Pedal boat propeller specifications data

Hello folks!
I'm looking to build a pedal powered sea fishing canoe but found there is a lack of detailed info on ANY pedal power props.
I therefore think it would be useful for all pedal boat builders to have a reference database/thread of props used in various designs. Most of us know the basics already and are building our own boats, so no need for distracting discussions of the merits of one over the other, this is purely for data.
If you have built a prop pedal boat it would be immensely useful to others if you could post some info on the prop, anything at all, even if you don't know all the answers, like:

Diameter:
Pitch:
Blades 2,3,4:
Material:
Blade Shape (like scimitar, narrow, wide, aspect ratio or whatever):
Blade material thickness (say in the centre of the blade)
RPM (design speed)
Gearing ratio (from pedal to prop)
Cadence (your pedalling speed)
Boat type: (species, size, number of people carried)
Speeds achieved: (cruise, burst)

Any other data you find useful.
Photos+links : web links to such info, pics of the boat+prop etc. would be great!

If you'd like to discuss something, please start a different thread and link to it, hoping this thread will fill with DATA ONLY!

 

Prop data without hull data for HPVs is next to useless. Because the power is so small, the adapation of the wheel to the wake for the design condition is more important than the apperance of any data.

So, for what it is worth, the wheels I have designed and built have had: diameters from 0.56 to 0.95m
P/D from 1.1 to 1.35 wake adapted
BAR 7-15%
Thickness <10% chord
Geared up 2.5:1 to 3.5:1 variable
Counter-rotating 2-bladed
Forward skewed and tapered
Twisted off tips
Generated ~40 lbs thrust @ 7 knts with ~3/4 hp in at the cranks or 25 lbs of thrust at 5.5 knts with 0.375 hp in (yes, ~115% effeciency, which is why I said it is useless to look at a prop without considering wake adapation).

 

You can calculate prop performance within 1% or 2% of actual performance.

If you have an application in mind I can determine how various props will perform.

As far as lack of detail goes you may not have read this thread:
ttp://www.boatdesign.net/forums/boat-design/pedal-powered-boats-23345.html

Javaprop will give answers within about 5% of actual but it has a limited array of sections and Re#.

Rick W

 

Well no, most people can't, which is why I've started this thread about ACTUAL props used in different pedal designs, not hypothetic paper mathematical program ones.

That would be great. If you could post drawings for a variety of leisure pedal boat apps, like pedal powered Kayaks and Leisure Canoes it sure would give loads of people a concrete starting point. Even just diameter/pitch/gearing ratios alone would be usable.

Yes, I did. There were pages upon pages of people waffling but next to no useful hard info on actual diameter and most importantly, actual pitch and gearing. When someone did think of mentioning it, they forgot to mention the gearing ratio, so the info is virtually useless in practice. That's the reason I don't want this thread to develop into a discussion but simply have ACTUAL USABLE DATA to make a prop for a pedal powered propeller boat. Even just boat type, diameter, pitch and gearing alone provides a decent starting point.

It would for those prepared to learn how to use it, however most garage builder's priorities are different. The prog doesn't even seem to differentiate between water and air as far as I could determine. It just kept telling me to put less loading on the prop. I'm sure it's brilliant for paper designers but it's failed my real-life practicality test. Real life info please!

 

Welcome to the world of props...note that except for some compressability issues which reduces the efficency of air props, there is no difference between air and water. FWIW, maximum efficency is achieved at infintessimal loading and infinite diameter at null RPM with nill BAR and immeasurable thrust. Optimizing on efficency will force you to this, so it is up to you to decide when to stop based upon thrust required.

 

So... before getting sidetracked again. Some REAL LIFE INFO on actual props you're using, please.

 

To calculate a prop you need to have the power input. How much HP can you produce?

 

That's a question not data. Kindly keep on-thread or start another one please. (The pedal power for an average bloke I think is about 1/3hp or 250watts). A pedal propeller boat will be powered by a kid or an athlete or anyone in between so the question still is:
WHAT DIAMETER, PITCH AND GEARING HAVE YOU ACTUALLY USED.

 

Check the archives under MCDenny in efficient electric boats. He tested various APC model plane props with a troll motor and has detailed data. Hope this along the lines of what you are looking for.

Porta

 

Another place to google is under "spinfin" made by Bob Stuart, which was a human powered unit using a 16X16 APC prop. Also seacycle, hydrocycle, cadence and other commercial HPB should give you an idea of what has been used.

Porta

 

You underestimate most people. There are many who have taken the time to learn JavaProp. With a little tuition it takes a couple of hours for anyone of average talent to pick it up to a satisfactory level for use on a pedal boat prop design. So I am sure you could.

For my own props I design for 120 to 130W and a cadence of 70 to 75. I have made many. The smallest is 230mm diameter 4-bladed that I spun at 7.5 X cadence. It has a nominal pitch of 320mm. The largest is 30" X 20" model plane prop I spun at 2 X cadence to power an 8t sailing catamaran using pedal power in a particular race where human power is permitted.

