Rick how did the hobie ti s do?
Nick b
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-------- Original message --------
From: "Rick Willoughby rickwill@bigpond.net.au [harryproa]" <harryproa@yahoogroups.com.au>
Date: 06-26-2015 9:33 PM (GMT-05:00)
To: harryproa@yahoogroups.com.au
Subject: [harryproa] HP Cruiser 60 Pedal Power
I have done some analysis of pedal power for a HP Cruiser 60 displacing 2000kg on each hull.
I have attached the Michlet drag curve (hope it displays). The black line is a power series fit of the Michlet output in pink. The equation for best fit is:
Drag (N) = 46.408 x Speed (m/s) ^ 1.9618
The departure at the top from the squared relationship is most likely due to hull interaction. It is not related to any dynamic lift because Michlet only works for displacement mode. In any case displacement mode is all that matters with pedal power unless you get a whole team:
https://www.dropbox.com/s/0rbvex2mwykjn4w/4XVideo.MOV?dl=0
Two pedalers working at 300W combined could get 3.1kts in calm conditions with smooth hulls. This is based on spinning two 17X18 props with 4X gearing:
http://www.apcprop.com/product_p/lp17018.htm
The propeller efficiency is 70%.
The gearing could be achieved with two Mitrpak boxes similar to those used on Peccadillo. The top box is T-122-M:
http://lampin.com/p/mitrpak-t-122-m-right-angle-gearbox-135876/
The submerged box is an R-102:
http://lampin.com/p/mitrpak-r-102-c2-m-right-angle-gearbox-135890/
That combination gives the 4X speed increase.
With one pedaler working at 150W the speed drops to 2.3kts. The propeller efficiency drops to 60% because of the increased disc loading.
Two pedalers working at 300W combined could get 3.1kts in calm conditions with smooth hulls. This is based on spinning two 17X18 props with 4X gearing:
http://www.apcprop.com/product_p/lp17018.htm
The propeller efficiency is 70%.
The gearing could be achieved with two Mitrpak boxes similar to those used on Peccadillo. The top box is T-122-M:
http://lampin.com/p/mitrpak-t-122-m-right-angle-gearbox-135876/
The submerged box is an R-102:
http://lampin.com/p/mitrpak-r-102-c2-m-right-angle-gearbox-135890/
That combination gives the 4X speed increase.
With one pedaler working at 150W the speed drops to 2.3kts. The propeller efficiency drops to 60% because of the increased disc loading.
Obviously a much lighter HP having displacement like Bucket List would be consierable faster with the right set up.
I did get some positive feedback from Team Sea Runners with regard to the R2AK on the curved shaft and folding prop:
"Team Sea Runners - Race to Alaska Rick the quick reply is that the pedal drive worked flawlessly the whole way. Nothing broke and we didn't treat it too nicely. One chain change out to go from heavy chain lube (Lanacoat) to light chain lube (T9) when the water got colder and the Lanacoat gummed up the first chain. Through all the debris, landings and pushing off the beach tired and forgetting to lift the prop it just kept spinning! Unfortunately we had to spin more than sail but that's the nature of the conditions you meet in a race. When we recover we will give you more detail"
Rick
"Team Sea Runners - Race to Alaska Rick the quick reply is that the pedal drive worked flawlessly the whole way. Nothing broke and we didn't treat it too nicely. One chain change out to go from heavy chain lube (Lanacoat) to light chain lube (T9) when the water got colder and the Lanacoat gummed up the first chain. Through all the debris, landings and pushing off the beach tired and forgetting to lift the prop it just kept spinning! Unfortunately we had to spin more than sail but that's the nature of the conditions you meet in a race. When we recover we will give you more detail"
Rick
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Posted by: 63urban <63urban@gmail.com>
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