Electric Main Drive(s)

[dana-tenacity]

You got me curious, so I found some old log books and came up with minimum estimate 2.5%, maximum estimate 5%. Admittedly there were places where it was higher ( and places lower obviously ), Sea of Cortez comes to mind, probably up around 40% there.Offset against long passages where IO would never motor other than an hour every 4th day for battery charging.

[planetoftheapes]

That's excellent! You are a superior sailor. I motored or motor-sailed everyday coming up from Cabo. I motor everytime I enter a strange anchorage. I motor often to prevent entering a new ahchorage at night. This convinced me of the importance of having the capability to motor for extended periods. It would be hard to convince otherwise. Why else would we spend so much time talking about this stuff?
You have far more experience than I.
Is you thinking we should be able to make do with a 25 mile battery only range then recharge while sailing? No diesel required?
Have you sailed the Mediterranean? What were you sailing?
I look at my boat as a way to expolre by sea with my family. She is a vehicle and home. I am not so much a purest. I want comfort, joy and safety.

[dana-tenacity]

I wouldn't presume to tell anyone else how to go cruising. If it works for you and yours that's great.
I think that in the dim dark past if you went cruising there was no option but to quit your job, leave and never come back, at which point another day or night at sea is no big deal. Nowadays there are lots of part time cruisers, who only go for short periods, either to return or leave the boat and come back next year. This alters one's perception and drifting around for a day or two isn't as appealing. I used to consider a calm an excellent opportunity to clean up, cook some better food, do maintenance, or sit and watch the bubbles.
I'm just an interested observer in the electric power thing. I'd love to be disconnected permanently (possible) but if asked I'd say a range of 300- 500 miles under power would be adequate for a long term cruiser.
My other stipulation would be that I'd want the option of lifting the drive out of the water, they all seem to need big props, so once the batteries were fully charged I'd want them out.
While a multihull convert I still can't find a solution to self steering I'm comfortable with.

[planetoftheapes]

ID,

Have you given any thought to simply adding a second smaller generator? Maybe a lighter DC generator/battery charger instead of going to 21.5 KW? I realize this defeats some of the advantage of the electric motor system but it would also provide a back-up generator, better efficiency motoing at low speed and prevent running an enormous generator to power AC at anchor.
I know - two diesels to maintain, maybe heavier than a single large generator, difficult the find a space...
but still many advantages...

[planetoftheapes]

Can someone please explain why the 420 is using an AC generator to run DC motors? I just don’t get it? A lombardini 13.7 KW 12 to 120 Vdc generator weighs 260 lbs and you can buy it with mechanical air conditioning and refrigeration. This is half the weight of the small Lagoon Onan generator. There would be no need for a high power inverter to run the engines and charge the propulsion bank plus they increase fuel efficieny. If weight is such a big issue on a cat what’s the point?
I thought maybe they wanted the big AC gen to run the a-conditioning, but why not just run it off the diesel mechanically? The fridges are 12 volt and could easily be run off inverter, or made mechanical. I already posted the 72 volt to 12 volt converter so that big 12volt inverter loads could be run off the propulsion bank. If you anticipate decreased fuel consumption, eliminate the extra fuel tank and weight of fuel and eliminate 700 lb of (21.5Kw) generator by replacing it with DC you open the possibility substantially increasing the battery bank size. This would create some serious energy independence by sail charging the banks and still motor full speed for a few hours.
With a partial lithium bank things get even better (I know careful mixing battery types). I will post calculations when Valence gets back with my quote.

Please what am I missing?
Also, the system at 72 volts makes life difficult all around. This is an oddball component voltage. I know why they say they did it, but then why were they installing 144 volt Solomon systems? Why not just stick to a standard 48, 96 or 120 volts?

[RandyAbernethy]

Perhaps a reason for the AC genset is that most marine gensets are AC. There are solutions galore for AC gensets powering everything on a boat. I have a dive compressor that would be a pain to power with a DC genset. It could be done easily, but it isn’t done, so it’s hard (read: “time consuming, voids warrantee and you’d be the only support for it). Problems include AirCon, many water makers, anything built for shore only use, etceteras.

I originally had thought the 420 had a DC genset and so started investigating how I could set things up to operate entirely DC and it was not so simple. Fundamentally it should be easier but changes like this happen in steps and an all DC boat is a big step. I’m willing to let Nigel Calder figure DC out (which he seems to be doing) and then serve up a debugged solution with ready made parts from brand name manufacturers for the rest of us. Mr. Calder is also working on electrical distribution systems that will greatly reduce weight and simplify circuits within boats.

