Electric Propulsion

[jkleins]

Originally Posted by daddle

...And the slick claims without independent unbiased evidence, and little engineering basis, haven't impressed me either.

Because we always have such good independent, unbiased evidence on which to base all our other cruising equipment purchases?

Jim

[daddle]

Originally Posted by jkleins

Because we always have such good independent, unbiased evidence on which to base all our other cruising equipment purchases?

Well.....the 58hp diesel in this thread very likely produces a legit 58hp when installed per the datasheet. And it likely burns fuel at the rate specified. And it will likely run for the expected lifetime. We can trust the claims. The burden is on the electric promotors to come up with equally trustworthy specifications. As a skeptical engineer (who can read between the numbers) I have not seen any such specification from the electric proponents. Just vague claims and informal unsupported testimonials. Yes, I'm picky.

[DeepFrz]

If you open up the throttle on your 60 hp diesel, you will burn 3 gal/hr, or $12-15/hr at current prices.

Almost no one runs their diesel at WOT for an hr. You are probably looking at cruising at 4 to 5 liters per hr. (or less) in most cases.

Boats and yachts do not.

I would disagree on this one. Only the go fast planing cruisers and semi-displacement boys in a hurry operate at anywhere full power. Manny semi-displacement boat drivers have learned to cut their power way back and cruise at displacement speeds in order to save fuel. But even at these power settings, as I mentioned before, Nordhavn and one buyer spent a lot of money trying to get diesel electric to work properly/efficiently on a yacht. I don't know all the details but I do know that it didn't work out very well.

Not sure about Nigel Calder. Is he still pressing forward with a hybrid boat?

[DeepFrz]

Something else. We have to be careful when we claim that things work or don't work and whether they are cheaper or more expensive. A lot depends on the mission and the gear. Cost will depend a great deal on quality and mission. For instance, an analogy, you can buy an electric fan for $12. and you can buy an industrial quality electric fan for hundreds of dollars. I would think the same would go for electric motors used in marine drive lines (scaled up of course).

[fastcat435]

Originally Posted by DeepFrz

Something else. We have to be careful when we claim that things work or don't work and whether they are cheaper or more expensive. A lot depends on the mission and the gear. Cost will depend a great deal on quality and mission. For instance, an analogy, you can buy an electric fan for $12. and you can buy an industrial quality electric fan for hundreds of dollars. I would think the same would go for electric motors used in marine drive lines (scaled up of course).

Yes Nigel Calder is still working and improving his electric drive system in his Malö 46 trying out different solutions , motors , controllers etc.

Regarding cost, purchasing off the shelf products or developing and producing a specific product ( motor) for a yacht has huge cost consequences.
Same goes for the batteries that make up a large portion of the cost, having AGM or Lithium is 1 : 10 in price for the same available power .

[fastcat435]

Originally Posted by Dan_78

The propellors going up and down is automated through reading the battery voltage? Looks like a pretty nice system. Should make those worried about drag a bit happier.

Hallo Dan
They do not go up automatic , however they go in to free spinning mode once the batteries are full, and give a audible signal. We lower or raise the Motogen's with switches.
While cruising if we need the energy we normally lower one unit and get ( speed depending )
between 500 watt ( 6 knots ) and 3 Kw power out. ( 13 Knots )
These are 10 Kw Motogen's * motors / generators

[smallyachts]

I sure would like to hear from some of the old diesel boat (submarine) folks.

They ran diesel electrics in those boats during WWII.

I served on board nuclear boats. That is a hybrid system as well.

I have also been onboard a number of large transport vessels that ran quite happily in a diesel electric scenario.

I believe I saw an article where a couple of the new cruise lines have adapted to that as well.

A well designed hybrid system should work quite well.

Yes, you may have to listen to the genset when you need more range than the battery bank provides, but you won't have to listen to it all the time.

[barnakiel]

Originally Posted by geckosenator

(...)

Electric is _not_ more expensive. Etek motors cost a fraction of a diesel with the same power.

(...)

...but with electric you can recharge your batteries under way, and motor forever on solar power. With diesel you run out of fuel, and correct me if I am wrong, but you cannot produce diesel fuel under way.

(...)

Everyone I see using diesel could have gone electric for less money, and still used it the same way they are using the diesel.

Hi,

Re 'electric is not more expensive'. I will disagree. Once the cost of the batteries and the cost of a genset is chucked in, and I do not see any alternative for a genset if I want to use the el propulsion a) at any time and b) for extended periods.

