The efficiency of bent vs. straight shaft paddles

[yknpdlr]

If there is no significant speed advantage, someone has to please tell me why in every one of hundreds of canoe races I have been in or seen, 95% of canoe racers adopt using bent shaft carbon paddles and will finish well ahead of 95% of (mainly first time racing beginners or "tourist paddlers" in the race) who paddle the race using straight wood paddles.

 

[Alan Gage]

If there is no significant speed advantage, someone has to please tell me why in every one of hundreds of canoe races I have been in or seen, 95% of canoe racers adopt using bent shaft carbon paddles and will finish well ahead of 95% of (mainly first time racing beginners or "tourist paddlers" in the race) who paddle the race using straight wood paddles.

In the races I've attended there is a very small percentage of truly top tier paddlers and they often finish very close to one another, sometimes seconds apart after an hour or more of racing. I don't doubt that a straight vs bent shaft might be the difference in them winning or losing but I still don't think it makes a significant difference and I certainly don't think the reason they're beating the 1st time "tourist paddlers" is because the tourist paddlers were using straights.

If you gave those top tier paddlers straight paddles and gave the rest of the field, even the middle of the pack paddlers (who are no slouch), bents I don't think there would be any difference in the final standings. The top tier paddlers are still going to win, straight or bent, over the rest of the field. The athlete is much more important than the equipment.

I have yet to see anyone that's made a compelling comparison between bents and straights to show that there is a significant (or any) difference that would matter to someone paddling at a tripping or leisurely pace. All the comparisons and studies I've found have compared short bent shafts to long straight shafts. That is if they even did make an actual comparison rather that using models to predict performance in a lab environment.

Alan

 

[yknpdlr]

The subject of recent posts was whether bents were 2.4% (or more) faster than straights. My point above was that it doesn’t take long for a new to racing paddler, wanting to eventually place well, will soon adopt use of a bent paddle in future races. Why?

If all in some odd race were required to use straight paddles only, of course there is little doubt that experienced race paddlers, top tier or middle pack paddlers, would still be the winners above the tourists who are not otherwise well experienced or have trained as race paddlers. i have never seen top finishers complete a race using anything other than a bent.

 

[Alan Gage]

The subject of recent posts was whether bents were 2.4% (or more) faster than straights. My point above was that it doesn’t take long for a new to racing paddler, wanting to eventually place well, will soon adopt use of a bent paddle in future races. Why?

If all in some odd race were required to use straight paddles only, of course there is little doubt that experienced race paddlers, top tier or middle pack paddlers, would still be the winners above the tourists who are not otherwise well experienced or have trained as race paddlers. i have never seen top finishers complete a race using anything other than a bent.

The reason new racers soon adopt a bent shaft is because that's what they're told to do and they are emulating what they see the top paddlers using. They don't want to look like a newbie that doesn't know what they're doing. They certainly aren't running time trial comparisons between bents and straights of various lengths and angles to see what actually works best for them and their paddle stroke.

What they should really be doing is emulating the way the top paddlers train. A bent shaft paddle won't make them a fast paddler but hard and focused training will. But it's a lot easier to drop $300 on a paddle then it is to actually do the training.

Then, after buying a bent shaft paddle that is 8" shorter and 12 ounces lighter than the wood straight paddle they were previously using they're convinced that the bent shaft is what made the difference, not the 8" less length and 12 fewer ounces.

I do not believe that study concluded that bents were 2.4% faster than straights but rather that there was a 2.4% increase in impulse power. This would translate into a less than a 1% increase in speed. This was also not an actual test or comparison. It may or may not transfer into real world paddling and it may or may not apply to all power outputs (is that 2.4% increase only near max power or does it also apply to a more relaxed pace?).

The one thing I took away from that study and trying to make sense of other studies is that it is a complicated and nuanced subject that has not been studied heavily or well.

Alan

 

[kahel]

What they should really be doing is emulating the way the top paddlers train. A bent shaft paddle won't make them a fast paddler but hard and focused training will. But it's a lot easier to drop $300 on a paddle then it is to actually do the training.

how right you are with that statement.

 

[gumpus]

I do not believe that study concluded that bents were 2.4% faster than straights but rather that there was a 2.4% increase in impulse power. This would translate into a less than a 1% increase in speed. This was also not an actual test or comparison. It may or may not transfer into real world paddling and it may or may not apply to all power outputs (is that 2.4% increase only near max power or does it also apply to a more relaxed pace?).

