Pedal Powered Boats

Rhinox,

I'm thinking a used kayak with the potential for pedals.

You could get a surf ski if you think you could learn to balance/paddle/pedal it.

I know you're a very capable guy but do you think you're up for that?

It would make a great pedal boat candidate down the road.

 

Hi Rhinox,

Good to hear from you again. Now that you have your input power estimated at 200 watts and you are thinking of building your own boat you have some key design decisions to make.

1) What is your total displacement goal (weight of you, hull, drive train, seat). Are you making a solo, tandem, tandem + dog + food/drinks + gear?

2) What hull configuration do you want? Mono, cat, tri? I am fond of narrow stabilized monohulls for reasons already discussed on this thread.

3) Do you have size constraints where you store the boat limiting its length?

4) Do you want to optimize for short sprint speed, a 1/2 hour run, several hour or all day cruise?

5) Set an efficiency goal - maybe 75% of input power becomes your effective propulsion power.

Once you specify these basic parameters you can use Godzilla to optimize the hull(s) and answer some "what if" scenarios.

Dave

 

DIY often costs 2 - 5 times more than planned in money, time and collateral damage (emotional).

Most don't make it all the way through to fruition.

 

Rhinox:

There's no shortage of great, but idle HPboats for sale at discount prices- but connecting with the owners is the issue. Maybe post a "boat wanted" with your $1K limit to see what comes up on the HPB list:

http://hupi.org/archives/hpv-boats/2012q2/date.html

There was recently a Yamaha lakerunner posted for sale. Greg K's ocean boat is for sale and there have even been hydrofoils posted.

Hope this helps.

Porta

"The pleasure of buying a boat is only surpassed when it is finally sold"

 

Tom
I agree with your comment about cost of DIY. Also when estimating time to make it, take your worst estimate and multiply by 4.

Rhinox
Make your drive system first and then get a boat or build a boat to suit.
Its a lot harder to get a hull and then try and get a drive that will fit and work.

Ian

 

Thanks I57.

I included time as part of my 2 - 5X cost estimate, same with mental suffering which comes in all forms of course.

It's not true for everyone but is, unfortunately, common.

Rhinox has agonised for years over what to build and hasn't even started yet!

I see it as a real shame as this takes away from the time he could be spending on the water.

He'll find his way.

 

Godzilla run

Rhinox,

I did a Godzilla run assuming 435# total displacement (375# + 60# for boat & drive train) and 24' length with the search parameters pretty wide open. That yielded
T (m) , 0.161042 (6.3" draft)
B (m) , 0.337929 (13.3" beam)

That is basically a 47% wider version of Rick's V11
http://www.rickwill.bigpondhosting.com/V11.htm

I attached a speed vs. power plot that shows 135 watts of effective power (input power * efficiency - parasitic drag from other under water elements and air resistance) required at 7 MPH. This should give you an estimate of an "optimized" monohull performance. I showed results up to 12 MPH to give you and idea of the sprint performance.

Dave

 

Well that's pretty interesting CD. Can you give the graph a degree of accuracy?

That would be right up Rhinox's alley... if he hadn't disappeared, again.

 

Godzilla run

I made the graph using the Godzilla / Michlet results. I did some searching and found a thread about the accuracy.

http://www.boatdesign.net/forums/design-software/michlet-30472-3.html

I don't have the instrumentation to test accuracy but Rick commented several times in that thread about accuracy. He designed several hulls with Godzilla / Michlet and seems to be pretty happy with the agreement between his measurements vs. the predictions. So I am thinking the graph should be "close enough".

Dave

 

CD,

Thanks.

I concur.

 

What do you guys think about the Shuttle Bike?
http://www.shuttlebike.com/
I got a bicycle trip in the planning stages ....
gonna use a fat bike, and I have a few water crossings .....
this might be just the ticket?
It'll be a two week trip I'd guessimate.

my only concerns is will a fat bike fit,
and can it carry any weight?
I got an email off to them .....
most of the weight will be drinking water.
I got to carry about 4 gallons for the longer stretches.
I'll be unsupported except for re provisions at towns.

yeah, by now I can build a similar device,
and the cart I tow can also be the bike platform ....
there's pros and cons of course !

build or buy?

 

If your few water crossings are short, why not a packable, rowable, inflatable raft and find a way to carry the bike on it? The pictured bike conversion is inefficient friction drive to the prop and very high profile which is not good for crossing large distance of open water. There is a similar model made in Oz where you remove the rear wheel to get direct drive to the prop, but still high profile. The high profile might be ok in protected waters, some have used them on canal tours in Europe...

Hope this helps,

Porta

 

so this is a bit more stable than I originally thought.
but I'll have my camping gear and drinking water (4 gallons?)



I'm also considering something like this:
https://www.alpackaraft.com/index.cfm/store.catalog?CategoryID=53
but now this is getting a bit off topic ....

 

V15-i

Been busy upgrading my boat from an inline shaft to a side mounted shaft. Same sort of setup Rick uses, have put on one of his folding carbon fibre props. Inline shaft was awkward for launching and transport. Put in a 52 tooth chain ring connected to a 15 tooth gear off a 90 deg 1:2 ratio gearbox.
Shaft is 10mm dia aluminium 2.3m long. Gear ratio is 1:6.9 which gives me about 13-14kmh at 100rpm cadence, feels a bit light. Putting in a 14 tooth gear this week to bring the ratio up to 1:7.4, will be a bit harder to pedal but should give a higher speed. I can go to a higher ratio with a 13 tooth gear or even a 12 tooth gear but whether thats too high I'll have to see. Haven't changed the rudder, under the hull is the most efficient but dosen't let me sit the boat flat on the beach. Have to work out which is better a kick up rudder that is less efficient or stick to the one I've got.

Ian

 

Hi Ian,
That is a great looking boat! It is a beautiful calm sunny morning here and would be a perfect day to be on the water..........if my boat was finished. Just wondering what the specs are for the prop you are using. I am building the cat first so my requirements will be different and I expect the single hull version will still be heavier and slower than yours.
Cheers, Glen