Bent vs. straight paddle - direct comparison plus bonus footage

[Cruiser]

Allan, thank you for taking the time to put some numbers on the paddle discussion, there are lots of folks sharing paddle experience and favourite type/length etc and shows we all have some interest.

I am really enjoying this discussion, but I have a few things that sort of give me pause for thinking.

Paddles are generally built to a set of specifications, when you buy a paddle you look for specifications that meet your use criteria. Initially, most sizing methods are trying to determine the shaft length and then blade area/shape .... that works for the specific user.

When you use the paddle length, as a paddle descriptor, personally, I feel it tends to confuse the issue IMO. As an example ... when I say I went from my 62" BeaverTail to a 55" Sugar Islet Bent Shaft and it was more comfortable and I found it easier to paddle with less fatigue. While it is a true statement, it really doesn't give the reader any information about the mechanics associated with your opinion.

The reality is that both paddles have a 32" shaft (which is my sizing) , so overall length difference is in the blade(s) not the shaft, the Beavertail has an area of 148 sq. inches versus 124 in the Islet, that is a significant difference in the water being pushed around . The statement is basically true to how I feel about these two , if I was using my solo. The seat is quite low and the longer length of the BT makes clearing the stroke more difficult, the shorter blade, in this situation, makes it easier to lift the paddle clear of the water ... making the Islet an easier stroke. The BT is moving a lot more water with each stroke so cadence comes into play as well, if you try and keep the same stroke rate with these 2 paddles the observation is quite predictable.

Swapping the above to the Otter Tail gives pretty much the same result, it is 62" with a 32" shaft and 124 square inch blade, meaning it pushes the same water as the Islet, but that long blade doesn't work as well in the lower seating position.

This is a long winded way of saying that with out the additional information included in a post, there is little way for the reader to learn from the posters experience, because the pertinent info isn't included.

Allan, I think using the BPM as a governor is a decent attempt at keeping it a level playing field. I was looking at the photos and that straight shaft does look to be some larger than the other 2, any chance you could overlap the blades and see if that is correct or an optical illusion?

Brian

 

[Alan Gage]

When you use the paddle length, as a paddle descriptor, personally, I feel it tends to confuse the issue IMO. As an example ... when I say I went from my 62" BeaverTail to a 55" Sugar Islet Bent Shaft and it was more comfortable and I found it easier to paddle with less fatigue. While it is a true statement, it really doesn't give the reader any information about the mechanics associated with your opinion.

That is a good point. My entire canoe paddling career I've been using ZRE paddles and the couple paddles I've had that weren't ZRE were very similar blade shapes/lengths so I've always gone by total length in inches. I'll measure the shaft lengths and post them when I get a chance.

I was looking at the photos and that straight shaft does look to be some larger than the other 2, any chance you could overlap the blades and see if that is correct or an optical illusion?

I'll measure this as well. The white/green straight blade is definitely larger as I built it as a whitewater paddle. The carbon straight is possibly wider than the bent. It's a ZRE recreational paddle and I believe they're usually wider than the racing paddles. Also, the bent has probably had at least 1/2" worn off the tip over the years.

Alan

 

[Steve in Idaho]

Sometimes I take more than two paddles. None is primary or secondary or tertiary; they are all used for different situations or merely because variety is the spice of life. And the next trip I may take two or three different paddles. That's the purpose of having a harem . . . of paddles and canoes.

My grandson asked just the other day, "how many paddles do you have, Papa?"

" Not as many as I'd like."
He hasn't seen all the canoes yet.

 

[gumpus]

My grandson asked just the other day, "how many paddles do you have, Papa?"

" Not as many as I'd like."
He hasn't seen all the canoes yet.

This is probably the single biggest reason that I have not developed fondness for DB paddles. I do not want to own dozens of DB paddles and "try everything" like Idiot Savant just to find the one that I may like and use. I'd guess that at least 80% of my canoe paddles mostly just gather dust (although in many cases that's fine and they are not for sale).

 

[Glenn MacGrady]

In any event, my interpretation is that regardless of stroke rate—whether a racing, tripping or other recreational stroke rate—every stroke with a bent shaft paddle will have greater forward propulsive velocity than a straight shaft paddle applied with the same force, because the bent shaft blade is more vertical to the water than the straight shaft paddle when they are at their respective points of maximum velocity.

Maybe. I think it's important to remember the assumptions behind Sean's analysis. His model is based on the stroke mechanics of one elite outrigger paddler and he points out that it's a big assumption. The 12 degree angle is optimal for that one paddler.

Maybe?

While it's true that Dr. Burke's research on the amount of propulsive force gain attributable to a bent shaft paddle over a straight shaft paddle relied on assumptions made from video studies and mathematical modeling of one outrigger paddler, there's no doubt that there is some amount of propulsive force gain. This is proven by the empirical results of the last 50 years of flatwater and outrigger racing, about which it's probably accurate to observe that every such racer uses a bent shaft paddle.

