but if I paddle straight and set a good edge on either of my sea kayaks, assuming the wind isn't interfering, the bow will turn a bit.
As said above, it is hardly a complete turn. But it is enough to show that an edge can make or break a good turn.
Remember that this thread did not start asking if you should be executing turns just by leaning/edging, but which edge to choose. I don't think anyone has suggested skipping the sweep stroke to start one, or being less aggressive than needed. A lot of the responses, mine included, have been just on thoughts and behaviors that can point to which how the edging is likely to work best.
I think that some of the responses have gone further, essentially filling in the rest of the turn technique.
in flatwater with no paddle input - which way does your kayak turn? Is it the modified hull shape that remains in the water that makes it turn in one direction versus the other? Can't seem to get that link to outer-island working.
edit - that like is working now. That is a nice little description for sure. It does seem that the boat naturally turns away from the edge that is dropped but I am not sure I 100% understand why it does that. I remember seeing a drawing showing the shape of the hull in the water when the edge is dropped but for the life of me I cannot find it. That drawing might bring this more clearly into focus for me.
Easiest to just try it out Get going straight at a good speed, then drop an edge and see where you go. Obviously rudders and skegs up. If you see no directional change, however slight, it is likely due to wind, lack of speed, currebt or you haven’t really gotten the boat on edge.
This is getting way too theoretical - I agree with some above on that. Dropping the edge needs to happen fairly thoughtlessly in a pinch, and the only way you get that response is by doing it.
you can imagine that with a bit of heel the chine along the side of the hull could be dropped as deep or deeper in the water than the keel line and would have as much or more effect on the path of the boat as the keel line would.
But the keel line is straight from stem to stern and the line of the chine is dramatically curved along the side of the hull. So the boat naturally follows a path corresponding to the curvature of that chine.
You have a 12 ft row boat on the lawn. it's 4 ft wide. You're building it so there's no bottom on it. You lean it on the left side and push from the back. The left side of the boat is curved to the right like a curved road. The boat goes right.
but I'm challenged in this area so its probably just me. I guess if the boat has no rocker than yes, I can see that. But if a boat is heavily rockered than no - I can't visualize it.
I guess it falls into the category of one of those things I just need to accept on faith.
Seems that if your boat turns naturally to the off side then you are fighting its natural tendencies when you try to put it on edge and turn to the "on" side - like we were discussing with an eddy turn.
yes, you generally need some paddle to get the turn started. I’ve seen many others echo this same idea that edging itself normally isn’t enough. But with edging you generally only need a hint of a sweep to get a noticeable change in direction. I suspect most that might feel they can do only by edging unknowingly gave a wee bit more of a stroke on one side while or just before edging to help.
That is great! Thanks for that animation. What I take from it is that the shape of the hull in the water changes when it is edged. The side that you tip into the water is curved along the new water line but the other “off” side is straightened so you have a curve on one side and less of a curve on the other side. This also suggests that perhaps a highly rockered kayak would not turn so much because the off side hull shape might not straighten out so much when the boat is leaned.
If My Memory is Working… Flatpick wrote a good while ago that leaning the boat, either direction, essentially ‘breaks it loose’ and makes it easier to turn.
The proper term for lean/ edging is heeling - been used by navel architects for centuries - a temporary, induced list to beam. Heeling a kayak is best accomplished by keeping the torso erect and lifting with one thigh, which will also weight the opposite hip.
Heeling lifts the hulls stems, shortening the waterline length and increasing rocker at both ends which allows it to turn more readily. Heeling also changes the hull form, usually to a banana sort of shape curving away from the heeled down side. This generates lift towards the heeled down side, Paffett, but more importantly changed the bow's entry.
Unless the designer/builder have very eccentric ideas, most bow planes are equal port and starboard like a German kitchen knife is honed. With even keel and forward motion, water should exert equal pressure on both sides.
When a hull is heeled, the heeled down bow plane is forced downwards in the water, increasing pressure while the up side presents less surface to the water, reducing pressure. The kitchen knife becomes a single bevel wood chisel. The pressure or force differential forces the bow away from the heeled down side, starting a turn to the unweighted side.
From that point, most paddlecraft turns become skids as the bow moves off course into the turn and the paddler's weight, which stays on course, forces the stern into a skid. [Newton being pretty much right three hundred fifty years ago.] The induced offset between the CG, usually the paddler, which stays on course and a parallel line drawn through the rotational center is the Yaw Couple, the greater the Distance/ offset the faster the skidded turn.
We can induce a skidded turn to either side, by sweeping, drawing or stern prying the bow off course into the intended turn. Heeling either way will quicken the turn because heeling reduces waterline length and increases rocker, both lessening resistance to turning, but an outside heeled will initiate a turn without paddle input, and outside heeled, carved, turns are always faster than the more stable inside heeled ones because , without paddle input, that's where the bow wants to go and we preserve more momentum by not initiating with the paddle.
The above addressing hulls with stems in the water as OP mentioned, not WW craft.
Not exactly A highly rockered boat has less hull in the water to start with compared to a less rockered boat of the same length. So length of of hull in the water will be shorter, which means it turns more easily.
Again, just go paddle. There will not be enough time when you really need to turn to think about the physics.