Faster is slower and slower is faster

[PonoBill]

I made this point in a recent post in the "Getting pretty good..." thread:

When people get serious about instrumenting SUP boards to try to make them go faster, I expect there will be a cadence for every board/body/speed that has something to do with that kick and a lot to do with limiting blade slip and getting the most energy into forward motion. Blade slip is wasted energy, and generally paddling faster than the board is going guarantees excessive slip. It's a factor other paddlesports watch closely and SUP racers don't watch at all, but there's a strong likelihood that SUP racers will go faster when they paddle slower.

I wonder if anyone is playing around with this. I've been saying that cadence is personal for years, and now I'm thinking I was full of crap. I think cadence needs to be matched to board speed. I think your paddle size and the power you put into the front of the stroke is how you get the right cadence for the speed you currently attain. I'm starting to think that one reason Devin Blish is fast is because she's matching paddle size to her board speed.  I'm not sure about this, SUPs are very light compared to vessels like a six man canoe, which weighs about 1260 pounds with crew (assume 160 pounds per crewperson and a standard 300 pound OC6). With that weight, paddling more than a tiny bit faster than the canoe is going is a pure waste of energy. Deceleration between strokes happens in an OC6, but at any reasonable stroke rate it's small and it's made up for by the glide that happens when the power of everyone's stroke hits at the exact same time and just a little faster than the boat is going. You never feel that glide if you're thrashing ten strokes per minute faster than the boat is going.

But there's clearly some benefit in keeping a SUP board from decelerating too much. Maybe at the pointy end of the pro paddler group that benefit overcomes any thought of efficiency. But back in the middle of the pack, and in the open group that runs far behind it, there might be efficiencies that translate into speed.

Vaaka makes a cadence sensor that might be worth playing with, but I wonder why cadence sensing requires a device on the paddle. Each stroke accelerates the board. The pulses should be easy to detect with an accelerometer. In fact I could see them on the Paddle Pod I built long ago, but I treated them as noise. I sensed the start of each stroke with GPS data but used an accelerometer to show the difference in paddle speed and I used a dragged impeller prop to sense board speed independant of current.  I notice that the NK speedcoach shows paddle cadence, I assume this is what they are doing. I've ordered one to check it out.

It'd be nice if the Makai showed paddle cadence. I don't know what kind of room they have in the case and on their board but a signal-conditioned three-axis accelerometer to enable cadence count is one tenth the size of a pencil eraser (4 x 4 x 1.45mm), and other than a little bit of supporting electronics the changes would be 99 percent in software.

I need to ping Larry Cain about this, it's his stroke rate that got me thinking about it. Well, that and paddling OC6 2-3 times a week. You out there Larry?

[baddog]

I wonder why cadence sensing requires a device on the paddle(?)  The pulses should be easy to detect with an accelerometer.

It doesn't and it is.  The built in accelerometer in my Garmin Vivoactive watch works perfect, although you need to divide the cadence by 2.  The activity tracking is second to none and the variety of data fields available is amazing.  The new Vivoactive HR has a built in paddle app which counts stokes.  And all the top end Garmin watches work the same way.

Besides the great activity tracking, the Vivoactives are way better smart watches then the Apple watch.  Waterproof, built in GPS and long battery life (10hrs on GPS, 2 weeks without) make it the easy choice for anyone except Hipsters and MeGees.

[TallDude]

Last night I was doing loops in the harbor on my unlimited. It was blowing close to 20 mph, so great DW in the outer channel, but a serious grind coming back up the inner channel. Candice had her training group doing sprints into the wind. I caught up to them and sprinted with them. I passed most of them except for Dave Boehne and another guy (Candice was hanging back coaching). I noticed that my stoke was almost 1 to their 2. Maybe because of my height and how deep I drive the blade when going into the wind made the difference. My unlimited maintains momentum due to a number of factors, so that really helps into the wind as well.

[zachhandler]

I have noticed a long slow deep stroke upwind is faster. I think minimizing the amount if time the blade is in the air has something to do with it. The blade is only 90in2, but is is getting whipped forward and therefore experiencing a much higher relative wind speed. Also the bent pody position during the pull phase is more aerodynamic than the more upright return.

[JP4]

I wonder why cadence sensing requires a device on the paddle(?)  The pulses should be easy to detect with an accelerometer.

It doesn't and it is.  The built in accelerometer in my Garmin Vivoactive watch works perfect, although you need to divide the cadence by 2.  The activity tracking is second to none and the variety of data fields available is amazing.  The new Vivoactive HR has a built in paddle app which counts stokes.  And all the top end Garmin watches work the same way.

Besides the great activity tracking, the Vivoactives are way better smart watches then the Apple watch.  Waterproof, built in GPS and long battery life (10hrs on GPS, 2 weeks without) make it the easy choice for anyone except Hipsters and MeGees.