Were I to purchase a 420 I think I would choose the smaller genset. Principally because power consumption is nonlinear as speed increases. I’d be happy to trade a knot under power for ½ the genset size and 30% better fuel efficiency. The 420 should lose no more than a knot of speed when the 13.5 genset is set to house/drive with 60% of the power going to the house (perhaps taking you from 7 knots down to 6 knots). I base this on the results of the L440 test mules running the 420 propulsion system. Where I grew up we were taught that all sailboats go 5 knots as a crutch for guesstimating time/distance etceteras. I suppose if your expectations are 8 knots under power the 13.5 genset doesn’t fly, but that is not a universal expectation. The amount of additional fuel and weight you have to throw at the problem to go 8 instead of 7 (or 6 for that matter) doesn’t add up to me. I always marveled at boats with gensets bigger than 6KVA, and for house use when not motoring 21.5 is a bit much.

Noise is mentioned above. I would expect any diesel electric system to be much quieter than a traditional diesel setup. Gensets are just quieter. They are better insulated sonically (so you get double insulation with the engine room) they run at a constant speed and can be turned to minimize vibration better and these days they are humming along at 1,500 or 1,800 rpm. You could get folding props with lock outs for the 420 as well. In folding mode you gain boat speed, when locked you can regen.

We have a long way to go in this arena and I imagine there will be growing pains. As long as you take the right approach I think that you can operate in a more green fashion with the boats coming out now. If you want 8 knots and AirCon you may need to wait a year or five before the "green" power necessary is available.

[planetoftheapes]

Thank you for your informative reply. Can you tell me where the DC systems are so difficult to design? I assume Lagoon is using AC gen because that is what the Solomon system design they "borrowed" does? This is bothering me. I just want to know for my own edification. If I am going to take the 420 to far away places I need to understand the system.

It seems if anything, the AC gen induces an extra level of complexity and DANGER. I have found DC genset battery chargers online. As far as I know almost all sailboat currently have DC systems with engine driven alternators and inverters for house AC. Many have AC gensets also of course.

There is nothing I can come up with for this even being an issue. Utimately isn't the L420 electric engine system already DC. You just powered/charged by AC to DC conversion.
Air cond, watermakers, refridgerators and compressors can be directly connected to the genset or a large inverter(s) can be used to run just about everything off the battery bank. This system could have been so much more non-electrical. A good thing in a salt environment.

I am sure there are additional inefficiencies involved in converting AC to DC. We are adding hundreds of pounds, increasing noise, decreasing efficiency and increasing complexity for no benefit I can discern.
I only vaguely remember my electrical engineering courses, but it seems you could sit down a design a simple effective DC system based on the battery bank.

As far as genset size, I think you have changed my mind. I was going to order the large genset. I did not fully consider the non-linear power/speed curve. It probably requires twice the energy to go form 5 to 8 knots. Great! I calculate about 2.5 hours of motoring time at 10 Kw starting with a fully charged battery bank in all power to engine mode. This is probably sufficient in case of emergency. Yes, I agree the trade-off, 5 knots to be able the run air cond and save the weight, is reasonable. Thanks. I can always add an additional small DC generator/charger if I turns out I need more capacity.

If you have experience with the L440 electric can you tell me if you can motor into a chop/wind at 5 knots and run the air conditioning?

[planetoftheapes]

Just a bit more food for thought. http://www.amemco.com/ has a 6 kw electric outboard motor. This is for me! Use 2 or 3 of them. You can lift them out of the water. Get rid of prop drag, shafts, stuffing boxes, expensive, vulnerable motor controllers... Dump the complex electrical system of the 420. I wanted an electric cruiser not the space shuttle.

For regeneration buy a water generator specifically designed for the task and manage it yourself.

Water generator, solar, wind ------
DC generator/battery charger/air/-- batteries -- motors
-- inverter -- houseAC
-- 48 to 12 volt converter -- house 12 volt.

It would be such a simple, redundant, light weight, easy to maintain system. The outboards are submersible, light weight and so unobtrusive they could be mounted right on the end of the transoms.

[GordMay]

In general, AC Alternators, motors and other electrical equipment are simpler, cheaper and more reliable than their DC counterparts. AC electricity can be easily transformed into higher or lower voltages making it more versatile than DC electricity.

Essentially, a DC Generator* is an AC Alternator* with the addition of a split-ring commutator.

In an AC Alternator, the brushes run on slip rings which maintain a constant connection between the rotating coil and the external circuit. This means that as the induced emf changes polarity with every half-turn of the coil, the voltage in the external circuit varies like a sine wave and the current alternates direction.

In a DC Generator, the brushes run on a split-ring commutator which reverses the connection between the coil and the external circuit for every half-turn of the coil. This means that as the induced emf changes polarity with every half-turn of the coil, the voltage in the external circuit fluctuates between zero and a maximum while the current flows in one constant direction.