Re 'recharge under way'. I would say sometimes you can and at other times not. A boat becalmed on an overcast day is but one example.

Re 'everyone...for less money'. I cannot. I have considered / researched a small electric and it is cheaper for our configuration to go for a small diesel engine.

I think el propulsion is a great solution for some right now and it has great future potential as the components will improve, but as is, it is not an alternative for many cruisers.

Cheers,
b.

[GordMay]

Originally Posted by fastcat435

Yes Nigel Calder is still working and improving his electric drive system in his Malö 46 trying out different solutions , motors , controllers etc...

The "Nada" Project (Blog) by Nigel Calder
Last updated on 11/29/2010 ➥ Blog

An article, from 2008, about Calder’s new hi-tech boat
➥ On the Leading Edge

[goboatingnow]

its funny Calders Blog, stopped being updated

Dave

[skipmac]

Originally Posted by barnakiel

Hi,

Re 'electric is not more expensive'. I will disagree. Once the cost of the batteries and the cost of a genset is chucked in, and I do not see any alternative for a genset if I want to use the el propulsion a) at any time and b) for extended periods.

Re 'recharge under way'. I would say sometimes you can and at other times not. A boat becalmed on an overcast day is but one example.

Re 'everyone...for less money'. I cannot. I have considered / researched a small electric and it is cheaper for our configuration to go for a small diesel engine.

I think el propulsion is a great solution for some right now and it has great future potential as the components will improve, but as is, it is not an alternative for many cruisers.

Cheers,
b.

In a nutshell that is pretty much my conclusion.

[DeepFrz]

I don't think Calder has stopped updating his blog he just hasn't updated it for a while. Looks to me, from an uninformed distance and going solely from the info in his blog, like they still have a ways to go to put it all together in a boat. It also looks like all yachts may reap benefits from the research being done for the project, especially propeller research.

[Dick Pluta]

As prelude to my remarks I offer this quote from my favorite president, Abraham Lincoln, who said in his Gettysburg address:

"The world will little note, nor long remember what we say here"

I think that's a good thing...maybe.

I just started reading this thread and I am, as always in these cases, amazed at the amount of information and disinformation presented. For you guys who don't understand torque, try this. Take an old washing machine motor and hold the shaft as tight as you can. Have your wife plug it in and try to keep it at 0 RPM. Let me know what happens. It's not for nothing that the Tesla sports car is one of the fastest cars in the world.

Anyway, that said, electric drives are extremely well developed and have been for over a century. Railroad locomotives, both electric and diesel-electric, have been operating for many decades. Some of the first cars were electrics. Because of environmental issues there are electric boats operating on some lakes in Germany that go all day on a charge. Need I mention submarines? Does electric propulsion work? Of course it does. Does it have all the advantages its proponents claim? Of course it does. There are only two important questions about electric propulsion. First, where do you get the electricity and second, where do you keep it?

Let's answer the second question first. In the context of this discussion, we first need to define how much electricity we're talking about. Based on the numbers offered by EAS about his 48v electric system:

Estimated speed/power numbers. The boat will motor at 2-3Knots (10Amp draw) 3-4Knots (20amp draw) 4-5knots (35A) 5-6 knots (50A) 7knot hull speed (75A)

Assuming 5-6 knots cruise, we can now estimate required daily power consumption for this boat as follows:

50A x 48V x 24 hours = 57,600 Watt-hours or 57.6 KWH required to cruise continuously for 24 hours.

That's 48 100 amp hour 12v batteries (57600 Watt Hours/12V = 4800 Amp Hours, 4800AH/100 AH per battery = 48 batteries). Of course, that's pure electric and you can use fewer if you want less time under power. For 1 hour, divide all numbers by 24. 1 hour, 2 batteries.

Now, where do you get it. First solar. If you use a 240W panel mentioned by KEALOHA, that's 10 panels operating continuously, 24 hours, at full output. Do solar panels work in the dark? No? Make that 20 or 30 panels. Maybe more on a cloudy day. Wind? If you've got wind you don't need the motor. Regeneration? Certainly extends range but unless you've got a generator that makes more than it uses, that begs the question of where you get the power from if you're out of it for whatever reason. You're that long distance cruiser operating out of sight of land for days or weeks? I guess that leaves out stopping at a marina. Oh, you're coastal hopping? Well, I think a marina might look at you in a funny way if you asked for a connection big enough to recharge all those batteries overnight. Well, I guess that takes us back to an on board generator, which is what we were trying to avoid in the first place.

