddle blade is passing under the hull- tend to stay away from that in moving water/whitewater situations and I’m less about the in the water recovery and linking it all up but that was what made it so pretty to watch-kept it fluid. Didn’t know it was called a “Christie” but I do paddle sometimes with a gal called “Christine.”
The videos
– Last Updated: Dec-24-14 1:59 PM EST –
The videos, while nicely done by a skilled paddler, illustrate the twin problems with using a functional Christie in freestyle boats with straight paddles.
The highly rockered bow swings readily into the maneuver so the rockered stern skids around in a disinterested manner, the hull completing a 90 degree turn before the paddler can apply a forceful reverse sweeping low brace. Straight paddles compromise the bracing angle, and thereby the extended heel. Hence no strum and drang! Solo FreeStyle Christies are pretty boring to use or watch and often amount to setting the boat up skid onside and posing with the paddle. Jeff Liebel has a paddle posed Christie where he lays the paddle against the boat, it follows the stern's skid hands off. We need longer boats with less rocker, a bent paddle and POWER.
Functional purpose of Christie vs. axle
This is a “why” question simply to elicit information.
As this is a functional freestyle thread, what function does a Christie turn serve versus the axle turn? Both are initiated with a pry or pushaway. Both have a hanging draw (Duffek) in the middle. Both have the hull heeled on-side. Both can be concluded with a bow draw.
The difference seems to be the sweeping low brace in between the initiating pry/pushaway element and the hanging draw element. What functional purpose does that serve? On thing that comes to mind is that it would probably slow the boat.
Maybe Charlie Wilson has answered this question with the suggestion that the Christie can more effectively turn a non-rockered hull. Is that correct? Is there more?
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