Viability of electric only propulsion in 2018 - is there a good option after all?

[Augi]

Originally Posted by BigBeakie

As I have committed to previously, when we are in sea trails with our OV system, I will film regen in real time, without any pauses so you know there is not any tricky editing taking place, (because I just KNOW that will be your cop out) showing boatspeed without regen, and then switch it on. I'll do that in as steady a wind situation as I can, and I'll switch it on and off several times.

I think that will deal with this particular issue.

Hi BigBeakie,

Wouldn't a parallel hybrid set up be better with direct drive instead of sail drive with motor and standard diesel mounted on the same drive shaft?

Did you considered that option when designing your new ride? If yes why did you select what you selected versus the option described above?

In what is going on your new boat is there a generator for each motor or just 1 generator for both motors?

Can the generator(s) run the motors directly or are the motors always run by the batteries?

What is the range supposed to be in flat water, with no wind and with no current for your new boat starting with full charge on the batteries and full tank of diesel for the generator(s)?

What is the approx. total weight difference between the EP solution you are putting on your boat versus with no EP solution for example similar to what is usually used on performance Cats like Outremer where no generator is installed(just solar and hydro-generator), and the engines are run 1 hour or so a day, if the batteries needed to be charged?

Why has an thorough, independent side by side test not been commissioned by OV or is one in the work? That combined with a one to two years of maintenance records and performance records of of a number of EP equipped boats circumnavigating will be the proof of the pudding?

I think it is great what you are doing. Thank god for the early adopters like you. Most of us do not have the resources, time or opportunity to do what you are doing?For sure EP is the future

[Dockhead]

Originally Posted by BigBeakie

.. . . If you have a cat that can sail at 8 kts, you could be generating about 3kW of charging. Plenty of cats can cruise more towards 10 kts & then we're talking about double that again. So now it's like you are cruising with a 6kW genset running full time!. . .

Is there any documentation for a claim like this?

If it's true, then regeneration offers possibilities that for some reason no one is exploiting. Compare to GrowleyMonster's comments, which seem to contradict this.

I don't know what the efficiency of regeneration is in the whole chain from resistance to power, but if it's even say 50% efficient, then to generate 3kW from regeneration, it would be like having a 10hp motor running wide open in reverse. I wonder what conditions do you need, to maintain 8 knots with a 10hp motor running in reverse?

Sounds pretty hard to believe to me, but I would love to be proven wrong -- just with facts and measurements, not advertising material, please.


And if there is a device I can buy which can generate a realistic 3kW (or even a realistic 1kW) of power when I'm sailing at 8 knots, I'll buy it!! You don't need to be using electric propulsion, to be interested in that. The market would be huge . ..

[a64pilot]

3 kw converts to about 4 HP I think.
So if we forget the prop efficiency, cause a prop is both used for generating power and in the motor case, for developing thrust, then it’s like having a 4 HP high thrust motor in full reverse when sailing.
I say high thrust to try to even out the prop diameters, although I’m sure the one in regeneration is larger and therefore more efficient at eight kts. But let’s give him all the rounding errors etc.

Another way is to determine the power required to sail at that speed, and then reduce that number by 4 HP to get your new speed. That is assuming you regen at 100% efficiency tough but ought to give you a decent guess.

The reason regenerative forces are used to slow down a hybrid automobile and even trains, is because it can be a tremendous force.

And at one point we were discussing regen of 6 KW so double the resistance.

And no, I have not watched the video, and probably won’t.
Call me an ignorant old fool if you will, but I don’t believe in free lunches.

Look if you could get anything even close to those regen numbers without hugely slowing the Boat, then I’m in, just for the regen, heck with the rest. With 3 KW, I could run my whole boat, both air conditioners, charge batteries the whole shebang. Turn off one AC and make water.
How come we don’t all have regen if you can get that kind of power?

[Seman]

I just over 4 years we have covered approx. 30 000 nm. we have an each of our 30 hp motors 890 hr, having consumed around 3500 lt diesel and maybe 200lt Petrol for our Honda 1000 W, to help charging the batteries when our 1000 W solar was not performing. Would a Hybrid system be an economic advantage? I think not.

[BigBeakie]

Augi,

I answered your post with quite a bit of info, but the CF session crashed and it was lost, apparently. So I'll answer later, just wanted to let you know.

[Dockhead]

Originally Posted by a64pilot

3 kw converts to about 4 HP I think.
So if we forget the prop efficiency, cause a prop is both used for generating power and in the motor case, for developing thrust, then it’s like having a 4 HP high thrust motor in full reverse when sailing.
I say high thrust to try to even out the prop diameters, although I’m sure the one in regeneration is larger and therefore more efficient at eight kts. But let’s give him all the rounding errors etc.

But no, it doesn't work like that. The efficiency losses work in different directions. So 4 hp put through a gearbox then through a prop into the water will put what -- 2 hp into the water? Maximum! Probably less.

So to get those 4 hp all the way back via prop etc., surely will require at least 8 hp in the water. So that would be a 16 horsepower outboard generating the same thrust at WOT.

I'm guessing at the efficiencies, but that's how it work.

[martinwinlow]

Originally Posted by billknny

You are proposing to take diesel fuel and converting it to mechanical energy, then into electrical energy, then store that energy, then pull it out of storage, convert its voltage and or frequency, and then convert it back to mechanical energy...

And you honestly believe that will be more efficient than taking diesel fuel and converting it to mechanical energy?

I am guessing you are not an engineer...

