[cjjonesarmory]

I am considering options for a pet project. My friends and I take canoe trips several times a year, and I want to build a small propulsion system for those days where we need some extra help with the paddlin'.

Gasoline or other combustibles are NOT an option, for legal reasons as well as ecological reasons.

My two main contenders are battery (electric) and compressed gas (CO2, Nitrogen/Scuba, etc). The max weight of the energy storage system by itself should be 100 lbs or less. In other words, don't count the rest of the propulsion system (motor, regulator, etc) as part of the 100 lbs.

SO, considering weight, size, power (amount and duration), and general practicality, what do you think would be the better option, battery or compressed gas, and why?

My current inclination is going with maybe two or three 10 to 20lb CO2 tanks with the gas fed trough a regulator to a 1/2 horse or 3/4 horse air motor, and using a trolling motor prop (probably make one myself).

There are a lot of electric trolling motors available, but #1, I want to make it myself, #2, Since it's going to be home-made I'm not sure about mixing water and electricity. And #3 It's going to be a "stealth" installation :-) I want my other buddies to be baffled at my supposed paddling prowess. This is a brains over brawn kind of excercise here .

But I am still up in the air about electric vs a CO2 powered air motor. I don't know how much air the setup would consume and whether the tanks would last for several hours of continuous use.... And also whether CO2 or Nitrogen would last longer.

Opinions anyone? :-)

[samco]

with electric - you could also have a small solar panel to charge..

sam

[BillTodd]

CO2 'liquifies' when under sufficient pressure so allows far greater volume to be stored than N2 (or Air).

Any compressed gas requires energy to expand, so you will probably want to 'heat' the tank (with the river water?) by some means or the tank will freeze.

I suspect that the energy density (W/kg) of LiPO batteries will be greater than CO2 (that's why they're used in model aircraft) but the cost may be prohibative.

[harryn]

The battery + electric motor concepts are much more developed and commercial. I imagine that there is also an energy density value for battery powered version but I am too tired to run the math tonight.

100 lbs is a pair of decent 12 volt Pb acid deep discharge batteries - around $ 150 - 200. NiMH cells will go further but about 2 - 3x the cost. LiPos of course are amazing, but now you are really into serious money.

One thing nice about the Lb acid batteries is that you can charge them up from your car's electrical system - while you drive. Electric trolling motors and parts are easy to obtain and while quiet, not zero noise. There are some very quiet and efficient ones for use around bass.

Air motors on the other hand - there is nothing stealth about them at all.

[Geof]

.....Air motors on the other hand - there is nothing stealth about them at all.

My thoughts exactly.

Use batteries for the reasons mentioned; recharge by solar or in the car while driving, proven technology, much more efficient and quieter.

Go for 24 volts and you can probably scrounge used wheelchair or mobility scooter bits and pieces for the controls. Be careful but don't worry too much about electricity and water when you have low voltage.

If you want to get creative make a water driven generator to charge the batteries out on the river when you are stopped overnight. I really have no idea if this would be practical; some type of folding paddle wheel that you put in fast flowing water?

[amplexus]

There are some cool brushless dc motors for model aircraft. Fit in the palm of your hand and will run a mini bike from 0-60 in a little over 4 seconds. Great power to weight ratio and dead quiet.
amplexus

[cjjonesarmory]

Thanks all for the info. You are right that air motors would not be stealthy, even under water with mufflers. I neglected to think about that, but it makes sense, my air tools are noisy! It just clicked they are "air motors" too :-)

I had another brain fart (aka thought) about using a small (dirty water style) pump. I could machine a couple of disks to fit the rear of the canoe (submerged) and install a rotating ball type fitting to be sandwiched between them. The outlet of the pump would be attached to the ball fitting allowing a person to direct the flow.... Hmmmm. The inlet could be plumbed to the bow.

Not sure how big a strong enough pump would be. Or it's weight and size, plus it's power source.... something to think about...

Another question would be pressure vs volume in a water jet system. I'm thinking pressure is more important than volume to create something for propulsion. I'm all about adaptation, so I'm trying to think if I could modify an old machining coolant pump or even an old sump pump to do the trick. Any other ideas anyone???

I think I can get by with even using some type of solid/liquid/gas fuel if it's done responsibly.

Now keep in mind this is supposed to be at least somewhat stealthy. I know there are a lot of easier ways to achieve propulsion using a fuel, but this should be a unique system and it can not be obvious to the casual observer. SO I was also thinking of steam power! Now that would be cool: A steam powered canoe! A steam engine could power the water-jet pump or the steam itself could be used to turn a turbine (an air motor maybe?) system directly in the water.

The water is plentiful, power could come from readily available propane cylinders for lanterns (something we would have anyway). Now I guess I just need to determine how much all this crap would weigh and how much space it would require!

Sure an electric trolling motor with a couple of deep cycle batteries would be easier, quieter, and overall better, but I'm going for something that people are going to find intriguing.

If the steam engine idea proves too dangerous, costly, or impractical, I will probably go back to using deep cycle batterys and a solar charger, but I think I like the water jet idea. We tend to cross a lot of very shallow water sometimes, and we've had to even get out of the boat occasionally to manually pull the boat across a gravel bar, so a prop on a trolling motor would not be ideal anyway.

Last thought with the water jet thing is instead of plumbing the outlet to the rear of the canoe, is to make a couple of catamaran (sp?) style "stealth floats". They would look like stabilizing floats (they could do that too), but would also have water jet outlets >;-). A simple valve could control the pressure going to one side or the other for steering.

Sounds like I have some experimenting to do. I welcome any input!

