Kayak Propulsion.
Kayak Propulsion.
(OP)
Is anyone interested in brainstorming kayak propulsion methods?
Something got me started pondering possible methods of kayak propulsion.
Hand power or foot power?
I tend towards hand/arm power.
What will be the most usable?- Push-pull with handles near vertical, or up-down with the operating handles near horizontal?
What will be the best means of power transfer, mechanical, electric, hydraulic?
For cost and weight, air cylinders are attractive. What would be the best fluid for a hydraulic system using air cylinders?
Lots of other questions.
Any discussion?
Bill
--------------------
"Why not the best?"
Jimmy Carter
Something got me started pondering possible methods of kayak propulsion.
Hand power or foot power?
I tend towards hand/arm power.
What will be the most usable?- Push-pull with handles near vertical, or up-down with the operating handles near horizontal?
What will be the best means of power transfer, mechanical, electric, hydraulic?
For cost and weight, air cylinders are attractive. What would be the best fluid for a hydraulic system using air cylinders?
Lots of other questions.
Any discussion?
Bill
--------------------
"Why not the best?"
Jimmy Carter





RE: Kayak Propulsion.
Any motion that involves moving your whole body, or significant portion there of, may be an issue for stability.
If you use some kind of a hydraulic system, you'll have to consider environmental contamination issues from leaks. i.e. water based fluid may be best choice despite some disadvantages.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Kayak Propulsion.
Use a ducted jet just like the drives on every jet-ski this will prevent any accidental contact with blades of any kind. Power it with a flexible solar array wrapped over the front and rear decks.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Kayak Propulsion.
RE: Kayak Propulsion.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Kayak Propulsion.
Lightly paddling propels me at about 5 mph. I define light paddling as 15 lb per stroke. Assuming that the force I apply to the paddle equals the force of drag on the kayak, and guessing that the the pulses of propulsion must be 50% higher than the continuous hydrodynamic drag to maintain a constant speed, then I can estimate the power required to keep my kayak moving at 5 mph. Which comes out to about 100 Watts.
For any mechanical device to drive the kayak, it will need a supply of >100 Watts to overcome its own efficiency losses. For a propeller I guess 50% efficiency, hence 100/0.5 = 200 Watts delivered by the drive. Most kinds of reciprocating paddle would get less than that, but not necessarily.
So the simplest (in my mind) is a 200 Watt electric motor driving a small propeller. I haven't worked out the appropriate speed of the prop yet because I haven't worked out the size of the prop, either. But I can tell that for this to last for 1 hour, the battery would need 200 Watt-hours, or, at 12 Volts, a 17 Amp-hour battery would be needed. Those are pretty compact (4 would fit in a typical lunch box). Without trying to make up my mind just HOW to make the propeller work, I can tell you that it CAN work, and that it won't need to be bulky or difficult to fit into a kayak.
OK
I'm sure you've already thought of a little electric motor - and you want to do something else. Otherwise you wouldn't have asked!
What energy source do you REALLY want to use? Human power? A human can generate 100 Watts pretty much continuously (at least, humans that tend to get into kayaks can) There are many ways to do it. Mechanical power? You're dispensing with the obvious paddle power, but what do you want in exchange? Speed or distance? Electric power? Solar panels suck as prime-movers for mechanical things, if you've ever tried it, but they could be used to charge a battery that is. Hydraulic power? There's a readily available source of hydraulic fluid surround the kayak, so I'd be tempted to look for ways to drive the water through or around the hull of the boat. There are many ways to drive a jet of water. But there's no way to store it on board or make complicated intrusions into the hull - not if you expect the kayaker to enjoy paddling it, too.
PS I make no excuses for intermixing metric and stone-age units.
STF
RE: Kayak Propulsion.
Peddle-powered propeller is already on the market..
How about a swishing tail or serpentine motion? Perhaps generated by a T-bar footrest (some now control a small rudder).
Issues to look at:
- Stability (as KANAT mentioned) - maybe provide some outriggers?
- Available room and comfort for constant leg motion.
Application may be limited to lakes and calm rivers.Will be waiting to see what you come up with!
Gary Bangs
www.flowserve.com
RE: Kayak Propulsion.
Maybe stability improvements to the hull to work more harmoniously with the paddle motion.
The problem with getting too fancy is that inefficiencies can quickly add up to negate the gains.
RE: Kayak Propulsion.
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
RE: Kayak Propulsion.
A couple of points for discussion:
Hands vs. feet: Traditionally kayaks have been paddled by arms and upper body. Many solutions to alternate propulsion use foot power.
What thoughts on arms vs. legs, not just on maximum power but also on stamina?
A jet drive has been mentioned. What kind of efficiencies can we get with a jet type drive?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Kayak Propulsion.
I'll see if I can find out when they have their next event and get an idea of the details, maybe some pictures.
