Electric Main Drive(s)

[Intentional Drifter]

I took the fuel consumption data for the two Onan gensets, from the Onan website and charted them out for comparison purposes. The chart illustrates expected fuel use (at 60 Hz, since that is what the 420 uses for motor bank charging) for both the standard and optional gensets. You will see that the standard (13.5) is more efficient up to the point of its maximum power output. Of course, the advantage of the 21.5 is that you will have power to spare for full motor output, as well as some overhead for other uses. That comes at the cost of increased fuel use and weight.

ID

[TonyWest]

Hi, Guys, my name is Tony West. I'm new to Cruisers Forum, but immediately noticed how much interest there is on the Electric Drives and Lagoon 420 forums.

Thought you might be interested to read about my boat, the first Electric Leopard made by Robertson & Caine, so I set up a R&C Electric Leopards discussion, which you'll find under Multihull Sailboats.

I'll post more next week,

Tony West

[northerncat]

yes i have read about the leopard electric boats, i think that their solution is a lot more elegant than the lagoons
sean

[planetoftheapes]

I am unclear how having no battery storage would be considered “more elegant.” With the Mooring’s system you lose the ability to store wind energy, you lose the huge at anchor battery power, you lose the couple of hours of motoring if the generator fails, you lose always available instant motor power, you lose all generator independence. There are major advantages to having a battery bank.

Without batteries you save in the weight department but at a huge cost. Granted, the Lagoon system is rather complex but by report they have tested this system for many years.

Without the battery bank much of the hybrid concept is lost.

The Mooring’s system simply replaces three diesels with a large DC generator. While this is likely to be a considerable advantage, in many ways it might be considered less elegant in the context of a “green” system.

[Quiet Riot 420]

POTA

Well said, I could not agree more (the 4300's genset will be running almost all the time, whether motoring or at anchor), but I can see where Tony got his bad impression of batteries, "Waypoint". According to different posts by LtBrett, who has captained "Waypoint" several times, the regeneration capabilities of that Solomon powered boat was only about 10 to 1, as in 10 hours of sailing to get 1 hour of battery motoring, not all that good. Lagoon is claiming to have improved the 420 design so that you get about 1 hour of motoring for every 5-6 of sailing. Of course,the faster you sail the faster the regen. We shall see, as I am due to go out on 420 sea trials the day after the Miami boat show.

Fair Sailing _(\_
Quiet Riot 420

[GordMay]

Technically & scientifically, “Elegant” could be paraphrased as “simple”, or stripped to it’s essence.

[northerncat]

but surely your house bank would benefit and pretty much use most of the available solar and wind that could be installed without having an ugky boat,
how much anchor power do you need? surely you only expect to use the anchor winch for five or so minutes a day not hours and hours

i would agree with the battery comment on a nice heavy mono but on a cat it just seems wrong
sean

[ess105]

PotA was referring to "at anchor" power, not anchor power. One of the appeals of the hybrid concept is that you can sit at anchor for many days without having to be miserly with consumption and/or run genset for an hour or two per day. On the Leopard you could get that by adding lots more house batteries but then the question would be - why can't I use all these batteries to drive these motors and get me out of this anchorage to the where the wind is and where I can get more juice.

[planetoftheapes]

"Technically & scientifically, “Elegant” could be paraphrased as “simple”, or stripped to it’s essence."

Yes Gord you are correct, but in this sense the elegance is in the context of a solution to a specified goal.

If the goal is to replace multiple diesel motors with a high efficiency generator then the 4300’s system is hands down more elegant.

If the goal is a catamaran that can store “free” energy and have the potential to operate completely free of fossil fuel then there is no comparison between these two systems.

The Lagoon and Mooring’s system are not different solutions achieve to same goal, they are different systems that achieve different goals.

If you accept the goals achieved by the two designs are different then it is incorrect to call one system more elegant than the other.

This is no small point because a major reason people are drawn to the L420 is the ability to operate totally green. This is not an option in the 4300.