I just got a Vivioactive HR a couple weeks ago. Though I haven't tried the SUP function yet, my buddy Tre has on a recent downwinder, and the stroke counter seems to work well. The GPS tracking is really good and it acquires satellites almost instantly. The wrist based HR monitor is very accurate. It also has a sleep tracking function that is pretty interesting, if not entirely accurate. A week of battery life and functions independent of the phone. Amazing piece of kit for $250.
JP

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[Luc Benac]

It'd be nice if the Makai showed paddle cadence. I don't know what kind of room they have in the case and on their board but a signal-conditioned three-axis accelerometer to enable cadence count is one tenth the size of a pencil eraser (4 x 4 x 1.45mm), and other than a little bit of supporting electronics the changes would be 99 percent in software.

If the Makai could be retrofitted to show cadence and record speed for download to a computer, coupled with the streamlined shape, it would be the one and only tool for the job.

[mrbig]

+1 on the Garmin Vivioactive HR. My first gadget mostly for strapless HR info, GPS works well, and it works fine as a standalone although rumor has it there is a windows (hahaha) phone app. We will see bout that..

[PonoBill]

You guys talked me into it, I order one. Expensive day. I also bought 400 18650 batteries and a spot welder for an EV project I'm working on.

[JP4]

+1 on the Garmin Vivioactive HR. My first gadget mostly for strapless HR info, GPS works well, and it works fine as a standalone although rumor has it there is a windows (hahaha) phone app. We will see bout that..

I don't know how the Windows app will be, but so far I've found the Android Garmin Connect app to work really well. The only down side to the whole thing is I can't read much on the watch without reading glasses. Doh, getting old! I just read all the data off the phone app.
JP

[coldsup]

You guys talked me into it, I order one. Expensive day. I also bought 400 18650 batteries and a spot welder for an EV project I'm working on.

Pono....I am starting to think you are a millionaire with all your houses with stunning gardens, bikes, cars and gadgets.

[PonoBill]

I've done well, but nothing extraordinary. Owned a very sucessful business. Now I'm a retired guy. Most of the stuff I have is from when the money was rolling in, now it's rolling out. I watch my bucks like every retiree.  I sold three of the bike motors I had to a guy in Oahu, so I'm feeling flush. Spent that on the stuff I bought today. Paypal money--a little too painless when you spend it.

[SUPJorge]

We need a paddle-based strain gauge to measure power applied to the paddle and a signal-conditioned 3-axis accelerometer to identify cadence and paddle positioning, both linked to a GPS for speed and a heart rate monitor.

I've been looking at wrist based HR meters for a long time, bought and retuned two of them, had a friend buy and return the Garmin Phoenix and have been waiting for the Vivosmart HR since February. Unfortunately, the reviews of the accuracy of the heart-rate tracking have been less than glowing, and that's with your hands fixed on a bike handlebar. http://www.dcrainmaker.com/2016/01/garmin-vivosmarthr-review.html The wrist-based technology is just not there yet. Need to wear the chest strap if you want accurate heart rate.

[PonoBill]

Might be hard to calibrate. I tried adding a strain guage to the paddle pod, but didn't get far. Problem is that a strain guage needs to be well anchored at both ends to the flexing surface, which is why the paddle guages currently available have a modified shaft. PIA. You could derive force from the weight and the acceleration (F=ma) though there's a friction component hidden there that's harder to judge. It could be compensated by the deceleration but microbumps, or real bumps all play a part too. The trick would be to gather data with a more direct measurement for a lot of boards and a lot of people in a lot of circumstances and come up with factors that relate to speed, weight, acceleration and deceleration that give a good indication of force. Yuck.

Anyway, worth thinking more about rather than just slinging stuff off the top of my head.

The specs for the vivoactive are remarkable. Can't help thinking that this is what Apple should have built. What's the point of a watch that isn't waterproof? I knew any watch that wasn't waterproof was useless when I was ten. Still, a generalized supercomputer in your pocket and a super powerful navigation system, interface, set of sensors, and computer on your wrist. We went screaming past the Dick Tracy science fiction stage long ago without even knowing it. Anyone that thinks AI isn't going to happen is delusional.

[blueplanetsurf]

I'm not sure if this has been posted here already but Johnny Puakea makes the same point about matching the stoke speed to the hull speed and has some really good technique tips in this video, here are some quotes:

"Most people try and get the stroke rate up instead of have the speed of the craft go up and then the stroke rate match it. So, that's to me the first mistake people make. And a lot of people would try to increase the stroke rate in the water instead of just getting rid of the airtime to increase the stroke rate."

"Patience in the water is one of the main things you want to learn. Load the blade. Lots of pressure. And be patient."

[blueplanetsurf]

sorry, duplicate post