I have noticed that the different canoes I have had all had a different optimum cruising speed. Paddling at a speed less than that speed actually takes more work, because the craft is not as high in the water, and therefore displacing much more water when moving forward. We could paddle faster than the optimum cruising speed, but it takes much more energy to maintain the increased speed. Do paddling craft have a planing point where maximum efficiency is met, and best maintained? Maybe that could be tested and put on a sales label as OCS, Optimum Cruising Speed. Thanks for your thoughts.
Even though My Jensen goes faster then my Merlin, if you put Redcross Randy in them they go faster still. The vagauries of an individual paddler would make it pretty hard to quantify.
Generally for ease of paddling I look at what is winning at a race, and what every one else is paddling.
Just my opinion.
Makes no sense to me
First of all, I've never seen a canoe up on plane unless it had a gas outboard of 4 horsepower or more. Second, if what you say is true, a TRUE planing boat powered by a motor could cruise along at full throttle, gradually reduce power, and reach some point while reducing power where the speed actually increased instead of decreasing. Does that make any sense?
The same is true of any paddling craft. Pick ANY speed that you want to go and hold that speed using your GPS. Now reduce your paddling effort just a tiny bit, and what does the GPS say happens to your speed? Who ever imagined there might be a point where you could reduce your paddling effort and do the excact opposite of slowing down?
Here's what I think is happening. In actual fact, the effort needed to increse your speed increases exponentially relative to your actual speed increase. As you approach your boat's top speed, getting ANY additional speed at all takes a HUGE increase in effort. By the same token, if you are cruising at such a speed and back off on your paddling effort, your speed does not decrease anywhere nearly as much as you'd expect based on your reduction in power-output alone. I think the subjective feel of this phenomenom has fooled you into thinking less effort lets you go as fast or faster than the speed you go with more effort, because the change in effort is huge and the change in boat speed is so tiny. Again, check this against your GPS and you will find it to be true.
There are published charts (I can't remember where I've seen them) which show the force required to make both displacement and planing boats move at various speeds. Actual forces will depend on the boat being tested, but the one thing you can count on in those charts is that the propulsive force always increases with increasing speed. In short, for a given boat design, equipping it with a bigger motor or stronger paddler will ALWAYS make it faster.
You think your canoe is plannng? Try paddling a river with lots of shallow sandbars at various speeds. You'll find that the only way to get across the shallowest sandbars is to go at a dead-slow crawl. Anything faster and you'll drag bottom. In fact, on those sandbars, if you are paddling really fast, you'll hit so hard that you stop dead in your tracks. A true planing boat wouldn't do that. I've seen the same thing happen with rocks and logs that are very near the surface, so it's not just a matter of the boat's wake interacting with the river bottom. Of course, this is an issue involving trim as , since it's the rear half of the boat that will hit bottom in the shallows when you are going fast. Trim your boat so it is level when going fast and it will be bow-heavy when going slow, so this example isn't perfect.
Mysteries of water displacement and
forward movement of paddling craft have gotten us thinking about some concepts, and I doubt that we will be able to absolutely define them all as being understood.
When I used the term “planing”, I was referring to the effect of required paddling energy decreasing at a point where the paddling craft reached its optimum cruising speed. I have experienced this with all paddling craft I have been in, except the first I owned, which was a plastic barge type of craft. That plastic barge canoe had no optimum cruising speed, and incidentally, it also had virtually no glide to it when the paddling effort stopped. So, I think the amount of forward glide that a craft displays in momentum will correspond to its OCS.
Again, this is only my conceptual conjecture, as I have no proof of my theories, and am actually seeking some other opinions from anyone who has wondered about such things similarly. I would think that there are some hull designers who have experimented with hull designs and who have mastered some knowledge, but they probably keep them as “secrets of the trade”.
I agree with you about the draft of paddling craft being at minimum when moving slowly, and that makes me wonder what the draft actually is at OCS. A way to find out would be to buy a see thru canoe, mount a tripod in the middle of it with a camera facing the hull, and take some pictures of the waterline at various speeds while paddling. I’ll be sure to post the pictures and documented results when I have them.
Thanks for your posts, and keep thinking. It helps to have some understanding of the dynamics of the paddling experience that we enjoy so much. Happy paddling!
Displacement V Planning Hull
I am not a naval arch but I have read a lot over the years about hull shapes and work required to move those hulls. There are two basic shapes which react differantly as the move through the water. There are some hybrids that attempt to mix the two. Most canoes and kayaks are displacement hulls which means, amoung other things, than they do not come up on plane when paddled. A displacement hull has a predictable hull speed. The work required to move a displacement hull at various less than 100% values of hull speed represents a curve that approximates a linear picture. To move a displacement hull beyond hull speed requires a much steeper increase of work applied. It might as an example take two times the effort or work to move a displacement hull at twenty percent beyond the predicted hull speed. The advantage of a displacement hull is that it takes a lot less work to move it at hull speed as compared to moving a planing hull at the same speed.
An example that relates to paddling hydro-foil kayak things that are around. When up on their foil they are very quick but the power required to get them up is great. Ordinary folk like me cant paddle hard enough to make them plane.