Electric Propulsion on Catamarans

[44'cruisingcat]

2240 Watts vs 7400.....

And you did notice that the difference in props was only 1 inch? 10%? Whereas the difference in max rpm was closer to 100%...

And I seriously doubt the Yam 9.9 HT would stall with a 12x10 prop. In fact I wouldn't be surprised if 12 x 10's were available.

You're right though, Torqeedo's are overpriced. I'd be surprised if it cost them more than $500 to make one. There's more engineering and materials in a normal outboard's gearbox, than the entire Torqeedo motor.

[deckofficer]

Originally Posted by 44'cruisingcat

2240 Watts vs 7400.....

And you did notice that the difference in props was only 1 inch? 10%? Whereas the difference in max rpm was closer to 100%...

And I seriously doubt the Yam 9.9 HT would stall with a 12x10 prop. In fact I wouldn't be surprised if 12 x 10's were available.

You're right though, Torqeedo's are overpriced. I'd be surprised if it cost them more than $500 to make one. There's more engineering and materials in a normal outboard's gearbox, than the entire Torqeedo motor.

1" higher pitch isn't going to stall the 9.9.

There is more engineering that goes into electric motor design than you might think. On a typical 100 hp electric motor used on the ships I served on for pumping, they were air cooled, ran on 480 VAC and stood 3' tall weighing 500 lbs. On the oil exploration rigs I served on that had a ROV, it too had a 100 hp electric motor that weighed about 80 lbs in a much smaller footprint. It uses rare earth magnets, the umbilical cord fed it 5000 volts, and it was cooled by being heat sinked into the water medium. What Torqeedo has done, since they are using a low voltage of 48 VDC is to of course also heat sink into the water medium and to reduce drag they kept the footprint small by running at a high rpm into a planetary gear set for reduction to the prop.

I have looked at other electric outboards and none have the efficiency of that expensive German offering.

[Blue Skye]

Disclaimer: yep, I'm a dreamer

I believe all electric is very close. I also believe if one is accepting of the limitations it currently presents that it is viable. How many cruisers get to an area and leave the next day to motor for 8-9 hrs? I know it happens, but I would think it's very possible for caribbean and even south pacific cruising/exploring as long as one isn't trying to circumnavigate or cross oceans in 6 months. I've read over and over the multiple threads on the electrical pros and cons, but there are several examples I've read that are doing it. 44Cs cat would (IMO) be a perfect boat to go all electric. Lightweight and sails in light winds. On the other hand, lagoon, FP, leopards and other heavy production boats are not ready for this technology. Having said that, its a matter of time that we will be fossil free. Its adaptation, we have to figure it out. I applaud those who are pushing the technology while understanding those who say it's not ready... oh did i mention i'm a dreamer? Build it and they will come

[deckofficer]

Skye,

Since you came clean and said your a dreamer, I'll come clean and admit it is a religion for me. Having worked for Noble Drilling in offshore exploration, I want to see the whole world get off the fossil fuel addiction.

[Stumble]

Originally Posted by deckofficer

Greg,

What part of the Atlantic 21 are you having a hard time wrapping your mind around?

Just this... The Atlantic 21 took 90 days to travel about 7000miles and averaged ~3.25nm over the course. As part of the record setting they wisely stayed in the Northern Equatorial Current, and timed it for when the current is at its strongest. But this added about 1kn to their SOG. meaning the electrical power was able to get them to an average speed of ~2.25 knots.

They used a heavy cat, because light weight cats aren't capable of the load carrying needed to handle the batteries. And frankly at these speeds the power demands between a lightweight hull and a heavy hull probably aren't that great.

As I keep saying if you are ok with an average speed of 2.25kn fine, go electric. It's been proven to work, and within these parameters it will work well. But even a moderately sailed boat will far exceed this as an average on an ocean crossing. Pure electric is simply slower and more expensive than sails.


On another note, where are you getting a 6lb, 20% efficient, 150 watt solar panels?

[44'cruisingcat]

Originally Posted by deckofficer

1" higher pitch isn't going to stall the 9.9.

There is more engineering that goes into electric motor design than you might think. On a typical 100 hp electric motor used on the ships I served on for pumping, they were air cooled, ran on 480 VAC and stood 3' tall weighing 500 lbs. On the oil exploration rigs I served on that had a ROV, it too had a 100 hp electric motor that weighed about 80 lbs in a much smaller footprint. It uses rare earth magnets, the umbilical cord fed it 5000 volts, and it was cooled by being heat sinked into the water medium. What Torqeedo has done, since they are using a low voltage of 48 VDC is to of course also heat sink into the water medium and to reduce drag they kept the footprint small by running at a high rpm into a planetary gear set for reduction to the prop.

I have looked at other electric outboards and none have the efficiency of that expensive German offering.

I'm not saying it can't be done, or that it won't work. All I've been saying is that Torqeedo is being highly optimistic when it says the cruise 4 matches a 10 hp outboard. It doesn't.