On a generator windings of wire (the armature) spin inside a fixed magnetic field. On an alternator, a magnetic field is spun inside of windings of wire called a stator to generate the electricity. This allows the wires to be directly and easily connected to their outputs without the need for sliding contacts to carry the relatively high output current.

* Technically-speaking, a generator produces DC and an alternator produces AC, but the term "generator" seems to be used as a general term for both.

[Intentional Drifter]

FYI, the Solomon system uses a specially built 144volt, DC genset, not AC, built by a Fischer Panda subsidiary. The genset system has been a problem for a couple of the first generation Lagoon boats. Several models of F-P gensets have been noted to have had serious design problems (as described at: http://www.sailemerald.com/16236.html ), although F-P should definitely be credited for working with owners and making good on them.

The other issue with the genset choice for the Solomon system is that it is not a standard model, but rather custom for Solomon. I imagine parts and servicing concerns also played a role in Lagoon's decision to go to a standard genset.

There are a number of sometimes conflicting desires and values that a boat's designers must balance. They are surely going to make decisions that would not be what someone else would do. That's why there is room for custom builders. At least some of them seem to do pretty well and have a good business going.

ID

[planetoftheapes]

Yes, Richard I stand corrected. The Solomon system does use a 144 volt DC generator. I just made an assumption...

I ordered the 420 without doing my due diligence and have been trying to get up to speed for the last few weeks - a bit manically I might add. It's been alot of fun. I've got a good handle on this now.

The complexity of this system concerns me and as does the huge weight issue. There are many high-powered, expensive components to fail on this boat.

The Fast Cat 435, although not aesthetically pleasing to me, is really my cup of tea philosophically - a similar philosophy to Gunboat and Farrier. That is how my custom catamaran would be built. I did and still am considering these ships. If it was just me, it would be all about speed. The interior volume, especiall in the hulls is sub-optimal for us.

I will be cruising with my wife and 3 children and the vastly superior accommodations in the 420, with a $370K price well equiped and to me rugged, functional beauty was an easy choice. The Fast Cat will run $550K-$600K out the door. I trust Lagoon will not drop the ball on this.

I have to say, if the sea trials are not encourging, I may bite the bullet, lose my deposit, and switch to Fast Cat 435/500, Sunreef 60/62, Gunboat 48, although don't want to work the extra time to pay for them.

Thanks guys- I stiil think a retractable, submersible electric motor could be the best of all worlds, and Solomon should have designed a 120 volt system then they could have used an off the shelf generators and other electrical components. It is similar to Lagoon using 72 volts. What the heck? The first law of engineering is to design systems using components that are already commercially available-don't try to reinvent the wheel. Starting from scratch costly and time consuming and often unreliable.

[RandyAbernethy]

Solomon seems to be a really innovative business and I love their push to build green technologies. I’m sure that Lagoon learned many valuable lessons interacting with Solomon. That said, Solomon is a bulletin board stock.

The Lagoon 420 is a big push into a new arena by perhaps the largest firm in the catamaran business. They are taking a huge risk on the Diesel/Electric configuration. To make it work they need volume suppliers with highly reliable and proven solutions in the component areas. Thus Lagoon has selected experienced, quality component venders with substantial resources in each of the major systems areas.

For example, Leroy-Somer is an ISO 9001 firm who has been building CE marked marine electric systems for 10s of years. The firm is owned by Emerson (market cap of $34 billion) and employs over 8,000 people. Onan is one of the best names in the marine generator business, also with substantial resources for manufacturing and support.

The absence of a DC genset has nothing to do with lack of feasibility. AC to DC power conversion and DC to AC power conversion both exist, are well understood and operate at about 90% efficiency. It’s more like, “how much of the apple do you want to eat in one bite?”

Most of the cool technology cruisers enjoy wasn’t made for them. Adapted, repackaged and remarketed, perhaps, but not made for (obviously there are exceptions). Largely things come to us from upstream. The world uses AC gensets by and large right now, so if you want a high production, reliable, easy to service in every corner of the world genset, I think an AC Onan is a good selection.

[planetoftheapes]

I found these post from Solomon. Clears things up for me.

