Thoughts on a viable and MARKETABLE Electric Drive Train

[valhalla360]

Originally Posted by Yihang

For marine the main barrier for charter market is probably cost right now? Once battery cost halves again we might start to see something like the lagoon 420 electric again.

Charter market is probably OK for range (at least many bases don't have long distance destinations for a typical week cruise) but charter boats need to be bullet proof and more importantly idiot proof. I wouldn't trust charters not to kill the battery bank in a short period by taking it to 0% charge...and then there would be the complaints after they do so, even though they were warned.

The other problem is does the base have lots of marinas, so you can plug into shore power every couple days? You still need to generate the power somewhere and if you are just installing a big diesel tank and generator as the primary source, it makes far less sense.

[carstendenmark]

Hey OP, about the safety of electric sailing, there's some more on the recent thread Electric propulsion - stops or stalls - any experience ?

Electric sailing - we are still pioneers, and let it be that way.
But definitely not the first : https://en.wikipedia.org/wiki/Electric_boat

Sorry to tell you valhalla360, but yet there is NO market for new yachts like this.
Buyers of NEW yachts wants something approved, safe, reliable, easily serviced by any marina service, with easily available parts, and without any hassles.

If someone want all the amazing benefits of sailing an electric boat (hybrid or full electric), they'll have to consider their needs, general use, and common sailing patterns, and later it may be difficult to sell it to someone, who do not want to follow the limitations of an electric boat.

I am going to convert my 1976 Maxi 87 into a tech yacht (like Sailing Uma on Youtube), step by step, but do not expect someone to buy it (easily), if I ever need to sell it (when I'm 6 feet under ;-).
So, I'm aware of the risk of my project, and my investment.
As an inboard diesel driven yacht, it is now easy to sell.
As an electric converted yacht, it may not be that easy...

That's why older yachts still are the only subjects for conversions, as the depreciation value is non-existing.

But those buyers who can value and appreciate the benefits, will surely have a great time, buying an electric boat !


Another issue is that battery prices WILL drop, for sure.
And that battery tech will improve much.

That means, that if you have a full electric powered yacht today, you can easily upgrade your battery bank to extend your range, house bank, etc.

No ICE engine can do that !

[valhalla360]

Originally Posted by carstendenmark

Hey OP, about the safety of electric sailing, there's some more on the recent thread Electric propulsion - stops or stalls - any experience ?

.....

Sorry to tell you valhalla360, but yet there is NO market for new yachts like this.
Buyers of NEW yachts wants something approved, safe, reliable, easily serviced by any marina service, with easily available parts, and without any hassles.

If someone want all the amazing benefits of sailing an electric boat (hybrid or full electric), they'll have to consider their needs, general use, and common sailing patterns, and later it may be difficult to sell it to someone, who do not want to follow the limitations of an electric boat.

....

Another issue is that battery prices WILL drop, for sure.
And that battery tech will improve much.

That means, that if you have a full electric powered yacht today, you can easily upgrade your battery bank to extend your range, house bank, etc.

No ICE engine can do that !

ICE engines have failures also. At worst, it's teething pains. Everything suggested is standard mass produced products and of course, it put together in an unprofessional manner, it won't work well.

As far as resale...that fits in perfectly with my point. This is a common usage pattern so finding someone who would like the option is very likely because it's a viable propulsion system.

As far as you final point, it's pretty easy to add tankage on a diesel boat to get additional range. On our Gemini, we would typically carry 4 - 5gal jugs which increased range by about 1/3 but really that's a red herring issue. No one buys a new boat with the intent to repower it in a few years and really it wouldn't needed anyway as the proposed design would allow for normal usage.

[Andreas W]

Have a look at www.oceanvolt.com

[denverd0n]

Originally Posted by Yihang

Within 5 years Electric Cars are going to have the same range as most ICE cars AND be cheaper.

You know, that's exactly the same thing some people were saying about... oh... six years ago, or so.


Don't hold your breath.

[valhalla360]

Originally Posted by Andreas W

Have a look at www.oceanvolt.com

In principal, it should be a good alternative to a saildrive but...

Just makes me a little nervous with some of their endeavors. Reading their website, they seem to be big proponents of magic electric HP and the Cornel boat failure doesn't leave the warm and fuzzies.

