Pedal Powered Boats

Tom:

Worm gears cannot be used in a gearbox because they are higher friction and lock up in the position where they stop, plus they only work in the REDUCTION direction. The sprockets in a HBP would have to be huge to compensate to drive a reduction gearbox with the large ratios of a worm.

The cost is higher for the mitre type, they are heavy, and failure is mentioned more often in posts than the sprocket sections. Down time in case of failure for the free repairs is long, unless you happen to carry a second gear box with you (more weight or paddle/tow back). Maybe twisted chain sprocket systems without a gearbox section are better in reliability/repair ease? Lubrication maintenance might be a consideration with pure chain systems unless they are in a sealed case, like Bob Stuart's spinfin? http://microship.com/bobstuart/spinfin.html

I don't know if a breast drill box would be more reliable than the mitre type, but it would make for a lower cost, more compact, easily portable type that could be carried on for aircraft travel, as an example....


Porta

 

Thanks, Coach Dave. Looks like it would be difficult to adapt directly to pedals due to offset shafts, but might work with bike sprocket combinations. Looks like not as strong as a mitre type for racing/heavy use, but lower cost, you could carry a spare with you....

Porta

 

Portacruise
Do you know if that Lakerunner is still available?
Thx
JD Schaefer

 

JD:

Don't know, that was a long time ago and I haven't had any more contact.

P.

 

Hello Adrian,
in 2010 I built a bigger platform (using carbon and glass fibers, epoxy resin, foam).
I published two reports (in german) - keywords are "cruising seacycle" and "minimal-hausboot".


Best greetings
Clemens

 

Dear forum
I'm developing a college project (industrial design) of a manually operated outboard motor.
the idea is to use a back and forth movement, similar to rowing, to rotate a propeller.
I sail but I've never payed much attention to motors so it's turning into a headache, but its a FUN project.

The reason I'm writing is to see if someone can guide me in the calculation process, as I'm kind of stuck (I've been reading up to page 50 but didn't find an answer yet)

Given the boat specifications http://www.zodiacmarine.co.uk/boat/4/cadet-260-aero (a 2,6 m inflatable tender)

The total weight= 30 Kg (boat) + 2 persons (70 Kg each) = 170 Kg

The desired speed= 2 knots

given a determined propeller DxP

and the power input= 100 watts (I'm guessing that since it's arm power it would be less although Greg KolodIejzyk told me it wouldn't be far)

cadence= 60 rpm Just to make it simple, the reality is one back and forth movement per second (transmitting power in both directions) 0,66 rev per sec

How many rpm (output) are necessary to achieve the desired speed?
Is there an equation to estimate this? just to approximate the results. I know there is a relation between the hull and weight (drag) and the efficiency of a given propeller, but I don't know in what degree it affects the theoretical pitch of a propeller.

Would a propeller in the range of a 12 in diameter be appropriate? what would be the required pitch then?

ANY information will be appreciated
thank you soo much for the time and this thread, so far I've been able to collect a lot of data.
Fede, from Argentina

 

I have said this before ..This is a Student project so it should be done/researched by the student...thats why it was set to see what the student could come up with .....asking someone to tell you the answers to your questons is not what was intended .......if you dont agree then tell us who did your PHD for you ???

 

As this is a student project, where you need to do the thinking, all I'm going to do is give some pointers to show how you can go about working out a solution to this problem.

First of all, you need to know what the resistance of the hull is - how much force does it take to make the boat move at the desired speed? You can either calculate this theoretically, or you can measure it practically (by a towing test, for example). Either method will give adequate results for designing a propeller system.

One you know the hull resistance you also know the thrust that the propeller need to produce. Knowing the thrust needed and the power that's available (100W is a reasonable estimate) you can then start to look at choosing a propeller. You may have seen mention in this thread of Javaprop, that's an easy to use programme that allows fairly quick "what if" evaluations to propeller design. Remember to set the conditions for water before you start to use it, though, as it defaults to those for air.

You should now have settled on the sort of propeller diameter, pitch and rpm that can deliver the performance you need, so can design the drive system to provide the required propeller rpm and torque. There are examples earlier in this thread of systems that turn the back and forth movement of cables into near-continuous rotary motion of a propeller shaft that might be worth looking at.

If you follow the above method, of finding out the hull resistance at the speed you need, using that to define the best propeller (an iterative process of trial and error) and then design the mechanism to drive the chosen propeller you should be able to produce a good student project report. The method you demonstrate in designing your project may earn greater credit than the end result.

