diesel/electric hybrid

[sandy daugherty]

We all would benefit from studying Nigel Calder's articles in Professional Boat Builder. Although he is pretty firmly opinionated, his research is thorough and acurately presented. He is not particularly impressed with the possibilities of regeneration, but I found his information on single rail diesel generator and particularly efficient propulsion motors a bit startling. It could be better than conventional propulsion systems in terms of reliabilty and efficiency already, and cheaper in the long run at current fuel prices, for both power and sail. But its just not there yet for my foreseeable budget.
I spent several hours maneuvering the Solomons powered 47' catamaran after the boat show">Annapolis Boat Show several years ago, and was absolutely blown away with the ease of maneuvering with smooth little levers that commanded smooth little power changes without crashing thru gears or choking on clouds of diesel exhaust. No drama, just good seamanship. I imagine the Lagoon 420 is at least as remarkable. Outremer has a similar system in their 44(?) hybrid. I'm leaving that suggestion under my pillow for the tooth fairy to find.

[henryv]

gosstyla - I agree that you need a genset or other power source however it still seems to me that there is a benefit to having a battery bank that acts as buffer so that you don't need the close matching of genset output and drive load. It also seems to me that on most boats a disproportionate amount of engine run time is being used to charge the battery bank. A genset should do the charging faster and thus run much less. Since I am also a cat sailor and don't wish to have 3 engines on board I still like the diesel electric approach although fuel savings are not expected or required.

[jzk]

Originally Posted by sandy daugherty

We all would benefit from studying Nigel Calder's articles in Professional Boat Builder.

Yeah, in that boat of the future article, he states "Diesel-electric engines can be located anywhere aboard and are more efficient."

What kind of nonsense is that? How are they more efficient? Even the Lagoon 420 owner states that simple motoring is less efficient.

If a diesel vessel motors for 24 hours next to the same vessel with Diesel electric engines, which will use more fuel? I think we all know the answer. At the boat shows, I asked the yachtbroker on every single hybrid whether their vessel was more or less efficient at pure motoring than its diesel counterpart. Every single one of them said the hybrid is more efficient, yet not one could provide any data to support their premise. Not one.

Is there any data out there? I suspect the lack of data also answers the question. It would be easy for these manufacturers to publish comparisons but I wonder why they don't.

[Alan Wheeler]

Yeah, in that boat of the future article, he states "Diesel-electric engines can be located anywhere aboard and are more efficient."

Absolute complete pure fantasiful rubbish. Every time you convert energy, whether it be electric, hydraulic or even simple gears, energy is lost.

[Joli]

Nigel also fitted a standard diesel/tranny propulsion system in the boat. Not sure if he is sold either.

[henryv]

Originally Posted by Alan Wheeler

Absolute complete pure fantasiful rubbish. Every time you convert energy, whether it be electric, hydraulic or even simple gears, energy is lost.

True however if you consider that the generator and motor are replacing the gearbox admittedly with greater efficiency loss but then factor in the consideration that you can keep the generator at it peak efficiency range you probably get at least a wash. If you then consider less engine run time for charging batteries since that is what the generator does best you should have fewer engine hours and save a little. Add in supplementary power sources such a solar ( hopefully soon at higher efficiencies) then you should come out ahead.

Clearly the hybrid approach is still tough to justify on a pure economic basis but for sail boats it should not be long before the technologies improve to the point where it will be viable.

[jzk]

Originally Posted by henryv

...you probably get at least a wash.

There is no "probably" about it. It either is or it isn't, and based on the lack of reporting data, I suspect it isn't.

[sandy daugherty]

Fantasible rubbish.. Is that Southern Hemisphere English?
Read the Articles! Inefficiencies pile up in the best of homes: A propeller is most efficient at a single rpm, an engine at another, and there are real losses in a transmission. The best we can hope to achieve in a conventional installation is to minimize the inefficiencies at a setting we are most likely to use for the longest time. See all the gaps now? In a hybrid system, the engine runs ONLY at its most efficient range, and shuts off otherwise. The batteries also have their own happy places, and that can be managed by controllers that cost nothing more than "a few disgruntled electrons." And electric motors can be built to match prop optimums instead of vice versa. Its always shades of gray [grey] but there's always a brighter side. I read an article some time back about a new container ship powerplant that turned 16 rpm, optimum for a 20' propeller to push the vessel at the perfect speed for the bulb bow. It saved a penny or two every time the prop went around.