[Ken Fry]

I built a plug-in hybrid minicar a while ago, and it was a fun project (predating the Chevy Volt). It was a series hybrid, with control of engine starting left up to the discretion of the driver. Even in that little car, control was easy to manage -- but one could imagine a time when I would forget to start the engine and pull out into traffic only to find the the battery is dead. (But that can happen to any electric car -- or ICE powered car, for that matter.) Had I forgotten to start the engine, it would have been a minor inconvenience... but I used to worry about it. (Never happened) In a boat, there is scarcely any inconvenience. No more challenging than when the wind dies when sailing.

But the concepts (parallel/ series/solar/etc) are very very simple, and the parts are all available. Getting it right (for a boat, car, airplane is a matter of deciding what mission the vehicle is to satisfy and design accordingly. (Difficult for an airplane) It happens that those of us who did this stuff with land vehicles came up with the same general outline: about 40 mile electric range satisfies the needs of most users, while minimizing battery cost and weight. This applied to my little car, and applied equally to the Chevy Volt (one of which I now drive daily) and to the Fisker (which was unsuccessful from a marketing and management standpoint.)

With boats, the usage patterns vary more widely and it would be a mistake to think that "most boaters will need to..." Certainly, a boat has to go very very slowly to have an attractive kWh/distance figure, so one cannot plan for anything close to 100 mile range on batteries alone, unless one wants to spend a great deal of money on batteries... or go quite slowly. (There was the boat the did the great loop on solar alone.... not impossible, just not very fast. Although that boat went pretty close to trawler speed)

The boat I am now building (which is a solar-charged electric/sail/sun hybrid) will not have an ICE, because I will not need one, most of the time. (I had originally planned for a 30 hp outboard, for use when I wanted to go fast in this very light catamaran, but my usage plan has changed.) Most of my motoring will be to get out of my creek into bigger water and bigger wind. I might do an occasional slow dinner cruise on a becalmed evening, but I have adequate range for that: at very low speeds electric consumption is also very low.) If I want to go far, I'll sail. If becalmed miles from land, I can motor on solar power alone, fast enough to provide a tiny comforting breeze).

I admit to not having read the original post in detail, but it appears that the OP's idea would work well. It is just a matter of doing the math, and seeing if the weight, cost range, factors all can be worked out. One needs to work with real dyno charts of electric motors, engines, generators, etc. rather than the marketing claims... and it helps to have real towing tests for drag (and therefore power consumption) at various speeds.

A series hybrid can work just fine in a boat, if it fits the mission. However, if the intent is to frequently go further than battery range, then there are fewer losses from going directly into the water from an outboard, rather than from ICE-to-generator-to-battery bank-through-controller-through motor and to the water. (This approach gives you a spare motor, as well.) The losses add up -- although each loss can be quite small alone. (The glaring exception is the ICE in which 30% efficiency is doing well. That and the prop, which is another huge waster.)

On the other hand, if you rarely need to use the ICE, then it is less expensive to simply keep the battery charged via a generator of say 30% higher power than you want to deliver to the water... provided you keep that power delivery modest.

All sorts of possibilities. All the permutaions have been done at one point or another in history.

The difficult part is really knowing the market, if this is to be a commercial venture. It is fairly easy and straightforward to build a one off, because the usage is (hopefully) well known. It's harder to come up with a marketable product without doing plenty of market research. I would have thought that the Chevy Volt would sell better than it has. For me it is the perfect car -- it costs next to nothing to operate, but can easily go long distances when I want. I did not anticipate, back when I was involved in designing and building my car (a prototype) that others would not see things my way. Even the Leaf, a decidedly compromised car that in fact (predictably) left many people stranded, would outsell the Volt. I also would not have thought that the $80,000 - $100,000 Tesla would far outsell either the Leaf or Volt -- but I still have a hard time thinking of $100,000 cars as being mass market. Where I live, there are as many Teslas as there are any other car -- they outnumber Leafs or Volts by 300-400%, I'd guess.

My first electric boat was my old Hobie 33. Never had to plug in (the batteries were solar-charged) and only rarely used the gas engine. A tolling motor would move me out to the race just fine. Quiet, cheap, easy... and the batteries powered all the other electrics on the boat. (not much of that.) Simple parallel hybrid. Worked fine. 25 years ago. Things have only gotten better.

[Ken Fry]

Originally Posted by valhalla360

Reading their website, they seem to be big proponents of magic electric HP

Yes. Irritating... and widespread.

And not only in boating. 6hp shop vacs are common. Almost 4500 watts. And you can plug it into a wall socket rated for 1800 watts. The other 2700 watts comes from the tooth fairy.