I'm guessing you aren't either because that's exactly what every hybrid vehicle (an ever-expanding section of the automotive population) on our roads do not to mention most trains, in Europe at least, too, but they usually manage to do away with the first bit by having a ready supply of electricity wherever they go.

In fact, the reason Big Auto is getting away with conning the car owner/taxpayer (with the connivance of Big Oil and their political bed-fellows) into buying hybrids over EVs, boils down to the simple fact that a hybrid motive system (be-it car, boat, train or anything else - aircraft soon, too!) can operate at anything from 10% to 25% better efficiency simply because whenever the engine is run it is run at it's most efficient speed. I suppose a well-designed boat would have an engine and gearbox set up to give an optimum range per time.gallon and thus the main advantage of the hybrid set up is watered-down but not lost completely.

One issue that *is* missing from the OP's thought-train is the weight of 4 Tesla battery packs which would equate to about 400kg/840lb - a not inconsiderable weight and I would suggest you would not get both a battery that size *and* a standard fuel tank in your boat.

So ditch the diesel completely (have a *small* gen-set if you *really* must - LPG?) and go with the 200nm battery.

[john61ct]

Not to mention even 99% of engineers couldn't set up Tesla paks to be safe enough for a boat.

Check with insurance co's if you doubt it.

[rcpmac]

Originally Posted by CaptainIglo

Thanks for your reply. Glad to finally hear from someone which actual (almost) first hand experience!

Frankly, I, as a cruiser forum newbie, was a bit disheartened by the rough and dismissive tone of many replies. It seems clear to me that this is the future, even if we’re still a couple of iterations away from electric being competitive with diesel for sail boats. I’m guessing in 10 years time no one will want to buy a new Diesel engine. After all it’s all a matter of energy density in batteries and that (together with efficiency of solar) is increasing each year. For sure solar on a boat is unlikely to ever be sufficient as the sole source for charging to provide electric propulsion but it still seems to me that a combination of a hybrid propulsion/ generator like the ocean volt, solar panels and a backup diesel generator has real potential in the future.

The electric car revolution is well underway and that means the cost of batteries will drastically come down in the next years then it’s a no brainer.

You are disappointed that people are dismissing an idea that over and over again has shown to be not ready for realistic implementation but in the same breath acknowledge that it is at least a decade off. (Not even sure how you come to that conclusion beyond wishful speculation. Well here is reality. I know someone with an electrified C&C 34. Beautiful installation with large battery banks and quiet clean motoring. He can't sell it because the range makes it useless even in puget sound.

[john61ct]

Even a propane fired genset would require a lot of work and meticulously checklisted safety process to be made safe for most boats.

Purpose-designed from scratch, sure.

[Adelie]

Originally Posted by john61ct

Even a propane fired genset would require a lot of work and meticulously checklisted safety process to be made safe for most boats.

Purpose-designed from scratch, sure.

Why would a propane engine need to be meticulously checklisted? I see plenty of folk fire up their propane stoves without using a checklist.

[john61ct]

I mean ongoing regular inspections, leak tests etc.

Boats blow up all the time from propane leaks settling in the bilge, including ones owned by the Navy.

I have yet to hear of anyone using propane as a propulsion fuel.

Lots heavier than diesel per energy stored, even without the much heavier tanks required.

[valhalla360]

Originally Posted by Jim Cate

Yep, 64, I did do that, and it was quite successful. That boat did a lot of miles at around 6 knots, and at that speed my homebrew towing gen put out around 10 amps. At 7 knots it was substantially higher, but it would jump out of the water frequently and tie the towing rope in knots, rendering it useless. None the less, it supplied all our domestic power needs. Quite useful, but clearly not capable of recharging a depleted propulsion bank.

If you do a ton of offshore miles, that may be helpful for house loads but for propulsion...

10amps at 12v is only 120watts.

Electric motors running at 12kw will require 100hrs of generation at 10amps to put that into the batteries (Assuming an unrealistic 100% efficiency).

If you start talking about more typical coastal cruising patterns where the motors come into play more, you will be lucky to get 3-4hrs of towing in a day (nothing at anchor or in a slip)...so the vast majority of cruising boats don't bother with them.

House loads and propulsion are totally different animals.

[valhalla360]

If you really want to play with electric, the one option I can see working:

Catamaran with a slightly larger diesel in one hull and a smaller electric motor with smaller generator in the other hull and a moderate solar array/battery bank:
- You can charge the battery bank from shore power or wait on the solar array.
- For short in and and out of harbor in moderate conditions, you could use the electric motor. It also gives you instant thrust available.
- Most larger cats already have a generator, so the same generator could be used.
- When you need to make miles, you crank up the big diesel.
- In an emergency, you can run both diesel and electric as long as fuel holds out (with generator keeping the batteries up).

This really makes sense for a new boat or if the old engines are dead and being replaced anyway.

If you want to be "ecofriendly", you can limit yourself as much as possible to the electric propulsion but if safety is at stake, you have options.

Cost shouldn't be much more than 2 diesels & a generator.

[john61ct]

Yes. There could just be one big ICE with a pair of massive alts delivering say 30kW of high voltage.

For redundancy, two identical setups delivering both / either propulsion and / or electricity.

Then start off with just one electric propulsion engine, only add the second one if you decide that makes sense.

Never mind about much battery storage until the higher density future arrives, just what you need for a LFP House bank.

Any alternative energy sources can be added if you want to fool your friends into thinking you're green, but really will be redundant, just window dressing.