There is no question that bent shafts are maximally faster than straight shafts because they produce more propulsive force per stroke. The only objective questions are how much faster are they and, relatedly, what is the optimal bend angle. My sense is that flatwater racers have used bend angles that have gone from 15° to a now fairly standard 12°, while outrigger paddlers have flirted with 11° and 10°.

Outrigger racers, who on ocean waves do a lot more ruddering and bracing than flatwater racers, have also increasingly adopted double bend paddles. I'd like to see research on propulsive force per stroke between single and double bend paddles. The double bend can be ergonomically easier on the shaft wrist—less bending of it required—but it's not clear to me that they have a speed advantage over single bends.

Of course, there is also the subjective question as to whether any of these objective force and speed facts (whatever their quantities) matter for the tripping or recreational canoeist. That's for each individual to decide. Nevertheless, I appreciate and am interested in the efforts and discussions to tease out whatever empirical science there may be.

 

[stripperguy]

I too continue to enjoy these discussions.
I have noticed that although paddle velocity and angle have been talked about, there seems to be no mention of the vertical component of the paddle forces.
A straight blade paddle pulls the hull DOWN into the water with the rear half of every stroke.
Proper technique with a bent shaft does not.
While I’ve never instrumented a hull and paddle simultaneously, I would suspect that disparity in the vertical plane would account for most of the paddle efficiency difference.
With that straight shaft, it’s almost like you’re adding a 50 lb load with half of every stroke!

 

[Alan Gage]

A straight blade paddle pulls the hull DOWN into the water with the rear half of every stroke.
Proper technique with a bent shaft does not.
While I’ve never instrumented a hull and paddle simultaneously, I would suspect that disparity in the vertical plane would account for most of the paddle efficiency difference.
With that straight shaft, it’s almost like you’re adding a 50 lb load with half of every stroke!

I tend to think the "lifting water" theory is a bit too simplified. I seem to remember reading something by Jonathan Winters once where he said there really wasn't much to it. But of course I don't have enough knowledge to actually make a case for it one way or the other.

I think we've all seen newbie paddlers who pour on the power the whole way through a very long stroke and I think in that case it might have some merit. But skilled paddlers are generally putting most of the force into the beginning of the stroke with the power phase ending near the hip if not sooner.

I ordered a new Zav straight paddle last week and am waiting for it to arrive. The one I currently have is an awkward length at 53" so I think I'll cut it down to around 50" and see how it compares directly to a bent of the same length. From what I saw running this test last week I don't think it will make a difference. I'll leave the new one around 57" for a lightweight straight, which I don't have.

Alan

 

[Glenn MacGrady]

I ordered a new Zav straight paddle last week and am waiting for it to arrive.

What blade, Alan? I assume an asymmetrical grip.

 

[Alan Gage]

What blade, Alan? I assume an asymmetrical grip.

Standard blade shape in the recreational layup. A little heavier, a little cheaper, and, if I remember correctly, a little more robust due to some fiberglass in the layup. Yes, asymmetrical grip. If I feel ambitious I might make a wood grip for it.

Alan

 

[Alan Gage]

I was looking at the photos and that straight shaft does look to be some larger than the other 2, any chance you could overlap the blades and see if that is correct or an optical illusion?

I measured the blade width the other day. The bent was 8.25" wide and the carbon straight was 8.5" wide. Both being Zavs the blade shape is pretty much identical. The 2nd straight with the white/green blade was 8.75" wide.

I think it's mostly an optical illusion in the picture because of the angled blade on the bent shaft.

Alan

 

[lowangle al]

I too continue to enjoy these discussions.
I have noticed that although paddle velocity and angle have been talked about, there seems to be no mention of the vertical component of the paddle forces.
A straight blade paddle pulls the hull DOWN into the water with the rear half of every stroke.
Proper technique with a bent shaft does not.
While I’ve never instrumented a hull and paddle simultaneously, I would suspect that disparity in the vertical plane would account for most of the paddle efficiency difference.
With that straight shaft, it’s almost like you’re adding a 50 lb load with half of every stroke!

I think with proper technique you can eliminate that upward pressure on the recovery with a straight shaft too. When I do "hit and switch" I try to stop my stroke as soon as the power phase is complete. For the recovery I pull the paddle forward and up trying to minimize any resistance from the water, this also sets me up for my next stroke. When I'm using correction strokes I use that upward pressure to make the correction. My "J" stroke is done with the paddle being closer to horizontal then having the thumb on my upper hand go way down and the paddle being more vertical. I also get that J shape at the end of the stroke while bringing the paddle forward to add to the correction.

