Electric Outboard Motor

[offpist]

Thanks Mark.
At full throttle we are talking 30 minutes @ 24KM/H.
For a really long trip i can bring both batteries for double capacity.

At 6KM/H it uses about 600W with 3 persons on board, so that should give us 6 hours on one battery.. 12 hours on two. This is theoretic as I have never tried to run it long enough to out of battery.

Connection it to the charger on board is easy, but we dont charge after every trip. One charge lasts many day trips.

[Electric Ray]

Fantastic, you are inspirational,I have been trawling this site looking for real, not marketeer experience of this tech, but most are negative. I was hoping to find feedback on aquawatt 13kw outboards as this is the best fit for my present systems, and there is no way I am putting 350v on a saltwater boat, unfortunately it looks like I might have to look elsewhere for that feedback. Keep up the good work/play, regards, Mark

[myocean]

Originally Posted by valhalla360

Talk about more efficient props and torque at RPM, is pure marketing. If they could achieve enough improvement to be noticeable they would put them into production on traditional outboards.
- It violates the laws of physics to claim a 30hp electric motor will outrun a 30hp gas motor at top speed, HP is HP,

No, sorry - I think you are wrong about this! There seem to be huge losses in the conventional systems!
Like you can see with all the electric cars as well, they have a very different characteristics as the torque at low speed is much higher. It is the same in the water. With an electric drive you can have a prop which generates more thrust already at low rotational speeds.
Additionally the mechanical efficiency (the drive train and the prop) of combustion outboards is very low, because scarce energy has never been an issue for the manufacturer - and saving money in production is more important for them than saving energy.
Torqeedo has described this very well on this page:
Performance & Efficiency - Torqeedo

Consequently, same as for energy efficient LED light bulbs, you can not just talk anymore just about the power a device has.
A rating showing the EQUIVALENT power of an 'old style' system, just for comparison, is required.

[valhalla360]

Originally Posted by myocean

No, sorry - I think you are wrong about this! There seem to be huge losses in the conventional systems!
Like you can see with all the electric cars as well, they have a very different characteristics as the torque at low speed is much higher. It is the same in the water. With an electric drive you can have a prop which generates more thrust already at low rotational speeds.
Additionally the mechanical efficiency (the drive train and the prop) of combustion outboards is very low, because scarce energy has never been an issue for the manufacturer - and saving money in production is more important for them than saving energy.
Torqeedo has described this very well on this page:
Performance & Efficiency - Torqeedo

Consequently, same as for energy efficient LED light bulbs, you can not just talk anymore just about the power a device has.
A rating showing the EQUIVALENT power of an 'old style' system, just for comparison, is required.

Electric cars have totally different performance requirements that do favor the low end torque of electric motors.

60-70hp is plenty to keep a compact car doing 75mph on a freeway uphill or into a good headwind but the limited torque at low RPM will make it a total slug in city driving. The solution for peppy performance is to drop a 100-150hp engine to get more low end torque and to give decent city driving performance but it's way overpowered on the freeway.

A displacement cruising boat typically cruises at a steady 6-7kts and acceleration is just not a big concern. No one cares if 0-6kts is 10 seconds or 20 seconds if you are going to accelerate to 6kts and leave it there for the next 5hrs. In a docking situation, I've never used full throttle and even so, a prop is different as slippage allows the motor to get up to speed before the boat starts to actually move. Unlike a car where during normal operation, the wheels don't turn faster unless the car is going faster. For a cruising boat, the motor is sized to match cruising speed at ideal effiency with a little extra power left over for fighting a strong headwind or waves. A reduction gear provided so you can turn the prop that best fits the boat (not that all manufacturers spend the time matching the prop to the hull).

In theoretical terms, electric is more efficient. For every kwh of energy in storage on an electric boat, you will turn a higher percentage of it into forward thrust but storing electric power requires orders of magnitude more space so the minor efficiency advantages are outweighed many times over by the drastic reduction in energy storage space required by diesel.

Now if you are building a ferry that rarely does more than a 1/4-1/2 mile between stops, the low end thrust of an electric motor might come in handy because you are constantly accelerating and decelerating the boat but for a typical cruising boat application, the low end torque of an electric motor is very rarely of benefit.

Not sure why you are talking about light bulbs. Other than the odd kerosene lantern used by someone who just wants one because they think it's cool, no one is suggesting a petrol powered lighting system.

[myocean]

Sorry, that I did not manage to explain this in a simpler way.
Why compare this with the situation in the light bulb market? It's just the same thing: Efficiency is nowadays much higher with the new technologies which is why the power ratings of the old fashioned products (such as outboards with a very conventional drive train) can not directly be compared with the power ratings of the new technology products.
I think the information about this which is provided by Torqeedo (see link above) is probably quite correct!
Sure, storing electric energy is still quite a challenge. That's why the whole world is working on improvements. But there are already today applications (for boats in the same way as for cars) where electric power is the better solution or is just more fun.

[myocean]

Oh, and one more thing about higher torque at low revolutions: this just means you can operate with lower rpm for the same speed in the water IF you design the prop accordingly. So because of this too it's difficult to do a direct comparison with normal combustion engines.