Their number is not 100% bogus, however. Pour the coals to an electric motor and it can provide an impressive peak power... until it melts.

[valhalla360]

Originally Posted by Ken Fry

With boats, the usage patterns vary more widely and it would be a mistake to think that "most boaters will need to..." Certainly, a boat has to go very very slowly to have an attractive kWh/distance figure, so one cannot plan for anything close to 100 mile range on batteries alone, unless one wants to spend a great deal of money on batteries... or go quite slowly. (There was the boat the did the great loop on solar alone.... not impossible, just not very fast. Although that boat went pretty close to trawler speed)

Actually, I don't think they vary as much as you would think for a displacement sail boat. Sure there are outliers but very few boats are purchased new for long range ocean crossing cruising.

Talking about displacement sailboats, it would be very rare to motor 100 miles continuously.

For a displacement sailboat 5-6kts is a more typical cruise speed. At 6kts,
- 10hr motor would be 60 n. miles. That would be a long day's motoring for most.
- 100 n. miles would be 17hr straight motoring. Not unheard of but very uncommon.
- Realistically most motoring will likely be under 5hr (30 n. mile range). Now you are down where a moderately sized battery bank could handle typical use.
- This is all before considering the longer the run, the more likely they are to get at least some of those miles under sail.

For rare longer motoring runs, a small backup generator could range extend to get 60 n. miles without a performance drop and if you are willing to cut the speed a little, you could go even further. But as with PIH cars, most miles would still be pure electric.

This is in the range where you could sell it to a new buyer's who want the "eco-street cred" but aren't willing to live with 3kt cruise speeds.

Now if you want to make a trawler, sure you need more range and speed as the expectations are higher. Typical cruise speeds there are in the 7-10kt range and with no sails, even longer runs, you need power.

As far as running the math, that's why I chose a Gemini. We spent a number of years and a lot of miles motoring on the Great Loop. I have a very good idea of the performance and how much power is needed...then I made my assumptions a bit conservative. Example: 10kw is probably a bit high to make 6.5kt but it's horrible marketing to oversell and under perform. As soon as the stories come back that the marketing is BS, future sales get a lot harder. But if you claim 4hr at 6.5kt and people come back reporting 5-6hr is possible, it self markets.

[valhalla360]

Originally Posted by Ken Fry

Yes. Irritating... and widespread.

And not only in boating. 6hp shop vacs are common. Almost 4500 watts. And you can plug it into a wall socket rated for 1800 watts. The other 2700 watts comes from the tooth fairy.

Their number is not 100% bogus, however. Pour the coals to an electric motor and it can provide an impressive peak power... until it melts.

I don't think anyone with even a slight bit of knowledge, thinks and electric motor can't put out lots of power. It's the recommendations to undersize everything based on magic HP equivalency.

I believe they have taken on honest truth and misapplied it either thru lack of understanding or by purposely being misleading.
- With cars, cruising down the highway, you may only need 40-60hp to maintain highway speeds. Look at the old VW Bugs. They started with only 25hp and a top speed of around 60mph...but it took half the day to get up to speed. Even the last models off the production lines were only 60hp. You will be hard pressed to find a modern sub compact car without at least 120hp engine. Of course, they rarely if ever actually generate 120hp. The reason is because ICE generally don't produce max torque at low RPM. An electric motor though can generate max torque from zero RPM. Since HP = torque x RPM, an electric motor of the same max HP rating will generally produce a lot more low end HP. Therefore they can reduce the max HP with an EV but so long as the low end HP is equal or greater, you won't feel a performance loss.
- A slow speed displacement sailboat doesn't have that same issue. Maneuvering, it's rare to use even 20% of max HP (there is theoretically a small advantage of being able to go forward to reverse without pausing but panic moves are rarely a good thing). Acceleration up to 6kts, most people really don't care how long it takes. Also since the prop will slip, the motor will have spun up to it's ideal torque output within 2-3 seconds and any differential torque advantage is largely lost. Once you are up to speed, both motors are putting out plenty of torque & HP, so it doesn't matter which power source you use.

Now if you are talking about a small planing hull, the car example might have a bit of truth. It's not uncommon for a marginally powered boat to struggle to get on plane. If that low end torque can pop it up on plane, once on plane, the power requirement to hold plane is often less (though top end speed will suffer a bit)

PS: a 6hp shopvac is an outright lie.

[Ken Fry]

Originally Posted by valhalla360

Actually, I don't think they vary as much as you would think for a displacement sail boat. Sure there are outliers but very few boats are purchased new for long range ocean crossing cruising.