 

Monohull Boatbiker across Channel between UK and the Netherlands

Boat biker

A Iranian named Ebrahim Hemmatnia is pedeling out on a monohull pedal driven boatbike.
Here is de you tube film:
http://www.youtube.com/watch?v=YQpKcV5bwPU

Here is his personal webpage with personal and remarkable statements although John Lennon did the same thing in his song Imagine.
http://hemmatnia.com/

 

And here is a pedalo which reaches a speed of 14km / h produced in Poland
I'm sorry but poorly know English.

http://www.hypeboat.com/

 

Hypeboats look cool. And at least the 2 seater looks fast too. Any ide of the pricepoint?

 

Price 2 passenger in Poland about 6500 zł or about 2,000$

 

Thanks a lot guys for taking the time to answer and doing it so this way.
I don't pretend to just grab an answer but to understand the concepts and find the most suitable solution.

The project itself is to come up with an idea, develop a product and come up with a prototype at the end of the year. I'ts a short time for such a long process, and so they encourage us to get into the subject, find referents and communicate to absorb as much information as possible. This is what happens in class each correction day. The teacher acts more like a consultant than a teacher, more like a professional than a professor.
This said I would prefer this to being marked as a student. Or as it was a personal project, a hobby, as many I found here (in fact this is how I see the project). I'd be more comfortable, but it's your choice.

So here is an update, since your reply I've been trying to gather information on how could it be calculated, I found a frictional resistance formula and information in this charts as reference http://www.oneoceankayaks.com/kayakpro/kayakgrid.htm. I got stuck at defining the coefficient of friction Most important of all because I was not sure about the amount of influence the added weight would have in drag. Given this, on Sunday 26 I made a towing test (photos http://imgur.com/a/ihT2Q)
...and these are the results:

Boat alone weight: 35 kgf (without additional load)
at 2 knots= 1 kgf
at 4 knots= 4.2 kgf

Boat weight: 35 kgf plus an additional load of 253 kgf (3 passengers)
at 2 knots= between 3 and 4 kgf
at 4 knots= between 14 and 15 kgf

..it is quite a dragger..

Boat: http://www.zodiacmarine.co.uk/boat/6/cadet-fastroller-285

So to sum up I am aiming at a speed of 2 knot with a needed thrust of 40~50 N

I have been playing a little with javaprop, mainly with two diameters 300 and 350 mm, by the way I took 356 as the number of rpm I would be able to generate.
What I've realized is that DxP is not enough to define the propeller, so I'm getting doubts about the airfoil tab, what parameter should I use? this post (http://www.boatdesign.net/forums/props/propellor-pedal-powered-catamaran-21911.html#post194074) says to take the E193 profile with Re# at 100,000 but in what stations?
I am wondering If a hobby plane propeller would be a good choice for testing it (with a P/D ratio = 1). I'm not aware if the geometry of those are appropriate. If there is a standard one, what should I go for?
Finally, about loading, I've read in the manual that low to medium is the parameter recommended

The subject clearly exceeds me, but on the bright side every time I re Read a post I see something new that clears out.
If there is something to correct please do tell me and I'll find the way to make it right.

ps. The settings I´m using are "density 1000 kg/m³ for fresh water, kinematic viscosity 0.0000013 m²/s, speed of sound 1447 m/S" from one of Jeremy's posts

 

Good job!

Those figures sound about right for a fairly draggy hull. The prop sizes are a good starting point, too.

Try using an E193 aerofoil for all the outer stations, that's a section commonly used on model aircraft props, with maybe something thicker for the centre, maybe a Clark Y.

A model aircraft prop would be a good starting point, but get one with as coarse a pitch as you can find, and make sure it's one intended for a glow or diesel engine, rather than a lighter construction electric prop. The APC props are pretty cheap and tough.

 

Thanks!! for the encouragement

As for the model prop I still can't find one with a P/D ratio >1 The closest I found locally was a 12x12 or a 14x10 (for each diameter proposed) I'll keep on searching.
I found a lot at Bolly (I would have to ship it tough) but I'm not getting any reply.

Now for the javaprop prop, I tested some parameters but I have still some doubts on how to use it. Attached there is the design chart itself (http://i.imgur.com/HURBu3Q.png) and some views of the delivered prop.

About the airfoils, are they correctly arranged? and is it OK for the angle of attack to be constant?? I mean, a sail changes it's AoA to gain efficiency, but is it worth it if the construction of the prop is going to increase as well.

This is more of a confirmation, when you told me about the required torque. This is calculated in the multi analysis tab right? i.e max torque= 2.1 Nm. This will determine if the gearing I have in mind is apropiate or too demanding... I'm working with a high gearing 9:1 (2 stages of 3:1) to get the 360 rpm.. this is due to the fact that the input is 240° (120°*2 back and forth movement) instead of a full turn.