[valhalla360]

Originally Posted by myocean

Sorry, that I did not manage to explain this in a simpler way.
Why compare this with the situation in the light bulb market? It's just the same thing: Efficiency is nowadays much higher with the new technologies which is why the power ratings of the old fashioned products (such as outboards with a very conventional drive train) can not directly be compared with the power ratings of the new technology products.
I think the information about this which is provided by Torqeedo (see link above) is probably quite correct!
Sure, storing electric energy is still quite a challenge. That's why the whole world is working on improvements. But there are already today applications (for boats in the same way as for cars) where electric power is the better solution or is just more fun.

Incandesant vs LED use the same power source so efficiency provides a direct benefit.

Electric motor vs Diesel motor use totally different power sources, so the massively more dense fuel source easily outweighs the minor efficiency improvements.

The "whole world working on improvements" is mostly media articles and accepting reduced performance (mostly range related).

[valhalla360]

Originally Posted by myocean

Oh, and one more thing about higher torque at low revolutions: this just means you can operate with lower rpm for the same speed in the water IF you design the prop accordingly. So because of this too it's difficult to do a direct comparison with normal combustion engines.

Pick your ideal prop and you can do the same thing with a diesel and a reduction gear.

Yes, a large prop is more efficient but it's hull design that typically limits prop size not the ability to turn it.

[uncle stinkybob]

I'm on a budget. For what it cost to set up for running electric propulsion, the unit itself, battery's, charging system's, maintenance, I can buy enough fuel, pay for all maintenance, rebuild the motor at least once, for the rest of my life. I like green but not at the cost of whats offered at present. When these systems can compete with the cost of of present diesel propulsion, it's not even a consideration. I do appreciate the folks who can and do afford these electric systems, you are the ones paying the big money to be the test beds for the development.

[Ribbit]

It's not just the energy density issue with batteries vs diesel.

There's the inescapable reality that diesel doesn't have to carry its own oxygen supply, which batteries do.

Ultimately there is no way that electrical storage can truly compete, unless it is a fuel cell system that doesn't have to carry its own oxygen.

Liquid energy storage didn't come to dominate because it was a bad idea. Quite the reverse.

Better to go the route of ultra clean synthetic diesel, imho (cheap enough via Plasma Gasification and associated Syngas production).

It's current tech (getting more and more efficient), and it actually works at reasonable prices.

[Bill Seal]

It's not just the energy density issue with batteries vs diesel.
There's the inescapable reality that diesel doesn't have to carry its own oxygen supply, which batteries do

Congratulations! You're the one person in 10,000 who understands the physics of propulsion systems. About 3/4 of the energy in a Diesel or Gasoline engine comes in through the air cleaner.

[Electric Ray]

Originally Posted by myocean

Oh, and one more thing about higher torque at low revolutions: this just means you can operate with lower rpm for the same speed in the water IF you design the prop accordingly. So because of this too it's difficult to do a direct comparison with normal combustion engines.

Hi My Ocean

Do you know of any manufacturer that is actually shipping a 50v high power outboard in the range of 20hp? so far all I seem to come across are vapor ware with no real customers willing to talk about them and flat earthers who think diesel will last for ever.

To all those flat earthers, keep sailing to horizon.

Mark

[myocean]

Originally Posted by Electric Ray

Do you know of any manufacturer that is actually shipping a 50v high power outboard in the range of 20hp?

Hi Mark! You mean 50 Volt? 20 HP?
I don't really know all the smaller players and I am not the electric drives expert. I just find this subject interesting. I see Torqeedo has this 48 V model cruise 10.0 which can, they say, replace a 20 HP outboard with just 5.6 kW.
See Outboard - Cruise 10.0 R - Torqeedo

And then there are the 350 V models, probably more for professional users.
The Deep Blue 40T can replace a 40 HP outboard with just 16 kW. Prices are a bit like Tesla prices, but seem still to make sense for some professional users and people who just love this.
See Outboard - Deep Blue 40 TXL - Torqeedo

Ulf

[StuM]

Originally Posted by myocean

Hi Mark! You mean 50 Volt? 20 HP?
I don't really know all the smaller players and I am not the electric drives expert. I just find this subject interesting. I see Torqeedo has this 48 V model cruise 10.0 which can, they say, replace a 20 HP outboard with just 5.6 kW.
See Outboard - Cruise 10.0 R - Torqeedo

Same old crafty advertising wording.

"The Cruise 10.0 is comparable to a 20 HP petrol outboard "

A tack hammer is comparable to a sledgehammer - but one won't replace the other.

"12 kW peak power, 10 kW continuous power – powerful propulsion like a 20 HP combustion engine"

"like a 20HP combustion engine" in what way.

At 0 RPM? Is it like an 20HP combustion engine at max continuous RPM?

Oh, and that page says 12/10kW not 5.6.

[myocean]

Originally Posted by StuM

Oh, and that page says 12/10kW not 5.6.

Oh yes, I see, sorry! The right kW numbers for input power are 25 kW and 10 kW. Somehow, for both motors, I just read the numbers for "propulsive power" in the specifications tab, not the electric "input power. As I understand they say this "propulsive power" is more or less identical to what a traditional outboard manages to generate in the water.

To check, if this is all real, the best would probably be to try such an outboard. I don't know if that is possible on some boat shows or if the dealers offer such trials?