WiTHiN Lake Test!

The lake test was fairly successful, but our speeds were about 10% slower than predicted.

Our 150 watt predicted speed was 10.2 kph and I measured 9.2 kph. That's only a 10% decrease, but it required 50% more power to reach 10.2 kph than expected which is quite a bit. Here are the speed test results:

100 watts = 7.8 kph

150 watts = 9.1 kph

200 watts = 10 kph

250 watts = 10.3 kph

all packed up and ready to go

150 watts over 24 hours will net out to about 110 average watts (using SRM data from my two 24 hour HPV events). 110 watts is about 8 kph average speed. 8 km * 24 hours = 192 km which is 24 km over the current 168 km record. This is OK, and for what we are trying to accomplish with the 24 hour record event as an introduction to the Atlantic expedition, it is acceptable.

My friend Bryon Howard was my support boat for today

Rick is concerned and thinks we can narrow down where some of the losses are coming from. Starting with a new prop that Rick kindly made for me and is en route from Melbourne now. Some other refinements include cleaning up some underwater fairing issues and more tests. Another reason for the slower than expected speeds could be due to some incorrect hull shape information. It appears that there is more displacement than we originally calculated. I suspected this, as the Hyak kayak hull that we used for WiTHiN is a lot more stable than we expected. That stability comes at a cost - great for the ocean boat, but so quite as good for a 24 hour record attempt.

I am assembling the rudder. Note the drive leg and gear on the dock

Test ride thoughts: It was PLENTY of fun! I was pretty thrilled about it all. We spent a couple of hours tooling around the lake. It felt exactly the same as my M5. During M5 training rides, I focus on extended periods of non-stop pedaling on flat terrain, so that aspect of pedaling the boat felt pretty typical.

Bryon Howard

To not have to deal with traffic, noise, beeping cars, etc was a joy. I far preferred being on the water, but I think mostly because it is something new to me. I would much rather be there than on my road bike now, but getting WiTHiN to the lake is a bit of a pain. However, I appreciate how much easier this is than what I went through preparing Critical Power for the 24 hour record! Finding a closed track to do tests on was VERY difficult. Also, we could not test on anything other than almost windless days. Added to that, the fact that I always required help meant that we were able to test CP only a few times! This was VERY frustrating.

Loading WiTHiN on my car and driving out to Glenmore Reservoir by myself won't be difficult. I can see that weather won't be a huge concern either.

Rudi - my dad is an integral part of my team

Ben Eadie - camera man

We instantly drew a crowd. I met two families who were with kids that went to schools that I had visited for KidPower presentations. Kayakers were all generally stunned that a pedal boat could be faster than a kayak. I let Bryon Howard, my kayak instructor friend take it for a spin and he was thrilled at how comfortable and fast it was. Bryon and I compared our effort levels at various speeds. My long distance cruising intensity of 150 watts speed was equal to his 20 minute all-out effort pace.

I am in the process of getting some decals made up with the WiTHiN and the PedalTheOcean URL on it. The more often I am out and visible, the more buzz I will generate. This is my biggest reason for mounting the 24 hour HPB record event.

I am concerned about the speed, of course, but if it is due mostly to the hull shape, then there is not much we can do about it. That's OK - it is still fast enough for a new record, but I will have my work cut out for me. There are other issues that I need to balance with finding the speed – making sure WiTHiN looks great – that's hugely important. People have to instantly recognize that she is something new and unique. WiTHiN has to invite curiosity and has to look sexy in her newspaper and magazine spreads.

WiTHiN compared to a tandem and single kayak

Launching WiTHiN is a one-man job

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5 Responses to “WiTHiN Lake Test!”

  1. # Anonymous Anonymous

    Congratulations! Now I'm motivated to get back on building my 50th birthday/50 mph streamliner.

    Just picked up a pair of Pyro platforms today. I'll put the cleats on tomorrow to try them out.

    Nick Hein

  2. # Anonymous Anonymous

    Just one more quick comment. After looking at the videos I noticed alot of stuff haning out in the breeze. If you could put on a windshield and maybe a lycra canoe skirt to cover up the draggy stuff with a fairing you'll get more speed.

    I calculated that for every square foot of drag you remove you'll save yourself 2 watts.


  3. # Anonymous Anonymous


    Nice test ride! I was excited myself to see that it worked good on the lake. My main concern was the stability on windy and open water conditions.

    About the speed you were talking about, when i saw the comparison of the withing and the other kayaks i realized that maybe increasing the water line legth of withing could give you more speed. On sailboats, the bigger the water line leght, the faster a boat can sail... i don't know the principles for all that, but could be an alternative for a future project.


  4. # Blogger Jason

    Hey Greg

    Really good to see such solid progress.

    Regarding the speed and relating to the increased displacement ... the displacement is going to be equal to the weight of the boat. Lighten it, you'll go faster. The perfect weight for a boat is zero!


  5. # Anonymous Anonymous

    Just a few more comments after a good night's sleep. If your prop is designed with Prof. Larribee's "Minimum Induced Loss" method, and optimized for your specific record conditions it's quite possible you'll get back the power you're looking for.

    I saw a comment about hull length affecting speed. The principle involved there is that the MAXIMUM speed is determined by the hull length, because the hull will be one (half)wavelength long at its maximum speed. Check the "hull speed", but if it's higher than your intended record speed don't do anything different.

    The mitigating effect is from skin friction.

    Should do anything you can to reduce wetted area (not really possible for the current record attempt) and wind resistance (with fairings and attention to detail. Also wax the hull really well if you haven't already to reduce water skin friction. There may also be specialty surface treatments that will help.

    Nick Hein  

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