Power requirement for 10m canoe

This what Gonzo is saying.
Most projects would not be feasible if they had to adhere to the letter of the SOR, but the SOR, like anything else, can be changed (also the project, I guess).
Thanks @bajansailor for trying to dig into and explain Gonzo's thinking to me.

 

They need to either stop demanding a canoe or lower the target speed.

 

Has anything been said about budget for the project? For example, with an unlimited budget, you can use other methods to achieve those goals, with or without boats.. "With the dollar, dance the doggy, haha!"

 

Gonzo and Skyak have lots of good points.

The way to deal with this is to return to the end user and reset expectations based on some rudimentary understanding of the pros and cons and limits to various metbods and boat designs.

Absent setting expectations, people will end up disappointed.

The way this can be done nicely is with a decision tree and some explanations.

 

Yes, that it is really low.

 

Yes, but starting with a torquedo is not exactly cheap, (or necessarily the most efficient,) there are other brands and lower cost methods that might well be better, JMHO. The 40 horsepower would be very heavy with batteries; Maybe too expensive to run at 11 knots for 2 hours, if someone is on a "shoestring" budget post # 16. Many years ago in my experimentation, I got an Asian long tail kit for well less than $100, Sans motor, and easily mounted a large efficient Surplus PM electric motor, ran it for a few months just to get some data, and for grins, haha!

From OP #14, "My aim here is to confirm that electric is unfeasible and to have a good justification to bring to the user." Lots of information in the above postings by various members that will help you with this.

How much do the current dugouts cost to build and run, and is the goal to get below that, or how much dollar leeway do you have, above that?

If your budget allows it, you can buy a torquedo and run the dugout just to get an idea about performance and costs as a comparison to the fiberglass alternative? Maybe somewhere in Ecuador there is a large 10+ sculling shell that can be begged, borrowed, or rented for a comparison of speed and efficiency to the dugout, when powered buy a torquedo? Just some out of the box ideas, FWIW...

 

torqeedo is a terrible company who does not support repairing their product, probably not a good idea. Furthermore, they are not even engineered for this and the cost is too high anyway.

Second point: several users here are biased against electric power, so keep this in mind. They seem to have a limited understanding of it without any first-hand experience. Some are very pro-combustion engine with many comments regarding burning fossil fuels. You can search the forum to confirm this. So if someone concludes electric is not feasible, it is because they always concludes this for every possible scenario without ever trying it themselves.

By contrast, I have traveled all over the world without ever using any fuel, and I have a 50 year old boat which can achieve 20 knots of speed under sail, though I generally sail 12 knots and less. I have used electric propulsion and my only charge source is solar panels and hydro generator. I built an electric propulsion for it using $100 ebike motor that can power 3 knots using 300 watts. This is < 0.5 horse power. My boat is 10 meters long.

electric is feasible. Furthermore, in fast moving waters, it is possible to recharge the battery when not in use and/or to use solar panels for recharge.

As for using 40 horse power: this is a ridiculous amount of power and not needed. It will make the cost and weight very high too.


I would suggest you increase the length of the boat to 15 meter and decrease speed to 8 knots and consider sails. As noted elsewhere, it is possible for a boat to sail faster than the current or make progress against a current with absolutely no wind. This is not different from a vmg faster than the wind downwind.

If the power required is within reason, only a few kw will do. Pay close attention to propeller. High aspect ratio larger diameter gives a better efficiency but requires more reduction gears and may be less durable (thin carbon blades) if you are using on rivers with rocks, I dont know all the requirements.

for traversing very fast rapids (if this is the 11 knot requirement) it may make sense to shoot an anchor with something like cross bow, and then winch the boat forward using this. It will achieve a far higher efficiency than pushing on the water with a propeller. In fact, the efficiency will be very good going against rapids and eliminate any speed requirement.

 

Sailing in a meandering river with tall trees on the shores is not feasible.
As far as electric power, it is not possible to install it on a canoe of the dimensions required by the client and fulfill the target range and speed. Gasoline and diesel are more energy dense than batteries. Also, it is faster to fill a tank than to recharge a battery.
Shooting anchors with a cross bow works in James Bond movies; in real life not so much.

 

Can above water or underwater current sails be used where low draft and significant debris are a consideration? Also, It might not be possible to maintain 11 knots using the stop and go winch / crossbow method? Solar generation and Tow generators contributions might be diminished because of shading, low draft, and moving/floating/stationary debris. JMHO. That said, I have been using only Electric Power propulsion for at least four decades in my Niche applications, with dozens of different boats, and consider myself a proponent of battery electric motors...

 

What is an "underwater current sail"?

 

From post # 37
"As noted elsewhere, it is possible for a boat to sail faster than the current or make progress against a current with absolutely no wind. This is not different from a vmg faster than the wind downwind." What I wrote may not be the official name for this type of propulsion, haha!

Sailing Without Wind. https://www.boatdesign.net/threads/sailing-without-wind.67181/

 

Target speed is 11Kt VMG. I think the OP got tired of unrealistic ideas.

 

I have done this in my own boats, looking up often to avoid hitting tree branches.

And this is to reach recently un-contacted people. I am sure they have an 11 knot requirement and always used combustion engines for thousands of years in this area.

you are only proving my point that you are biased against electric. I think we all know you have zero experience using electric propulsion. I have zero experience using combustion engines, because as far as I am concerned the fact they consume fuel is a non-starter.

Shooting anchors out and winching them in is far and away the most efficient way to power a boat against a strong current. This could also include an electric RC boat/anchor that drives ahead then sets in the bottom or any of several methods.

 

The Stop and Go process of shooting out anchors and winching might be much faster and more efficient if it was employed in in a fashion similar to the cable and rope tows used by skiers? The basic idea is a very old concept used with Canal boats,



If the OP's distance is the same 2 km it might be doable, if it is a clear and straight section or if there's enough funding so that it can be made into one? Maybe another way is to lay a cable or rail underwater (San Francisco cable cars concept) but have an on board motor do the pulling? So, it can also be done without using boats, haha...

 

Please stop with your personal attacks. I have worked in battery research for several years. First at the Johnson Controls labs and for Dr Deyang Qu at UW Milwaukee. There is no bias on my part against electric systems. I am, however, an engineer and know the limitations of those systems. I don't know where you get the idea that this is to reach uncontacted people. It is a tourist attraction for "eco-tourism". The OP was asking intelligent, concise questions. This thread deviated from what he needs into rants and far-fetched ideas that have no connection to technology. The question was for a 30 foot canoe with a target speed of 11 knots.