I also do prop design for a very good engine. He currently holds the world 24 hour distance record on water. For him I design at his continuous output of 150W and cadence of 80rpm.

So first off the 250W you guess at is a useless figure. The first step is to do a power determination for the engine. It can be done in many ways.

There is my recent engine data for my current folding prop that is also pictured. The heart rate of 140bpm corresponds with 125 to 130W. The conditions were very calm. There was a little fouling occurring on the strut. THe dips are where I slowed to check for and remove fouling from the strut. The folding prop has the advantage that it releases fouling as soon as I stop pedalling.

The folding prop has a diameter of 340mm and a nominal pitch of 625mm. I spin it between 4 and 5 to 1 depending on the chainring chosen. It uses a NACA 16 series section. The blades have a chord of 25mm and thickness of 3mm.

The fixed 2-bladed prop pictured is 350mm diameter and pitch is nominally 606mm.

Take a few minutes to learn how to use JavaProp and you will save a lot of time trying to collate useless information. You need to go to the Options page and set the density for water - 1000 for fresh, 1025 for salt. You should also set the viscosity to something like 0.0000013 for water.

Also take the time to determine the power output of the engine. Once you have this you only need to work out the drag on the hull so you can determine the speed at your power level and enter the data in JavaProp. A guess of the engine performance is pointless.

Rick W

 

Thanks, some real usable info there.
I have no idea what the drag of the boat will be at any time. Highly variable. In practice such data is very dependent on different sea conditions and whether outriggers are deployed or not and where the wind is coming from. It has to cope with all. It might also be switchable to electric and carry batteries on some trips. If I have a nice catch of fish, it'll be heavier on the way in. The engine is also worryingly variable in performance. How long is a piece of string? I suppose the worst case would be that of a Canoe going into wind in increasingly choppy conditions with the added possibility of braving a swell (And hopefully towing a dead Marlin from one of the outriggers). I'm hoping to keep that total weight including me under 150 Kg (not counting any dead fish)

 

The main variable will be speed.

All the other items are what any boat designer has to consider. If you want the best prop for the application then you need to pin down a few aspects.

Outriggers should not contribute significantly to water drag. They are there in-case and do not need to be immersed. They will have some windage though.

You need to estimate the weight.
How heavy is the hull?
How heavy is the engine - is there a target weight for the engine?
How much gear will you typically carry?
How mush fish do you realistically expect to bring home?
What wind strength will you want to design for - it is not the worst case but the strength you want to operate in without stress? THe wind drag can be calculated.
Typical wave allowance is 20% - to some degree it depends on the boat shape? My speed in waves is not limited by power but how wet I want to get.
If you have the hull shape and the total displacement the hydrodynamic drag can be calculated.

The engine performance will be consistent from day-to-day. It might improve with training but that will be over a period of time. If you visit a gym then a recumbent cycle machine can be used to give you power output. If no gym then a stair case in a building over 10 storeys can be used. A steep hill with a steady grade is also a possibility. I can explain any of these in more detail.

The 250W you mentioned is for a moderate to good athlete. I have attached a chart for human power output. I am somewhat trained but quite old. I weigh 70kg in racing trim so my 130W Full Time output does not rank for untrained even but then I am probably older than the test subjects for the chart. Most older adult males will struggle holding 80W if they do not exercise regularly and have sedentary lifestyle. Interestingly this is the power level that gets a Hobie Adventure to its hump speed.

The gearing depends on functional aspects particularly draft but it could be also the selection of parts. Basically a normal engineering process based on economy, parts availability and shop ability of constructor.

Rick W

 

Thanks for the interesting info, especially the chart.
Being into RC planes, the RC props are of interest not just for me but because of their worldwide cheap availability. Also worth remembering is that RC props can fairly easily be shortened to any length.

RC glow engine manufacturers provide prop recommendations for engines and type of plane (slow/fast/aerobatic etc.) Similarly, it would be fantastic if someone made a chart or nomogram of suggested RC props (and others types) for our applications. I don't want to delve into the infinite variables as I keep on saying. The fine tuning has to be done in practice, at will, and is highly variable on many factors.
What's needed is just a simple STARTING POINT for prop selection for HPBs.
Pitch-diameter-gearing.

HPBs weigh between 12-50 KGs roughly and are reasonably hydrodynamically shaped. The vast majority of people rate anything up to 'good' on your chart.
Ultimate performance of the first prop try isn't half as important as it's general usability by people of average power output (Moderate?). The fine performance tuning is largely a matter of personal choice later.
So come on folks, what props and gearing have YOU actually used.

 

Ok, I'm looking at APC Scimitar props here:

http://www.apcprop.com/pindex.asp

Of interest are:
LP16014 16x14
LP16016 16x16

I plan to overprop at first and then cut the prop down gradually to suit. Once I have arrived at a satisfactory effort level by chopping it I'll then guesstimate the nearest size uncut prop. Now it's just a question of suitable gearing... 4 to1 ?