I agree, in principal, that usage patterns for displacement sailboats vary less than those for the whole boating world. My point was that there is a great deal of statistically viable data regarding car usage, and less of that for the sailing world. I and Chevy and others promoting plug-in hybrids could say 15 years ago, with confidence, that 40 mile range is adequate for more than 90% of commuters. We could also say that there are a great many cars used for commuting -- so when it comes to rounding up money for such a venture, people can see dollar signs.

In the boating world, that is not the case, and even in the displacement boat world, there are huge variations in usage patterns, and great variation in what people imagine they are buying when they buy a sailboat. Thousands of people have bought "blue water" sailboats, but never take them offshore. (Just as millions have bought Jeeps and never take them off road.) Engineering and marketing are much different disciplines.

I think your ideas and presentation are rock solid, from an engineering standpoint. Yes, it will take less than 10kw to go 6.5 knots in a Gemini with a clean hull. The Gemini is a good choice because of available space for solar cells (and it also has the attractive aspect of just having plenty of space for hanging out). They are relatively inexpensive, so the market could be larger than for a larger or snazzier boat. It you go ahead and build it, it will work as you have planned.

Our thoughts regarding this stuff, from an engineering perspective are nearly identical. 60 NM is a very viable range, albeit on the high side for the average coastal cruiser. The boat I'm building now is a narrow 30 foot cat, a solar/electric sailing hybrid. However it is half the weight of a Gemini, and has negligible creature comforts. I'm willing to trade comfort for lower drag, and thus greater range per kWh. I am also OK with 30 NM range, in the interests of less battery cost, and less weight. Many people would not make that trade. However, there are a lot Farrier tris around, indicating that plenty of people are willing to sacrifice creature comforts for speed, responsiveness, thrills, trailerability, etc.

The point being -- I agree with everything you say -- we are very much on the same side. But the boat I'm building is much different than the one you envision. It's not better, and yours would have a broader market, I believe, but they are just different. And that is the nature of the sailing world. Two J24 sailors can get together and argue all day about very slight rigging differences allowed within the very tight rules. There are Snipe sailors who would not dream of sailing a Lightning. Sailors are a fabulously quirky bunch.

So... My caution is that it might not sell as planned. (Or it might sell better than planned.) In either case, solid market planning can help avoid a painful experience. I can think about the advantages of a plug-in hybrid (and I devoted several years of my life to designing and promoting one) and I think that owning a Volt is just a no-brainer. For me, it is electric virtually all the time, it was cheap to buy (I bought my 2014 with a full year warranty (certified pre-owned -- even the tires were brand new) for less than the price of the most basic new Honda Civic. If you buy a Volt, and never plug it in, it still gets very good fuel efficiency. If you do plug it in, it is fabulously cheap to operate. It's fast, handles surprisingly well for an American car, has loads of do-dads for those who like that stuff... but still, the far more expensive Tesla sells better, despite the fact that Teslas occasionally need to be towed home or to a charging station.

I helped to launch a new Volvo SUV a long while back. At that time, in the minds of marketers, Volvo owners were "We" people. BMW owners were "Me" people. Mercedes owners were "Us" people. They had loads of data to back that up. At the time, the entry level models were interchangeable from an engineering perspective (Identical electronically limited tops speeds, very similar skid pad test results, etc), but what people thought they were saying about themselves when they made the purchase was very different. You could rebadge a Volvo, give it to a BMW driver, saying that it is the next model out, and he would swear that only BMW could make such a wonderful, responsive, flingable, car.

I don't say any of this to be discouraging. Your idea is a very good one in my view. You can probably come up with a rock solid prototype on your own dollar. But before thinking about commercializing, do some serious market research and business planning. That may point to a lower volume that you would hope for, (therefore a higher price) but planning for that can be the difference between a viable business and a failure.

Torquedos are hideously expensive in my view. They are glorified trolling motors. But I think the company is probably successful... not because of good engineering, but because of good marketing, nice design aesthetics, and market planning: the astronomical price enters into that.

I am sure that you can build this and it will work at least as well as you have planned. My only caution is to try to make your market research and business planning as rock solid as you can.

You may be aware, by the way, that the Thunderstruck motors are from the lineage of the Briggs and Stratton electric motor from 16 years ago -- same designer. B&S, even with their millions and a rock-solid motor at a reasonable price, were not able to make it work, commercially.