Especially when you throw in the fact that the 10 hp motor comes with a 10 litre fuel tank, which will run it for around 10 hours... you need batteries of 1000 USABLE amp hours at 48 volts to match that.

But yes, I do think an all solar/electric boat could be done. But if you want to exclusively use electricity for refrigeration, watermaking, cooking and heating water, as well as propulsion, you're going to need a very large solar array. I'd be thinking around 4 - 5 kW. And lots of batteries.

[deckofficer]

Originally Posted by Stumble

On another note, where are you getting a 6lb, 20% efficient, 150 watt solar panels?

EVTV Motor Verks Store: Flexible Solar Panel 180w, Solar and Boat, 180wsolarpanel

[downunder]

Originally Posted by Blue Skye

Disclaimer: yep, I'm a dreamer

I believe all electric is very close. I also believe if one is accepting of the limitations it currently presents that it is viable. How many cruisers get to an area and leave the next day to motor for 8-9 hrs? I know it happens, but I would think it's very possible for caribbean and even south pacific cruising/exploring as long as one isn't trying to circumnavigate or cross oceans in 6 months. I've read over and over the multiple threads on the electrical pros and cons, but there are several examples I've read that are doing it. 44Cs cat would (IMO) be a perfect boat to go all electric. Lightweight and sails in light winds. On the other hand, lagoon, FP, leopards and other heavy production boats are not ready for this technology. Having said that, its a matter of time that we will be fossil free. Its adaptation, we have to figure it out. I applaud those who are pushing the technology while understanding those who say it's not ready... oh did i mention i'm a dreamer? Build it and they will come

The Torquedo deep blue inboard or outboard would be necessary propel a cat the size of 44C's vessel but at considerable more cost than the cruise 4.0 outboards.

Torqeedo Deep Blue, electric outboard, Boats using large electric motors

The Cruise 4.0 series have been tried unsuccessfully in Australia and 44C has had considerable feedback and real observation with them. perhaps OK on dingys.

Cheers

[mrm]

Originally Posted by deckofficer

EVTV Motor Verks Store: Flexible Solar Panel 180w, Solar and Boat, 180wsolarpanel

Sadly, their marketing is overly optimistic. Let's see... using data from above link:

Length: 1302 mm / 51.26 inches
Width: 796 mm / 31.34 inches
[...]
Max Power: 32.92v @ 5.45 amps

So:

Max power = 32.92 [V] * 5.45 [A] = 179.414 [W]
Area = 1.302 [m] * 0.796 [m] = 1.036392 [m2]

yield from 1m2 = 179.414 [W] / 1.036392 [m2] = 173,114 [W/m2]

panel efficiency = 173,114 [W/m2] / 1000 [W/m2] = 17.3%

Decent, but not superb.

[Blue Skye]

Originally Posted by downunder

The Torquedo deep blue inboard or outboard would be necessary propel a cat the size of 44C's vessel but at considerable more cost than the cruise 4.0 outboards.

Torqeedo Deep Blue, electric outboard, Boats using large electric motors

The Cruise 4.0 series have been tried unsuccessfully in Australia and 44C has had considerable feedback and real observation with them. perhaps OK on dingys.

Cheers

Yea, was speaking more in general. Torqeedo is very expensive and limited IMO. Something like Biankas system but used with LiFePO4 seems quite possible in a lightweight cat that sails well. I've been a power boater my entire life and love the idea of a sailboat with no gas/diesel onboard

[nimblemotors]

So we all agree Torqueedo is over-priced and over-optimistic

There would no particular good reason to use an undersized electric motor because unlike a fuel engine, you can run them slow or fast with little loss of efficiency. The extra cost is mostly in the motor controller to handle higher power, but I'd rather have that available that not.

I'm putting the electric motor below in my Porsche Boxster right now,
the big one on the left.
The one on the right is the main drive motor from a Prius.
The one in the middle is the 'mars bldc or etek' motor similiar to the one in bianka's

[deckofficer]

Etek, tough little motor though not near as powerful as your Porsche would require. What are the specs on the motor going into the Porsche? What batteries and controller are you going to use?

[nimblemotors]

I don't want to start a discussion of my CAR project, but motor is a 9in ADC I am making my own motor controller, and will be testing out ideas with a big capacitor bank and a pretty small A123 lithium pack.
More of a race car really, monster acceleration..I hope.

Originally Posted by deckofficer

Etek, tough little motor though not near as powerful as your Porsche would require. What are the specs on the motor going into the Porsche? What batteries and controller are you going to use?

[deckofficer]

The A123 can crank out the amps. You going to compete? Take out John Wayland's White Zombie?

[nimblemotors]

Originally Posted by deckofficer

The A123 can crank out the amps. You going to compete? Take out John Wayland's White Zombie?

No NEDRA racing for me. Just testing out the supercap design.