So, in the end, it boils down to what you want to do. Going in and out of harbor? Absolutely doable. Long distance cruising with lots of time to recharge and limited range? Certainly, if you willing to risk a few days sitting still while your solar panels do their thing. Your wind generator and regeneration system, of course, don't work if you have no wind and aren't moving.

Until someone comes up with a revolution in charging systems and batteries I'm afraid most of us just aren't candidates. I saw a lot of the US electric car programs from the inside and you wouldn't believe what they have tried to make lightweight, high power batteries. Would you believe liquid sodium at 500 degrees F? I don't want to take that one through a car wash. How about bromine? Yeah, that's right, a first cousin to that poison gas, chlorine. Batteries just aren't there just yet. Jay Leno has a 1909 Baker Electric car in his collection. Here's what he says:

"I'm not too bullish on electric cars as the way of the future. Modern electric cars go roughly 100 miles on a charge, about the same as my Baker; so I don't see much progress there. I think electricity is a great power source for a car. But the problem is, how do you get it?

Thomas Edison invented the alkaline battery. My Baker still has some original alkaline batteries. These have lead plates and use acid; we wash them out and refill them regularly and I'll use them indefinitely. But even Edison realized the future of the automobile was elsewhere. Legend has it that back in 1896, at a dinner party, he passed a note to his friend Henry Ford. Essentially it said, "The electric car (boat?) is dead."
How prophetic was that?"

Personally, I've gone down the ICW several times in my 41' sailboat and, sad but true, most of it was under power. Unless you can tell me how to put 8 to 10 hours "in the tank" overnight, electric just doesn't work for me. It's got nothing to do with electric. I love the idea but, like electric cars, the practical applications, like commuter cars, are limited and the disadvantages too great for most of us. I don't relish the idea of calling the boss on a Sunday night to tell him (or her) I can't make it to work because I'm sitting offshore in a dead calm with no motor. Oh, wait! I'm retired. Screw the boss. Where can I get one of those electric thingies?

Dick Pluta
AEGEA

[LauderBoy]

Originally Posted by daddle

Well.....the 58hp diesel in this thread very likely produces a legit 58hp when installed per the datasheet. And it likely burns fuel at the rate specified.

Yeah, but it really doesn't. Let's look at a 4JH3E which is rated at 55.3HP(41.25kW).

http://www.simplicity-marine.com/pdf/Yanmar/JH.pdf

It's peak HP is 56(41kW) at 3800 rpms.
But it's continuous HP rating is only 50(37kW) at 3650 rpms.

However you don't want to operate the engine even at the continuous rpm level all the time. Yanmar recommends that this engine run at 3000 rpm: Yanmar Marine Engine Help

That's 48HP(34kW) for the 3000 rpm level.

The above isn't shaft power, it's brake HP. You'll lose about 4% of the above powering pumps, the alternator, the transmission, etc so you might only be getting 46HP. But still, that's pretty good.

But really when you move the throttle to 3000 rpm you're not actually running at 48HP. Look at the prop power curve. At cruise speed the prop is asking for 28HP(20kW). So the engine responds by giving it 28HP even though it has the potential for 48HP.

So at 3000 rpm your 55HP engine is putting out around 28HP.

The prop power curve is very boat dependent. It depends on hull efficiency, prop size, current conditions and so on. Typically the designers try to meet the prop curve and the engine HP curve at the peak of the engine.

Also, one thing about the yanmar chart is it starts at 1850 rpms. That's probably because the engine doesn't start putting out any real power until that point.

An electric engine power "curve" is a flat line going up at 45 degrees that starts at 0 rpm: http://www.ngcmarine.com/pdf/techcornergraphics.pdf

This allows for a "weaker" 8.5kW electric engine to meet the prop power demand up to cruise speed even though it's about half the "power" of the 15kW 20HP diesel engine. The diesel may perform better in the higher rpms, but the electric stomps all over it in low rpm band. This gives electric that "instant power" feeling and may let you do things like have your engine provide a small "push" while under sail to reach higher speeds.

But I'd really like to know is how the electric engine performs past that cruise speed point. I wonder if it'd give you that "that's all she's got Captain" feeling more so than the diesel.

[David M]

The primary problem is that the energy density (Stored energy per amount of weight) of Diesel is still much greater by many factors than the most efficient batteries. Were this not the case then we would have battery powered commercial aircraft.


Since boats are sensitive to weight and there is no way around this fact, then batteries will have to become much lighter per amount of energy stored, and not physically larger either, if it is ever going to compete equally with Diesel.