MikeL
RE: Kayak Propulsion.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Kayak Propulsion.
If you want to get into this I suggest reading the IHPV website, in between the loons there are a lot of people with experience.
also
http://www.gizmag.com/go/7402/
and
http://www.openwatercycling.com/
and my fave
http://lancet.mit.edu/decavitator/
and the granddaddy of them all
http://flyingfishhydrofoil.com/
There's no doubt that legs are better than arms/upper body alone, in terms of power vs endurance. A quick glance in the mirror before it cracks will show why.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Kayak Propulsion.
I wonder if a Kort type nozzle or ducting would supply any advantage at the low speeds and fairly low propeller loading of a man powered craft.
Comments?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Kayak Propulsion.
I'd expect similar may be true in liquid jet propulsion.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Kayak Propulsion.
Nobody buys a jet boat for its fuel economy.
Most people are amazed and dismayed at the amount of fuel a jetski can burn in an hour of hooning around.
However, a Kort nozzle brings several advantages to an otherwise open propeller, including the ease of turning the nozzle into a guard to avoid unintended interaction with swimmers, and lawyers.
Kort nozzles are almost universal on tugboats, so there must be other advantages that accrue at low speeds.
Mike Halloran
Pembroke Pines, FL, USA
RE: Kayak Propulsion.
I agree with your assessment of jet ski efficiency.
Kort nozzles are interesting. My reading indicates that they are most effective below about 10 knt. Above about 10 knt the drag offsets the advantages.
For slow speed they are claimed to increase the bollard pull of a tug boat up to about 30%. That's at full power.
My concern is that at the relatively low power and speed of a human powered craft, the performance may become non-linear in a negative fashion.
We may have to test a model to find out for sure.
Any other comments?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Kayak Propulsion.
Also the issues with dragging a kayak on/off shore. A propeller has no chance there.
It's also unclear if you're trying to go really fast or just leave one's hands free for steering, photog, fishing, etc.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Kayak Propulsion.
I am thinking recreational. Easy to use. No speed records. Easy to retrofit. What has a chance of working, what is a good idea, what is probably inefficient.
Kick ideas around.
Thanks to you and everyone else for participating.
Yours
Bill
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Kayak Propulsion.
http://www.torqeedo.com/en/products/outboards/ultr...
Bring your wallet.
... but even fully accessorized, it's probably cheaper than anything proposed above.
Mike Halloran
Pembroke Pines, FL, USA
RE: Kayak Propulsion.
That little electric outfit may be a valuable benchmark to compare human power schemes against.
It may eventually come out the winner.
I wonder about a pedal power generator to charge the battery?
How do we calculate the efficiency of charging a battery?
Yours
Bill
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Kayak Propulsion.
If you lose the retrofit aspect and don't mind bringing a full wallet, I still really favour Hobie's "penguin-fin" propulsion system; they make kayaks for two, leg-powered, fins self-clearing when it comes to weeds.
Unless of course there's a way to cobble up a similar retro-fit for less money, particularly if you already own a kayak...which you didn't specify in your OP, Bill...
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
RE: Kayak Propulsion.
manperson.I like the "penguin-fin" propulsion system. Will that system allow you to coast, relatively drag free or do you have to pedal continuously? I wonder, if you find yourself in shoals, how difficult is it to get back into deep water with this system?
A system where the Kayak could be launched (single handedly) and then have the propulsion system pinned into place would be nice.
But this thread was intended to be a general discussion. I hope to explore as many types of propulsion as possible, and discuss the pros and cons of each.
Please don't try to please only me.
I am not the only one here with a kayak. Different folk may have different criteria.
Let's keep this a general discussion.
Thanks for all the suggestions.
Yours
Bill
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Kayak Propulsion.
Most of the problems with human-powered propulsion are human. Good paddling takes proper technique. It also requires sensitivity and awareness of one's interaction with the water. Most casual paddlers exercise neither.
RE: Kayak Propulsion.
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: Kayak Propulsion.
I find this is what separates the good paddlers from the dippers and flailers. The good paddlers are constantly aware of the feedback of their paddle. They waste less energy on splashing or other pointless motion.
Perhaps there is room to innovate on this front. Paddles that better transmit feedback? Propulsion systems that respond to and minimize inefficiencies?
RE: Kayak Propulsion.
The ideal mechanism to drive the fin was not obvious to us, which is why we eventually abandoned the project.
It needed to be robust and watertight, but at the same time needed many reciprocating elements sticking out.
Maybe some ideas can come up here that we weren't able to think of then.
STF
RE: Kayak Propulsion.
>Legs are far more powerful than arms.
>Human power is very limited so efficiency is of utmost importance. This rules out high velocity jets.
>As a scuba diver I can attest to the amazing efficiency and simplicity of swim fins. Applying them to a kayak may not be simple.