[john manning]

I have been working on this idea during my spare time over the past year. I have the advantage of owning an engineering business which has a motor winding shop.

My tests to date (all tank tests using fixed pitch marine propellers) have shown that an electric motor with 25% of the power of a fuel engine can turn the same propeller at the same speed. Those tests used a 1:1 right angle drive which would have consumed some energy.

Maximising the efficiency of the electric drive means designing it to run at one speed. A motor is then designed to run at that speed. The speed the propeller turns. This removes the need for a gearbox.

When you look into where the energy goes burning diesel in an engine you find that 35% is heat, 15 - 25% is used by the gearbox and bearings, as much as 25 - 35% can be lost in the internal loads of the engine (this is often because the engine has to be run 2 or 3 times faster than the propeller to produce the total power required). About 10% is used as torque to turn the propeller.

An electric motor running at its design speed is about 96% efficient.

So the best way to use an electric motor is to know the propeller to be used and design a motor to spin it at the speed which gives you the hull speed required. ie. Everything starts with choosing the right propeller for the hull and speed required.

The next step is determining how to provide power for that electric motor. Battery technology is not good enough yet to provide significant storage. Solar cells are improving but are not yet enough. About 10 years ago there was some work done on methanol fuel cells but again not enough energy for high current output needed by motors.

Many people dismiss using generators. Some say that if you burn diesel in a generator then you will not make any savings. They will tell you that burning a fuel achieves the same output however it is converted to motion. If you hear that ask them to explain how you can ride a bicycle faster than you can run.

Diesel electric is the current real alternative for long term electric drives on yachts. That is why it is still regularly used in ships. My tank tests to date indicate I will get a 30% fuel saving. I hope to have my unit installed on my yacht in about 1 year.

[carstendenmark]

Hi, John, nice input !

If I want to make a direct drive, the rpm of the motor would be rather low then.
Max. 1200 rpm for my hull speed.
Even lower, if mounted with a bigger prop.

Most electromotors spin at much higher rev's, thus the need for a reduction by belt or gear.
A such low revving motors available (rating 12-20 KW, 48/96V) or do I need a shop like yours to make one for me ?

[Ericson38]

100 gallons of diesel has just over 4 million Watt hours of energy. With a 25% overall efficiency (thermal & mechanical) that 100 gallons has 1 million Watt hours. That's for 322 kg of mass. So the net extractable energy density in Watt hours/kg = 3105.

The best EV batteries are in the 260-270 range in 2020.

So that means diesel is 11 times as energy dense currently.

Over 10K engine hours, at 1.5 gal/per hour cruising at 6kts, you would consume 6667 gallons of fuel and motor 60K nautical miles. At $3.00 a gallon, you would spend $20K.

[john manning]

Originally Posted by carstendenmark

Hi, John, nice input !

If I want to make a direct drive, the rpm of the motor would be rather low then.
Max. 1200 rpm for my hull speed.
Even lower, if mounted with a bigger prop.

Most electromotors spin at much higher rev's, thus the need for a reduction by belt or gear.
A such low revving motors available (rating 12-20 KW, 48/96V) or do I need a shop like yours to make one for me ?

Motors can be designed to run (optimally) at just about any speed. This is sometimes achieved by designing a matching power supply.

There are standard speeds for AC motors, 650rpm 800rpm, 1000rpm, 1500rpm and 2850rpm for 50Hz power and approx 20% faster when used with 60Hz power. DC motors are often designed to run at similar speeds. However DC motor speed is more variable and the types of motor design more variable as well.

The problem of getting the right speed of DC motor is usually one of price not availability. If the motor speed has to be changed a bit then gearboxes are not the solution.

The problem running a motor at a speed other than its design speed is loss of torque. Modern frequency controllers on AC motors provide good retention of torque down to about 40% of design motor speed. DC motors were the industry choice for variable speed motors because they were better at maintaining torque at different speeds but that situation has now reversed. AC is just as good and cheaper.

So gearboxes can be replaced by speed controllers in most situations. There is however an efficiency loss. Instead of having a 96% efficient motor you will probably have an 80% efficient motor. (NB. A gearbox will probably take away as much or more of your motor power.)

My choice for a drive is a 400V AC motor. That is probably going to get people excited about electrical safety at sea. Part of my business is marine engineering including electrical work. 400 - 500V AC is common on ships and the last diesel electric drive we worked on was a 550V DC drive. If you poke around in a Toyota Prius hybrid drive you can find voltages up to 620V.