The one thing I took away from that study and trying to make sense of other studies is that it is a complicated and nuanced subject that has not been studied heavily or well.

Alan

Yes. Sean Burke created a theoretical model and the model has not been validated with test data so it could be fundamentally flawed; we don't know but we should be open-minded to better models. Even if we assume the model hasn't missed anything important it applies only to seated paddlers. The 2.4% benefit assumes that the blade drag does not change between a straight and bent so maybe it applies to a straight Zav vs a bent Zav...or maybe that assumption is flawed. There is no basis for comparing one brand of paddle to another.

My take is that if we make all the assumptions made by Sean Burke (body mechanics defined by one paddler, seated paddlers, blades with identical drag coefficients) then there may well be a 2.4% benefit (or more, or less). It would be nice to have a model that can assess other paddle design parameters like weight, dihedral, Cd, edge losses, tip sharpness, ...? I'd like a better understanding of how all paddle design parameters affect efficiency.

 

[memaquay]

In 30 years of taking high school kids on trips, I have experienced a particular situation several times. The well to do parents want to outfit their kids with top notch gear, so a trip to the canoe store was in order. I'm not sure who the salesperson was, but the kids invariably ended up with bent shafts. The other kids would look in awe at this marvelous bit of technology, and then the rich kid would start paddling, and 9 times out of 10, they would use the paddle with the wrong power face, so backwards or whatever you want to call it. Not wanting to embarrass them, I wouldn't correct them until I had a private moment, and quite a few times, they told me that I was wrong, lol, as they adjusted their new tilley hats and quick dry clothing. Meanwhile, the scuffers in jeans and t shirts with the arms ripped off were flailing away with their three pound aluminium and plastic paddles, leaving the Martha Stewart crowd in the dust. Of course, this in no way reflects my opinion of bent shafts, I'm just jawin on my observations.

 

[yknpdlr]

Although most of my students in 30 years have not been in the same upper class economic level, a few have shown up for BSA wilderness guide training with a bent and have had the same paddle orientation problem. Most all of the class are college age students with a desire to work at an Adirondack scout camp for the summer if they certiify. The others are stuck with using heavy old scout camp splintered wood paddles or mis-sized aluminum/plastic Mohawk paddles as they, like many other newbies, do their own fashion of single stroke hit and switch wag the Grumman canoe down the lake for the first day or so until they catch on with some basic correction stroke instruction able to hold a somewhat straighter track. Thankfully the old solid plastic paddles are long gone. For my canoe training portion, a couple of days earlier before and on the 5 day Lows Lake trek tripping field exercise, I will use one of my own straight wood paddles, solo or tandem with another instructor. Or I may often temporarily use a Mohawk paddle like theirs to demonstrate that even they too with a cheap paddle can learn to control a canoe with proper power and correction strokes. Some may later even get to try out one of my paddle types to experience the difference.

I recently joined an organizational instruction session sponsored by NYSDEC and The Nature Conservancy to learn how to ID and manage aquatic invasive species plant growth. The lead young lady instructor, during an on-water session in canoes, had a wood bent that she was using in "scoop" fashion. She thought she was quite correct until I respectfully demonstrated to her how I used mine, and why. To her credit, her specialty was knowing the name, including both the common and scientific name, of most every plant we encountered in the water. I can’t do that.

 

[Steve in Idaho]

In 30 years of taking high school kids on trips, I have experienced a particular situation several times. The well to do parents want to outfit their kids with top notch gear, so a trip to the canoe store was in order. I'm not sure who the salesperson was, but the kids invariably ended up with bent shafts. The other kids would look in awe at this marvelous bit of technology, and then the rich kid would start paddling, and 9 times out of 10, they would use the paddle with the wrong power face, so backwards or whatever you want to call it. Not wanting to embarrass them, I wouldn't correct them until I had a private moment, and quite a few times, they told me that I was wrong, lol, as they adjusted their new tilley hats and quick dry clothing. Meanwhile, the scuffers in jeans and t shirts with the arms ripped off were flailing away with their three pound aluminium and plastic paddles, leaving the Martha Stewart crowd in the dust. Of course, this in no way reflects my opinion of bent shafts, I'm just jawin on my observations.

I see this a lot. Mostly with those just starting out with SUP, which is really popular around here - for good reason. (We do a lot of mixed groups on the local water) I tell them, "think broom, not hoe". It usually sinks in pretty quick.