>Wind resistance is an important factor to consider. Kayak paddles are usually set for the paddles to be 90 degrees from each other so the paddle in the air does not act as a sail to retard forward motion.
>A paddle-wheel mechanism would be very efficient but heavy and with high air resistance.
>Water resistance needs to be considered, particularly when when not pedaling.
It is always best to learn from the experience of others before reinventing the wheel. Thus it pays to look at what others have tried before:
https://www.google.com/search?q=human+powered+wate...
RE: Kayak Propulsion.
https://en.wikipedia.org/wiki/Human-powered_aircra...
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Kayak Propulsion.
I.e., a retrofit may require its own exoskeleton (and associated weight) just to keep from breaking the basic kayak.
That will almost certainly raise the CG of the modified kayak, compromising its roll stability, which is also not helped by the up/down dynamic inertial forces of flexing legs, not ordinarily of much concern to a kayaker.
In the interest of roll stability, you may end up with a proa.
Mike Halloran
Pembroke Pines, FL, USA
RE: Kayak Propulsion.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Kayak Propulsion.
BUT
As it is it would leave the person much too high in a kayak. That said, the pivot points are not that low, and it is the placement or location of the pivot points that determines the characteristics of the machine.
A thought; Instead of the work arms going down from the pivot, how about riding Between the persons legs and then curving out to both sides to end up in the same position for the handholds?
The hydraulic shock absorber could be swapped for a cylinder to extract energy. The cylinder would be mounted towards the front instead of towards the back.
I'm thinking that the mechanism, that is the seat, the seat rails and the handle bars may be able to be inserted into a conventional kayak without structural modifications. It would depend on the size of the cockpit.
But the other problem remains; how to efficiently get the energy transposed into forward motion.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Kayak Propulsion.
So I return you to my first point in my first post.
"Stability and steering need to be considered not just the propulsion."
(By the way, am I the only one who finds it a little ironic that you're considering copying an exercise machine configuration that in is in turn mimicking a rowing motion from a scull or similar human powered waterborne vehicle. One might suggest going the other way, i.e. modify a scull to better do whatever it is the kayak is doing that a regular scull or 'row boat' doesn't.)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Kayak Propulsion.
Good point KENAT. GRIN
The method of harvesting energy shown in your animation is interesting. The flywheel and recoil device may possibly be mounted on the fore deck of a kayak. Thanks.
I agree with the advantages of arm and leg movement for maximum power, but my kayak and many others do not have room in the cockpit for leg movement.
We have two design areas yet to explore in depth;
Transmitting energy to the propulsion device, and the propulsion device itself.
TheTick's comments may be foreshadowing some challenging efficiency issues.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Kayak Propulsion.
Kind of putting it all together:
Ease of use, least effect on stability, easy to retrofit, fairly good efficiency (I hope), Use of mostly off the shelf components with not too much modification or building from scratch. This may not appeal to everyone for various personal reasons but for me it may well be the Biggest Bang for the Buck.
The first component would be one of those small electric motors suggested by MikeHalloran.
http://www.torqeedo.com/en/products/outboards/ultr...
We can add a pull rope type exerciser as suggested by KENAT with an alternator added to charge the battery. I believe that the for and aft motion will allow upper body strength to augment arm power while having the least negative effect on stability.
We can add a draped solar array as per itsmoked's suggestion and have the battery on charge even while taking a picnic break.
For some folk this may be the ideal solution.
A compromise between easy installation, ease of use, efficiency and overall usability.
This may also end up being one of the most economical solutions as well.
Comments are welcome.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Kayak Propulsion.
There are literally hundreds available for less than $200US. Where do they get off charging $1,700+??!!!
$900 for a 45W solar panel!! That's only about 8 times markup...
ebay flexible+solar+panel+boat
Keith Cress
kcress - http://www.flaminsystems.com
RE: Kayak Propulsion.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Kayak Propulsion.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Kayak Propulsion.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Kayak Propulsion.
... where the reviewer recognized that the prices were quite high.
... but asserted that you got German Engineering, when that was a good thing.
... and that there was nothing else like it for sale at the time,
i.e., an outboard motor with usable thrust, decent range and silent operation, that you could stash in a carry-on, and actually carry.
I'm not sure if there are direct competitors to the original product even now, but they have expanded their product line upward quite a bit.
Mike Halloran
Pembroke Pines, FL, USA
RE: Kayak Propulsion.
However, "price gouging" The two words strung togehter, is usually associated with illegal prices tied to shortages. That's probably what you were thinking.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Kayak Propulsion.
Price gouging implies an "on the fly" price increase for whatever reason (people are waiting in line to buy your limited edition widget, 49 sold and the final 50th one you double the price and see if the rest of the line goes home, or someone buys it.)