You may be right about a bent shaft not having that upward pressure, I'll have to take your word on that. But you're still going to loose some forward power during the correction. Unless you do "hit and switch"

 

[DougK]

there's no doubt that there is some amount of propulsive force gain. This is proven by the empirical results of the last 50 years of flatwater and outrigger racing, about which it's probably accurate to observe that every such racer uses a bent shaft paddle.

but, have they ever tested it ?
;-)
there's a lot of superstition in all racers, and unwillingness to change from tradition..
I follow an Olympic flatwater sprint racer on instagram and he uses a straight paddle..



that boat must be pretty quick, holding 5mph in my Wenonah Vagabond 14.5' solo takes me well over 120bpm..

 

[tketcham]

I follow an Olympic flatwater sprint racer on instagram and he uses a straight paddle.

I'm not a flat water Olympic paddler but the high-kneel position in a needle boat doesn't seem comparable to a typical solo recreational cruising canoe, which I do paddle. I've tried straight blades for cruising but always come back to a bent blade paddle for putting in the miles. That's me anyway, not based on science; my opinion is as anecdotal as you'll find. :~)

 

[lowangle al]

but, have they ever tested it ?
;-)
there's a lot of superstition in all racers, and unwillingness to change from tradition..
I follow an Olympic flatwater sprint racer on instagram and he uses a straight paddle..

View attachment 148528

that boat must be pretty quick, holding 5mph in my Wenonah Vagabond 14.5' solo takes me well over 120bpm..

What I find interesting is that it appears that the straight shaft paddle is the paddle of choice for sprint racers. Why is this the case when most other types of canoe racers use a bent? It is not universal that a bent shaft is faster.

 

[Glenn MacGrady]

I follow an Olympic flatwater sprint racer on instagram and he uses a straight paddle..

Olympic high kneel sprint canoeing uses different body mechanics and the races are only 200, 500 and 1000 meters long. The body mechanics have always favored long, straight paddles as far as I know. But no one paddles that way, or in those boats, or for those short a distances except for Olympic sprint canoeists. It's not comparable to recreational canoeing or marathon or outrigger canoe racing.

Lots of trippers and recreational canoeists prefer straight paddles to bents even though they may be convinced that bents are slightly more efficient. So do I sometimes. This past weekend I paddled two days solely with my new-to-me Pat Moore "cue" paddle and ignored my favorite bent ZRE. The Moore cue is an excellent carbon straight paddle and might even be perfect if it were 13 oz. instead of 19 oz. and was an inch shorter and slightly smaller bladed (for my ever evolving tastes).

 

[lowangle al]

I understand there are different body mechanics and different type boats, but it's still a paddle pushing a boat through the water. I thought maybe it was the height of the paddler above the water. The sprint racers have that high kneel, which would make a difference in the angle the paddle enters the water. It also affects how deep your stroke can go without submerging your lower hand. I know I can't do my most efficient stroke from a seat lower than about 11 inches without getting a hand wet. This doesn't explain why they use bents racing outriggers. They have very high seats. This includes outrigger sprint races that are similar distances to the olympic style sprints. Are there any other types of canoe racing where straight shafts dominate?

 

[gumpus]

Maybe?

While it's true that Dr. Burke's research on the amount of propulsive force gain attributable to a bent shaft paddle over a straight shaft paddle relied on assumptions made from video studies and mathematical modeling of one outrigger paddler, there's no doubt that there is some amount of propulsive force gain. This is proven by the empirical results of the last 50 years of flatwater and outrigger racing, about which it's probably accurate to observe that every such racer uses a bent shaft paddle.

There is no question that bent shafts are maximally faster than straight shafts because they produce more propulsive force per stroke. The only objective questions are how much faster are they and, relatedly, what is the optimal bend angle.

Sorry, missed this post. My point is that we simply do not know the inference space associated with Burke's conclusion of a 2.4% benefit. We don't know the effect of seating position or paddler height or normal paddling styles vs the one elite paddler studied or or or. I consider Burke's analysis a (valuable) "stake in the ground".

As far as other relevant parameters I have many curiosities beyond blade angle. The biggest one that jumps out at me from Burke's study is blade drag coefficient. If straight vs 12 degree has only a 2.4% theoretical benefit I'd like to know how much drag coefficients vary since that MIGHT be a bigger effect! I'd also like to understand the effect of shaft stiffness.

 

[Alan Gage]

Are there any other types of canoe racing where straight shafts dominate?

Dragon boat paddles are straight blade as well.

 

[yknpdlr]

While in Canberra on a business trip, after a brief chat about my recent Yukon 1000 mile race, I was invited by the Australian National Dragon Boat Team head coach to take an unocupied seat during a traning session. Yes, straight blade wood paddles. Very command driven specific action orders are given by the coxswain on board during the relatively short (2000 meter) hard paddling sprints.