 

[ABT]

Well, since we’re talking about folks using the bent shaft paddle incorrectly, I’ll throw out there that my father to this day, knowing full well how a bent shaft is supposed to be used, still says he prefers to use it the wrong way. To hear him tell it, he prefers the stronger “catch” phase he gets with this method, despite the extra losses from “lifting” water in the later portion of the stroke. I imagine there is some benefit to the catch the way he does it, but the rest may be more ingrained stubbornness on his part than anything.

He now uses primarily a straight shaft paddle, but for my entire childhood, Dad used a Mohawk bent shaft paddle. I guess they were not as common around here as other places because I had never seen another like it in person until fairly recently. As a kid, I always thought it was so cool that he had this gloss black and aluminum paddle, when all you ever saw on the river were old beat up clunky wooden outfitter specials that were half paddle, half club. He had acquired it years before I was born, on a canoe trip where he had broken his wooden paddle and didn’t have a spare. They limped their tandem along until they came to the confluence of the Jacks Fork and Current Rivers, aptly named Two Rivers Landing. There is a sole outfitter there, and they have a general store that overlooks the confluence from up on the hill. The original log cabin style store was destroyed in a bad flood a few years ago, and they have a new one in its place although it’s not as rustic looking. Lot of good memories stopping in at that old store. Anyway, on that day they had one single paddle in stock for sale and it was this odd looking one with a bent shaft. He thought it looked to be well made, and might offer some additional leverage, and besides that he had no other options if he wanted to continue his trip, so he bought it. He used it for several decades as his only paddle, and only once came close to losing it - the evening of the first overnight river trip we ever took when right at dusk pulling into a gravel bar we hit a rock and submarined the old 17’ aluminum barge and all of our gear. Also known as the “Night of The 100 Raccoons”, but that’s another story. All of his paddling was self taught, and while he has since learned a proper J stroke, it was many, many years he used that bent shaft backwards using a sort of goon stroke/rudder for correction. When using the “backwards bent” and a goon stroke, the paddle naturally falls into a pretty decent rudder position, and it’s actually fairly easy to steer either direction from one side in the back of a tandem, which is about all the positive that can be said of it. But it worked well enough, and we had some great times in that old aluminum tandem never knowing any better. I still paddle with him a lot, both in solos now and much better than we used to be, and all of our gear is now stored in my shop. While it doesn’t get used much anymore, that old Mohawk bent shaft is hanging right there with some beautiful wood and carbon pieces of art, but used forwards or backwards it’s the last paddle I’d ever let go of.

 

[Glenn MacGrady]

I would think that a bent shaft paddle increases speed by at least 2.4% compared to a typical straight tripping paddle. Burke took input data from Caplan, who, as I understand it, modeled an outrigger canoe paddler who used the same paddle differing only in blade angle from 0° (straight) to higher angles.

Here is the entire full text of the 2009 Caplan study, which concluded:

". . . the fastest boat velocity was achieved by ensuring that the face of the paddle was vertical at the point in the stroke when the paddler had accelerated the paddle to the greatest extent through the water." (Emphasis added.)

https://www.poseidonsalbtraum.de/infos/The_Influence_of_Paddle_Orientation_on_Boat_Velocity_in_Canoeing.pdf

Burke's later study concluded that "you'll go faster with a bent shaft" and that "the optimum bend angle . . . was 12 degrees." I see no reason why this shouldn't hold true for top tier racers, mid tier racers, low tier racers, wilderness tourers, or slow-pokey old men. Whether any given paddler cares about this is a subjective, psychological issue not relevant to the objective physics that this topic was primarily intended to investigate.

It is also an objectively empirical fact, rather than just random subjective preferences or mass lemming-ness, that just about every serious flatwater and outrigger racer for the past 50 years has chosen to use bent shaft paddles. In all fields, racers are always at the cutting edge of what equipment, techniques and body mechanics make them go the fastest.

In addition, there is lots of anecdotal evidence that one uses different body mechanics with bent shafts than straight shafts. The power is applied more with a torso crunch push-down of the paddle than with an arm-shoulder push-pull. Because of this difference in body mechanics, many paddlers feel that, when paddling long distances, bents are more ergonomically efficient because they are easier on the shoulders, arms and wrists than straight paddles. However, I'm not currently aware of any scientific studies of these anecdotal claims.