[CncForMe]

Nothing you could make is going to beat out this proven battery to motor technology in terms of range. And if you want the most range go lipo/life as others have already said. Car companies and everybody else would be spending millions on other research besides electric if it was better energy storage medium. Water jets i.e. a pump is very VERY inefficient at slow speeds. You want to turn the biggest propeller you can fit with slowest rpm for best range/efficiency. A trolling motor is already this and cheap.
fficeffice" />>Not trying to be a naysayer just giving in my opinion sound advise.>

[BillTodd]

If you want to intrigue, it's got to be Boiling Petrol! (gasoline)
http://www.dself.dsl.pipex.com/MUSEU...rol/petrol.htm


Loads of other ideas here:
http://www.dself.dsl.pipex.com/MUSEUM/museum.htm

[Andre' B]

Yep, the energy storage density (how far you can go) of a even a lead acid battery is going to blow away any compressed gas or any home/hobby built steam system.

Keep things low above the water line to reduce air drag, keep everything below the water line nice and smooth, keep the speeds well below hull speed and you will go a long way on a battery.

[BobF]

Back to CO2.
You could use a venturi to suck in water and jet that out the back. Wrap the water intake around the tank to help with heating of the CO2.

[cjjonesarmory]

If you want to intrigue, it's got to be Boiling Petrol! (gasoline)
http://www.dself.dsl.pipex.com/MUSEU...rol/petrol.htm


Loads of other ideas here:
http://www.dself.dsl.pipex.com/MUSEUM/museum.htm

LOL! Boiling Petrol. I bet that smells nice!

I looked at the other site too. With today's communication and vast amount of people coming up with ideas, it's hard to make something original. Seems like whenever I come up with a genuinely original (or so I think) idea on my own, I get to the ol' internet and BAM sure enough, someone's done it before, and they usually have a bigger budget than me :-) By the way, my budget is zero, plus whatever change I find under the seat cushions, plus whatever spare parts I have laying around.

So far, no stealth canoes though :-) What kind of idiot would want to make a stealth canoe anyway, lol

Thanks for the info!

[cjjonesarmory]

To Andre'B: Good advice. I doubt that I'll get a steam engine powered water jet what-not under a hundred pounds, but I'll give it a shot. Batteries are my fall-back idea.

To BobF: That's a possibility.... With whatever system I use, especially with steam exhaust and a water jet, I wonder if it could be vented through the water jet outlet for additional thrust? Not sure you'd call that a venturi system in that configuration, but your suggestion spawned the idea. I think a venturi system on it's own would consume/use too much air to be practical.

To Anyone: I keep hearing about LIPO batteries. I assume they aren't powered by human fat , but I'm not familiar with them. I know laptop batteries use lithium. Are they essentially the same thing in different configuration? Where would be a good source and exactly how much are we talking about for cost?

[cjjonesarmory]

Another thought on energy density (and I hope I am using the terminology correctly). Wouldn't an equivalent weight of propane have more energy density than a battery and trolling motor? I think a system powered by propane would have more energy density (energy potential?) than batteries. Now, granted most likely the whole steam conversion process totally hoses the whole efficiency thing, but I think a system that burned the propane in an internal combustion engine would have the most energy density.

Not sure how to calculate the energy "lost" (if any) in the steam conversion. In theory, if you could get 100 percent of the heat of a propane flame is used to heat the water, and 100 percent of the steam exhaust is ported through the jet exhaust for additional thrust, would not such a steam powered system have greater energy density (more efficient???) than batteries?

[BobF]

I think LIPO refers to lithium polymer. yes laptop batteries.

As you said "What kind of idiot would want to make a stealth canoe anyway"
Aren't canoes pretty stealthy anyway?
Spend your time in the gym and develop a more efficient paddle. :-}

[cjjonesarmory]

BobF, Yup, probably should spend more time in the gym , but so far I've found my brain is my best muscle. Well, second best maybe....

I'm just kind of known for doing weird shnit and making it work, so it's kind of a hobby. Down below in one of my previous posts I mentioned that everything that is useful seems to already be invented that is within the budget of a semi-professional hobbiest (I made that title up), so I try to find different things to do.

Getting philosophical for a minute: It's exciting and interesting (for me) to come up with mad scientist type projects rather than just "getting the job done". I already KNOW I can copy the design of something that is already done. I'm not saying my "canoe stealth motor" is going to change the world, but I think those who work outside the box tend to (usually accidently) come up with earth shattering discoveries. Again, nothing earth shattering about this particular project, but who knows what a person may learn by trying to do something that others may laugh at or say is impractical. Personally, I do it because I find it fun I may be way out in left-field, but it's a job (or semi-professional hobby) someone has to do.

[ImanCarrot]

Couldn't you rig up some bicycle type arrangement? legs are stronger than arms.

Or... train a dolphin to tow you?

I've heard there's great support for dolphins on this site... I think there's a trial dolphin or something that you can try before buying one.

[cjjonesarmory]

ImanCarrot: Problem with the dolphins, I think they need salt-water. We usually stick to freshwater rivers

[BillTodd]

It's exciting and interesting (for me) to come up with mad scientist type projects rather than just "getting the job done".

:withstupi

I agree 100%

[High Seas]

http://www.hobiecat.com/kayaking/miragedrive.html
Bet you could reverse engineer (and little or no noise). Keep all that weight for Beer! Just keep the cans!
:cheers: Jim

QUICK - Better bid before your buddies do!:
http://cgi.ebay.com/HOBIE-MIRAGE-PED...3%3A1|294%3A50

Not associated - just Wowed!:banana:

Here are some detail pics for the interested -- we all know what a motor looks like
http://www.bigwatersedge.com/bwevb/s...ad.php?p=22149
The hub assembly looks like Marelon - glass reinforced plastic - molded product. Maybe better with kevlar timing belts in lieu of chain? Sorry for the side trip here - leave today, sail from Thailand back to Malaysia - 5/10 days or so, Cheers.