Why do I suspect someone will correct my numbers?

Originally Posted by sandy daugherty

Why do I suspect someone will correct my numbers?

There will be no correction of your number because you presented no NUMBERS. You presented a story. I disagree with the conclusion, but don't know where you went off the rails.

Most sailboats don't use enough fuel to make the dollar and energy cost of manufacturing a D/E system worth it.

Those sailboat that DO use a lot of fuel, tend to use their engines for long periods of time at cruising speed, exactly the optimum efficiency point for a conventional setup.

If you actaully have numbers to back up your argument, let's see them.

[sandy daugherty]

What ever you do, don't read the articles in question, they include NUMBERS!

But you are referring to my last two sentances, which are only a dim recollection of something I read or saw on "The Science Channel" about a very big ship. I don't have to remember numbers, I'm old! Besides, I don't argue anymore; Im retired, and the checks just keep rolling in whatever I say!

I'm developing a theory about how well people read these strings compared to the sun's position relative to the local yardarm in their time zone.

[Joli]

Like most things in life...................

time will tell.

Originally Posted by Joli

Like most things in life...................

time will tell.

Joli,

You are so right!

I hear a lot of people arguing that these d/e power plants are just the cat's meow, but I don't see a lot of people lining up to buy them. I looked at them very carefully when I was considering repowering, and the numbers just didn't add up.

Sandy, and others, keep missing my point. You certainly CAN imagine an operating scenario where a D/E system is more efficient, and the articles he refers to that suggest D/E is the way to go make exactly those cases. If I was a commercial fisherman operating a trolling boat a D/E system would be very strong contender for an optimum power plant. Spending long periods of time at low throttle settings, at very low efficiencies and then needing a high speed to get home. Exactly the boat operating scenario where a hybrid power plant would shine. The generator running at peak efficiency just often enough to top up the batteries, and then at full blast to power the boat home. But (there is always a but...) you can get much of the advantage with a conventional drive and a variable pitch prop. Which is better? I don't know. I haven't run those numbers.

Cruising sailboats just don't run their engines that way. I don't know anybody who operates a sailboat engine for hours at 1/4 throttle, a very inefficient place to be running. If the engine and prop are well matched to the hull, you should be operating at your normal cruising speed very close to the optimum point for both.

If I take a standard sailboat design and tweak it to optimize it for a D/E plant, I would put on a much larger diameter propeller that turns much slower. This would require significant rework of the hull of most boats, and for a sailboat a folding or feathering design would be required. I would assure you MUCH better efficiencies under power. Almost every sailboat on the water has a prop that is too small in diameter, and consequently must turn too fast for optimum efficiency. The reason for this is NOT the power plants available, the reason props are so small is that they fit and minimize drag.

If I made the same modification to the conventional boat with a transmission to match the new, lower shaft speed, I would see a similar increase in efficiency. That's the other fault in most of these arguments. The changes they make to the boat improve it's efficiency under ALL forms of power, but they they claim the improvement is unique to the DE system.

[Alan Wheeler]

