SweetZpot-OarZpot

[Berend]

Does anyone have experience with the OarZpot sensor from the company SweetZpot, https://rowing.sweetzpot.com/ to measure the force/power on the oar?

I can see how such a sensor would measure the force, but I am unsure how such a sensor would measure displacement. Without the displacement, I do not see how you would calculate the Power or Work done, although they state that the app does calculate the Power. Does anyone know how this works, or even better, has experience with this device?

Thanks, Berend.

[Remomex]

I actually rowed with the founder of the company at Masters Worlds in Bled last year and spoke to him about it (he tried to sell me on it). The sensor supposedly measures the minute bend in the shaft of the oar as you apply force during the drive, which it uses to generate your power/work done as well as a power curve. I can't speak to the efficacy of the device and I know that it was fairly new when I saw it in Bled, but it sounds interesting.

[sandor]

Wouldn’t that require calibration of individuals oars?

[eeoyre]

Sounds like SmartOar, but without having to permanently modify the oars. Would be interesting if someone compared its accuracy with that of the NK Empower oarlock.

[Berend]

Thanks for the replies. I can see how you can measure the force - by applying a strain gauge and then calibrating it. I presume this could be quite accurate. However, I cannot see how you could determine the power. For the power, you need to have displacement (how much the blade travels through the water) as well. With the Empower oarlock, the rotation of the gate is measured to determine the displacement. I don't see such a simple solution with a sensor attached to the oar itself.

[eeoyre]

I think some sort of accelerometer should do the trick, you can detect changes of direction, duration of travel, and speed and figure out the displacement from that. To me, that seems like an easier problem to solve than accurate force measurement.

[Stelph]

I have one tho I haven’t had much time to actually test it thoroughly, the first time I did I couldn’t get it to show up correctly on the iPhone app but apparently the android app is more stable

It’s an interesting concept not completely dissimilar to weba’s Power oar in that its easily attached and measures the oar bend and stroke length using an accelerometer, but it’s considerabky smaller and the app has a UI that’s miles ahead

http://www.weba-sport.com/en/products/o ... r-meter-en

As already mentioned it’s also similar to smartoar but has the benefit of being able to use a smartphone as a live screen rather than needing a multi thousand dollar device which was always smartoars major drawback and I think stopped it really taking off.

The downside to the sweetzpot currently is that the power curve is relative rather than absolute, by that I mean it can draw a curve but not give absolute power numbers because you can’t calibrate the sensor to the oar bend yet like you can for the Weba - they’d gone very quiet recently on updates but I think they’re focusing on the rowing sensor again, apparently brining a calibration mode in so you’ll get absolute power

I think NK is still the market leader by a good margin but the sweetzpot has a chance to better it if they can get it to show absolute power readings accurately and bring in support for multiple sensors at the same time for scullers/crew boats I think itlll be a good buy considering it’ll cost a huge amount less than NK and suffer less wear/you can use whatever gates you want

[eeoyre]

Oh, for some reason I didn't realize they didn't measure absolute power numbers. Then no comparison, the empower oarlock is much more useful. Thanks for clarifying that! Definitely a ton of potential if they can figure that bit out.

[Berend]

Thanks for the clarifications.

I think that an accelerometer in the device will not measure the displacement which is required accurately. One reason is that the accelerometer will give the "aboslute" acceleration - not the acceleration relative to the footplate. It is the displacement relative to the footplate/boat which should be determined.