which will paddle easier a canoe with more or less rocker? is there a fine line [limit] on what is considered too much or too little rocker going upstream?
Well look at it this way…
Imagine an 18 foot log and a round saucer winter sled. One represents NO rocker and the other a LOT of rocker. This in a sense is NO difference in boat designs to make a long story short. The main this it WHAT the water is coming in contact with…which is the sides of the above objects etc
Can racers during training often paddle upstream as it is EASIER to turn or at least QUICKER which results in ease due to the fact that going upstream is no different than going down with a much FASTER current…the same reason its easier and quicker to turn a ski on a snow slope going 30mph vs going 1 mph. Canoe racers canoes are usually 18 feet of long and NO rocker!!! Such as a Log! It will track very straight so your not spending 90% of each minute using enegy to keep the boat going straigt of using corrective stokes to do so…thus its less tiring since you “conserving energy” by being more effiecient. No imagine a sauser. It would spin around like an inner tube etc. You would be alway trying to keep yourself in a forward possisition. Get it? More rocker ='s quicker and ease of ease turn but also means MORE of doing that which ='s more tiring which is what most people who same more difficult. Thats the short answer. Now ideally is somewhere in the middle maybe for you? Depending on river, water flow, ability, and intent etc.
I have a decked canoe with a rudder installed (a rudder is the most effiecient thing you can put on a canoe or any boat for that matter i.e ocean liner to fishing boat etc) No more wasted energy trying to keep the boat going straight…all your energy and effort is making the boat go forward…get it?
I did plenty of upstream paddling last summer from St. Louis to Montana on the Missouri and could not have done it in a short boat. See more here http://www.lewisandclark-2004.com
When going up through rapids, some
rocker and some flatness on the bottom of the boat can make things easier. My best WW kayaks and C-1s for forcing upstream through rapids have moderate rocker, relatively round bows, and considerable flatness under the cockpit and toward the stern.
It is interesting to compare the WW downriver racing boats with the slalom boats. The downriver boats have virtually no rocker, and really are not flat underneath. They force up through rapids with displacement hull speed. Of course they do not adjust course easily, so if turning is required while attaining, they have problems. But they can go straight up some pretty fast chutes.
Slalom kayaks, C-1s, and open slalom canoes are not nearly as good for forcing straight up a chute, but their turning and wave surfing ability allows them to exploit weak seams in the downstream currents to get up over holes and ledges. Also, both my slalom C-1 and an old kayak I have, built along racing lines, have flattish undersides, and when paddling upstream, I can feel the hull “plane up” against fast downstream jets. This seems to make progress easier.
So, there are at least two different approaches to the problem. I will point out that the jet boats which attained all the way up the Grand Canyon and back were not long, pointy, displacement hulls, but were planing speedboat designs. The trick is, how much power does one have to take advantage of a planing hull? If one does not have enough power to make it plane where it counts, then one is better off with a no-rocker displacement hull.