Hi Sandy. We have discussed this subject in huge depths on the forum. It would be well worth you also taking some time to read what info is here. Just because it is Nigel Calder, so what? We have some of the best in the industry here as members.
Now part of the issue is the apples and oranges thing. There is no equally measured comparison of apples. Lets take the word "transmission" for instance. Yes there are losses. But how do you quantify the loss. Each make and model has different quantities of loss. There is no fixed number we can quantify. I hope that makes sense. So you can not say a gearbox is less efficinet than an electric drive. Because even the electric drive has not been quantified. We could go from a very simple Diesel/electric combination for instance. As the Diesel engine revs, so does the DC electric motor rev. However, we have the diesel to generator conversion adding loss, then we have cable loss, then we have loss ion the DC motor. Now lets take it a step further. We add in Solid state control. That creates a loss. But we have better torque control of the DC motor. With solid state control, we know have the ability top add in batteries and other charge devices like Solar and wind and even boat speed. But we now have battery banks which create some of the highest losses of energy. As long as we have free Wind and Sun, then that offsets, but the big issue we still have at the moment, is the weight and size of batteries. That will hopefully change in the not to distant future. But cost will still be the major concern of those systems. So you see, it is not quite as easy as saying Electric hybrid is more efficient than Diesel. It really depends on the complexity of the system.
Back to the gearbox thing briefly, A simple single speed box is actually quite efficient. The more gears you have, the more energy is wasted. But if you have a simple installation of say Engine-simple fwd/rev box-coupled directly to shaft, that is still one of the most efficient devices available. However, more complex boxes making direction transitions smooth etc, end up also wasting a lot more energy. So it depends.

[sandy daugherty]

Alan, I'm catching up on the previous posts on the subject, and there are a lot of diverging issues. I am interested in only one thing myself, thats getting or staying out of trouble, without causing a new set of troubles. Nigel Calder is not an ultimate authority on anything I care about, but he is a consistent measuring stick of known size, with the ability to present competent explanations of issues that don't submit to common dimensions. He's a good way to compare apples and oranges. [yes they do go together sometimes.] Think of him as the Consumer's Reports of Boat Tech, something to help you make decisions if you don't already have extensive knowlege of both sidesof the subject.
We are (as in any group of individuals) somewhat Jingoistic about our past choices or decisions. Something makes us defensive about not having the latest, biggest or smallest or bestest of something. Probably because something as personal as a boat is, more than a car, a piece of ourselves. Thats good. Knowing some part of who we are is very much better than wondering.
We are often guilty of "Contempt Prior to investigation." That's forming an opinion of something, like an anchor, before we have a good idea of its advantages and disadvantages. To my knowlege, anchors have never expressed an opinion of me, other than an occasional bite, on the same toe, each time. If you follow my chain of thought, you'll understand that I believe all three of my anchors are still getting to know me, and when they do, they will be a lot more willing to help. And when it comes to chafing gear, Sun Yat Sen urges us to thoroughly know our enemy.

The articles are dense and technical, but they are fair and are written from the perspective of, and for the benefit of a cruiser. In the end, Nigel's conventional conservatism has led him to chose a propulsion system that is not far off the beaten path.

Boring.

I don't praise Ceasar. If he doesn't turn around and love my catamaran, and dies of natural causes, I'll probably RSVP the services. But I do think people should have the tactical advantage of knowing which direction to shoot before pulling their triggers. I mean, what if, God forbid, the man actually said something I agreed with?

[fastcat435]

Having a diesel electric system with or without batteries can be more efficient than having straight diesels, the other advantages are of course also having less noise , smoke, sooth centralize weight and having the poissibility to recharge while sailing.
In the system we have developed and that is being tested as we speak we can regenerate anywhere from 300 watts up to 5000 per hour per motor , in normal use on a long cruise one of the motogens ( a new name ) is needed for anywhere between 1 to 6 hours per day for the total electricity needed in 24 hours and that includes the hot water heater and electric cooking . Yes generating electricity this way always costs speed , in our case depending on the speed between 3 and 7 % of the speed if compared without having the motogen hanging in the water. Therefore the use of this motogen we try to limit to hours with more wind. If in a race the units are not used at all and all energy comes from the wind generator ( Air Breeze Masthead mounted )and the solar panels ( 4 x 205 watt sanyo ) If going thru the Doldrums or a longer period without wind the generator is started up to motor as efficient as possible.
All the above is done with 2 x 10 Kw retractable motor/generators on the FastCat 455.
In case of hard winds we lower both units to regenerate and slow the boat down at the same time.
It is not just a matter of using fossil fuel or not, the challenge to sail as clean as possible is also an issue. Cost of fuel is another.
A next step with electric drive systems may very well be hydrogen and all electric boats are alread prepared for this type of propulsion, just ad a hydrogen generator and a watermaker could be the ultimate answer.
Greetings
Gideon