[Lodesman]

I thought about the downsides of the Leopard system too, but house supply would be no different than any other non-hybrid boat; you could use solar or wind at anchor. There really is no reason why the electric motors could not be used as generators under sail. Not having instantly available (and quiet) propulsion is the biggest drawback, but not any different than non-electric boats. I think this system is worth serious consideration - as all things boaty, there are compromises.

[Intentional Drifter]

Looking at it from an evolution of design point of view, I would place the Leopard/Ossa system as in between a conventional boat and the 420. Certainly an improvement that has advantages in the reduction of fossil fueled propulsion and reduced maintenance of the dirty bits. The 420 is a bit further step toward a green boat that does not rely upon fossil fuels at all, but it is not there, yet.

While it may be possible for the 420 to take on a daysail or a passage without resorting to fossil fuel, I frankly doubt that will happen very often without the most favorable of conditions. Lagoon's response to the problem brings on problems of its own in the form of electrical complexity and the weight of all of those batteries. (Yes, Dave, I do see those as a downside and my preference would be to see them either gone or greatly reduced in weight.)

Now, maybe, Lagoon's response also has another advantage: if better, lighter batteries can actually be used (and affordable), then the Lagoon has the potential to incorporate them -- probably with relatively minimal retrofitting of a few components and firmware. So, it might get better over time. The Leopard/Ossa solution seems to be stuck where it is. While the components may become more efficient, more reliable and/or lighter, the basic conceptual design is a final response to the problem posed.

Still, the Leopard is a positive response and I am glad to see it. All of these developments help to create a market for green(er) boats and that provokes designers and manufacturers to provide them. I expect that in 5 years, 45% of new designs will have some form of green(er) systems. In 10 years, I expect that to be 95%.

ID

[Quiet Riot 420]

The reason the 4300 doesn't have motor battery banks, is the fact that your would need 20 batteries per bank to achieve the running voltage of 240 Volts
(20 batts X 12V = 240 Volts wired in series). This would mean that in order to have 2 motor battery banks, like the 420, you would need 40 - 12 V batteries, and wieght would indeed be a problem. Further, with the 2 engines drawing 50,000 watts total power, you would need very large deep cycle batteries like the ones on the 420, but 3 1/2 times more batteries.

Fair Sailing _(\_
Quiet Riot 420

[LtBrett]

I admit, I'm scratching my head a little at the Leopard design. I figured electric boats should have either just enough battery power to get them out and back in, or should have a Lagoon-like regenerative hi-capacity system. The Leopard system is not likely to be more efficient than conventional diesel, unless Tony likes to run the air conditioning all the time. It makes a lot of sense if he was already planning to run a genny while underway. Still, those DC genny's can't be cheap to buy or easy to service. Nobody at CatCo would touch Waypoint's high voltage DC bus.

ID: I suspect daysailing a docked 420 will usually be done on electric propulsion only, unless the genny is needed for something else, like air conditioning. There is plenty of capacity for the average unplug-motor-sail-motor-plug in to dock cycle. A moored 420 will probably be run on the genny more often than not to top off the batteries while underway.

QR: 10 batteries bridged between 2 banks or a simple DCC transformer should cure any voltage issues, vs adding a couple tons of batteries. But its good to see the question of the ideal voltage for an electric motor is very much under investigation: 72 vs 144 vs 240 vs ??

Brett

[BambooSailor]

Originally Posted by LtBrett

QR: 10 batteries bridged between 2 banks or a simple DCC transformer should cure any voltage issues, vs adding a couple tons of batteries.
Brett

Unfortunately, you cannot transform DC (that's why Tesla won the battle over his boss Edisson, remember? ), you need an inverter. I personally prefer lower voltage (e.g. 72V) for exactly the reasons mentioned previously in this thread: you need fewer batteries and you can even recharge them using solar panels (3x24V - I am not sure whether that is an option on Lagoon 420 though). Now that's green. Leopard's OSSA Powerlite system does not consider using batteries, therefore higher voltage makes much more sense.

[ess105]

Given that I'm expecting to perform maintenance myself, I am far (understatement) happier working with 72V DC than 240V DC. To go near 240V DC I'd want to wear my 7mm wetsuit, boots, gloves and all.