I also checked for that form too. I ran Godzilla in order to look for promising forms with the constraint of being a relatively wide and short monohull. Looked a little bit more like a surfboard than a Cadence, but it comes back to nearly 500 Watts.
Here is a picture of my design. It is parabolic/elliptic until about 50%, then straigth/elliptic until short before stern and then elliptically flattens out. Looks a bit like a catamaran hull.
It is only very loosely based on the Godzilla study, as I redesigned it from bottom up, once I knew the direction to go. I improved it for manufacturability and equal pressure rise/drop for the cost of only a few single Watts and due to the straigth part, it can be manufactured for different displacement without additional price now if the negative form allows it.
I put all my time in developing this hull since I stopped the Waveless hull. I stopped it because it was not so easy to board and there was not so much need for a super short boat in the community.
I will try to initiate an Indygogo or Kickstarter campaign to get a styrofoam positive form which I can laminate to and test it in a real tow tank. Right now, it seems to outrun other fast designs by minimum of 15%. The only drawback (there always is one) is a slightly higher drag at 2 m/s speed compared to parabolic boats. At this wattages no one will be sorry.
After restricting length to 5m, minimal radius to 1cm and adding a wavepiercing bow, my final design has 358 Watts (hello olympic hull, only 1 Watt to optimize ). But this design is much easier to handle and a lot stronger (I build things for durability, as I construct car parts in my real job and european cars have to hold for 15 years under stress).
Wish you all a merry christmas and will keep you posted.
Scheny's boat hull design
Ok, so the next question is how one stays upright with your hull. Do you intend to have outriggers, or possibly dual hulls?
Merry Christmas to everyone!
It is designed as an "stabilized monohull", like an evolution to Rick Willoughby´s work, but you can theoretically use two of them for a 2 seater cat. I also evaluate using my design for a 1 seater cat, but as it is impossible to get a lot below 450 Watts, I lay emphasis on minimizing the overall dimensions while keeping Watts low.
The other work I am curently on (since three years) is an affordable drive train consisting only of non-corrosive plastic material. The clou is, that design life is in the area of 5000 hours at 580 Watts or nearly unlimited for 150 Watts and replacement parts will be in the area of 15$.
Only drawback is the high rpm in the area of 1200-1600rpm. This helps using smaller props (for lower drafts of 23cm overall) with 88% (competition) or 82% (high thrust & weed shedding) efficiency. For lower rpm the gears would get to big (above 15cm diameter).
Greetings from Austria,
I attached pictures of the folding prop that I made. It is 14" diameter (356mm) by 23.3" pitch (591mm). The blades are stainless steel. I made the hub from Delrin. The hub is threaded for a 5/16" drive shaft.
An "aggressive cruise speed" of 10 kph (6.2 mph) sounds overly optimistic to me considering the mechanical losses in the drive mechanism and the additional drag of a rudder. From the OP video, it looks like about 3 to 4 mph and the capsize stability looks like it might be a problem.
The speed vs. time graph posted by the OP looks suspicious in that there is only one contiguous stretch of 10 kph. The ups (bursts of speed) and downs in his test run are like "stop and go". I would expect something more consistent like the performance graph from a recent row I did.
Has anyone seen one of these pedal powered boats? I've seen 3 or 4 of the Hobie Kayaks with the pedal powered "wings" on Texas lakes in the past year, but even they are kind of scarce.
I will stay with my 200 year old Thames Rowing Skiff oar powered design until I see some real evidence of high performance pedal powered boats.
Sailor Don - Lake Livingston, TX
Prop driven pedal boats do seem to be in decline, though there are still a few that run in kayak/canoe races in the USA and world wide.
PS: I got this from Rick Willoughby May 23, 2014:
"I thought you might have some interest in the Missouri River races this
Greg K plans to run his CP2. It has been strengthened for the trip. Some
There is also a three person boat being built by Scott Reeves in
Springfield. He has a building blog here:
I have supplied two pedal drives for this 9m long boat. There will be a
third station for paddling or resting. They run the 340 miles in one go.
So something over 30 hours if all goes well."
:D "The Titanic was the finest ship afloat, ten minutes before it encountered Reality. "
Early 1900's retro sneakboat on display in the Halifax Maritime Museum:
Young people may be reckless, but old people are dangerous.
Some other great benefits of a folding prop:
-Cranks don't keep spinning with force with possible foot tangling when you stop pedaling.
-Better coasting when you stop pedaling, good for start and stop situations.
-Lower draft/breakage possible as collisions fold back blades on sandy bottom or coast over tree branches.
-Shorter length & compact storage when folded for travel.
I haven't found weed shedding to be all that great (especially in stringy weeds or heavy pond scum) with any prop system. Stopping and coasting then restarting does clear minor tangles at times. Rick mounts still his folding prop close enough to be cleared by hand in some designs. I haven't had any luck by cutters, inefficient "weedless" props, cages, etc. The Hobie pedal fins are better with weeds and canoe paddles the best, IMHO.
Hope this helps.
Here is the prop info from JavaProp
Diameter D 0.3556 m 14.00 in
Spinner Dia. Dsp 0.0355 m
Revolutions per minute rpm 640 1/min
Velocity v 5.364 m/s 12.00 mph 19.3104 kph
Number of Blades B 2
Solidity sigma 0.0506
v/(nD) 1.414 v/(OR) 0.45
Efficiency ? 88.589 % loading low
Thrust T 99.09 N Ct 0.0545
Power P 600 W Cp 0.0869
Q 8.95 Nm Cs 2.3049
? at 75%R 75%R 35.2° Pitch 591 mm 23.27 in
r/R c/R ? H/D r c H t Airfoil
[-] [-] [°] [-] [mm] [mm] [mm] [mm] [-]
0 Spinner - - - - - - -
0.05 Spinner - - - - - - -
0.1 0.0168 81 2 17.8 3 709.3 0.3 interpolated
0.15 0.0346 75.4 1.8 26.7 6.2 642.7 0.7 interpolated
0.2 0.0547 70.1 1.7 35.6 9.7 615.7 1.1 interpolated
0.25 0.0743 65.1 1.7 44.4 13.2 602.1 1.4 interpolated
0.3 0.0914 60.6 1.7 53.3 16.3 594.4 1.8 interpolated 193, Re=300'000
0.35 0.105 56.5 1.7 62.2 18.7 590 2 E
0.4 0.1148 52.7 1.7 71.1 20.4 587.6 2.2 interpolated
0.45 0.1208 49.4 1.6 80 21.5 586.4 2.3 interpolated
0.5 0.1234 46.4 1.6 88.9 21.9 586.1 2.4 interpolated
0.55 0.123 43.7 1.6 97.8 21.9 586.4 2.4 interpolated
0.6 0.1203 41.2 1.7 106.7 21.4 587.2 2.3 interpolated 193, Re=300'000
0.65 0.1154 39 1.7 115.6 20.5 588.3 2.2 E
0.7 0.1087 37 1.7 124.5 19.3 589.6 2.1 interpolated
0.75 0.1004 35.2 1.7 133.4 17.8 591.2 1.9 interpolated
0.8 0.0904 33.6 1.7 142.2 16.1 593 1.7 interpolated
0.85 0.0785 32.1 1.7 151.1 14 594.9 1.5 interpolated
0.9 0.0641 30.7 1.7 160 11.4 596.9 1.2 interpolated
0.95 0.0453 29.4 1.7 168.9 8 599 0.9 interpolated 193, Re=300'000
1 0.0023 28.3 1.7 177.8 0.4 601.2 0 E
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