Gentlemen....Solomon Technologies 120/144 questions....our motors are voltage dependent(the higher the voltage the more RPM's it is capable of) and when we do a diesel electric hybrid where the generator keeps that voltage above 120 then we can go with only 10 batteries. When we sell a system that is using only batteries we go to 144 so that there is a larger spread in voltage (full charge 162vdc to 80% discharge at 120vdc). We are presently thinking about sticking to 144vdc for all boats. Now, having said this....DO NOT GET HUNG UP ON the Batteries and weight...if you have 10 group 31's ...it weighs that same as 12 group 27's...it is entirely adjustable to mission profile. And as a diesel electric hybrid (see Ted Turners 40ft Condor Trimaran) the batteries can be adjusted to only last 20min.(UU1 Deep Cycle Wheel Chair batteries) becuse when the generator comes on it will motor you as long as the fuel lasts like any other boat. He has just enough batteries to take care of his "normal mission profile and cycle of use". He TYPICALLY only needs the motor for 5 to 10 minutes to get out of the slip and 5 to 10 minutes to get it back.....under normal conditions he has all the power he needs with 10 20LB batteries....when every thing goes wrong he turns generator on and uses fossil fuel.
Dave Tether
Gentlemen...First...our motors are designed to be capable of 4KW (6HP) at 120VDC....that means you can actually get more power out of them at 144VDC (but we limit the control so you can't...sorry!...they last longer). Depth of discharge is really independent of voltage...but for one principle...in watts ...voltage and current are inversly proportional...and...the true measure of how much depth of discharge you can get on a battery without doing damage to it is current....lower current and you can discharge them lower. To blanket applications with generalized statements doesn't work with lead acid accept when you talk current. Batteries do not like high current draws....that's why we went to a higher voltage. 4KW...at 24VDC=166amps(bad do not discharge more that 40-50%).....at 120vdc=33amps(much better and you can take them down to 60%)....at 144vdc=27amps (even better still and we have taken them to 80% without any damage). It' all in the current...actually we recomend to our users that they only do this in emergency and when they do reduce the throtle control to 2KW(or about 13.5 amps) so damage is prevented. More volts actually yields larger depth of dischare because of reduced amperage to produce the same power.
Also....we are not trying to send every one out there with just batteries! 3/4 of the boats we have done todate are diesel electric hybrids...think about this.....a 4KW diesel generator weighs in at about 200 lbs. with fuel (or 3 group 31 batteries). This means you could go with less amp hours for normal operation but still have the ability to have unlimited motoring if necessary. The key is NORMAL, or cycle of use, or mission profile, or standard operational scinario. The size of the generator(or shore charging capability) and batteries are both on a sliding scale. You must first figure out what your cycle of use is. Also, there is no where in anything I have read or experienced that indicates if you use 30% of the batteries power that it comprises a whole cycle. We have AGM that have been routinely charge and discharged to 40% hundreds of times with no degradation in performance at all.
This is not how FF motors work and there is more to think about.....BUT....you can taylor a diesel electric hybrid/electric system to your specific needs and minimize energy usage or increase energy usage with more power and ammenities. I personally chose more power....Yes I have a 28 ft. sailboat with TV/VCR, Microwave, electric stove, refrigerator, stereo and electric back masager......for me more power.

Again this is a cut and paste. Not POA

[Intentional Drifter]

I hear you -- if only my priorities were being considered, then I'd probably go with a Farrier F-41 or Fusion 40, perhaps with the Solomon system, maybe with the Ossa. But, there are other desires in the equation, too. When my wife and I went seriously boat shopping at the Miami show, we arrived with 14 "possibles". The goal was to get the list down to 3 or 4 and go from there. The Lagoon was not even in the 14. So, we go through the list (which included several used boats of interest that weren't in the show) and get it down to six. We go back to the show, and then really just so we could say we gave them a chance, we went to see the Lagoons.

Well, wouldn't you know it -- the Lagoons ended up having, for us, the best combination of compromises with the greatest number of "really gotta haves" (like wide flat side decks, 4-corners visibility from the helm, forward facing nav station, decent galley storage, anchor forward instead of off the bridgedeck, etc.).

So, we went into this actually with a bias against the Lagoons. But that's what we ended up buying.

In terms of the technology, yeah, we're taking somewhat of a chance. But, I agree with Randy. Lagoon has picked good, solid partners that are also financially stable. (Solomon looks on the knife's edge of survivability. Never a good sign when they look to be pinning the future balance sheet on winning a lawsuit. Even less hopeful when it is against Toyota.) Lagoon is taking a far bigger chance on this than we are. If the whole concept goes down the toilet, even if we already have our boats, we can always spend the money and retrofit to conventional systems. Lagoon can never get back lost sales and revenue.

ID

[RandyAbernethy]

ID,

I had the same worst case scenario thought. $550K for a totally loaded 420. If all goes bad add another $100K (parts, time, trouble, rewiring, etc.) and you have a twin Yanmar 420 with a serious genset. $650K is high but still inline with a well equipped used 470 (and the 420 has about the same interior volume).