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

[john61ct]

And be required in some contexts for safety.

Yes greater skills can reduce that need, but to some extent that's also relying on luck more than modern sailors consider sensible.

[DotDun]

Originally Posted by Capt Gill

DotDun:
"Nothing is free."

Not exactly true, e.g., wind, currents & tide levels, solar are free; it's the harnessing of this energy that costs, some more or less than others.
Be wary of absolutes.

Typically sailors want to do more with the wind than just look at it...

[KTP]

Originally Posted by DotDun

That’s not what you said. You stated at a slow speed of 5kts, which unless your hull speed is 5kts, regen is taking speed away from the boat. I agree that when the sails are producing more power than the hull can use that regen makes sense, but in lighter winds, regen will cost in speed.

No, you said turn off regen and you would be doing 7 knots instead of 5 knots. Our hull speed is 6.87 knots so if we were doing 7 knots it would be pretty good wind and really starting to push a large volume of water on the bow, significantly more drag than would be seen by the regen prop.

I do think we can agree that there is a lot of drag in light wind.

[valhalla360]

Originally Posted by AKA-None

So is there any reason it must be either or. It would seem to me that a hunted approach as stated earlier might be a good next step in evolution. Main propulsion is sail, secondary for maneuvering is electric and if a big or sustained push is required then internal combustion. Realistically how many hours of travel do most people do with their engines vs sails? And yes many people use their sails as decoration rather than propulsion.

I think the problem is market based. These discussion are often focused on cruisers who are far outside the normal market.

Yes, there is the rare oceanalexander who is willing to wait 3 days for the right conditions to make the next run or use a sculling oar but when you look at new boat buyers (the ones really driving the market), the sailing purists who can use electric as a viable option are the rarity.

I would bet your average 30-50' cruising sailboat spends 70-90% of the time under diesel power (at least based on what I see on the water). Sailing is limited mostly to day sails where you just pick a direction based on the wind and rare travel days when the wind happens to be from the right direction.

For electric propulsion to become mainstream, it really needs to address this use case. Otherwise it will remain a DIY niche.

I've posted a few times that I think a catamaran with a slightly up-sized (maybe 20% larger) diesel in one hull and small electric drivetrain that can be fed from the house generator and small battery bank in the other would be a good 90% solution. If you want fiddle around to maximize efficiency, you can probably get 95% of miles under electric or sail but even with a modest effort, you might get 50-60% under electric/sail. But even if you just don't care, you might cut diesel consumption by 20%. Eliminating one propulsion diesel should cancel out most if not all of the cost of an electric motor and modest battery bank (house generator is typical anyway). The end result is negligible cost difference but no loss in capability.

[GrowleyMonster]

I notice that most of the more vocal proponents and detractors both, of EP and hybrid propulsion, do not have electric boats, and are actively encouraging or discouraging, according to what "side" they have chosen, the use of electric or hybrid drive.


Every system has its drawbacks. Combining more than one, as in the case of a parallel hybrid setup, mitigates most of them, though it does add to complexity and the demand for technical competence in the operator.


Just imagine the world where diesel is the new kid on the block, and solar electric has been king of the hill for the last 100 years. New adapters are going for that new fangled infernal combustion engine. The stick in the mud, old guard, diehard electric guys poke fun at the clanky smoky complicated apparatus and its need for a constant source of that liquid petroleum fuel, and how when you run out of crankcase oil for some reason, it siezes up and dies, demanding a complete rebuild at a cost of $10k or a whole new engine thingie at two or three times that cost. Those who have not yet tried the new thing being the most vocal pro/con drum beaters. Some of the luddites would point out that you have to plan fuel stops, and be watchful of consumption even when the sun is shining brightly, and that without that fuel stuff, the engine is just dead weight, taking up enough room to sleep another crewmember or guest. And oh my, the NOISE! The HEAT! You have a FIRE, or more properly EXPLOSIONS contained within a sealed iron cylinder! And wow, the Rube Goldberg system of crooked drive shaft, connecting rods, wrist pins, piston, piston rings, valves, injectors... compared to a rocket engine it is impossibly complicated and delicate! Liquid cooling? Oh, puh-LEEEEEEZE! I understand that if you just forget to open the seacock you toast the engine in under an hour! And some guys have turbochargers because our perfectly normal atmosphereic pressure isn't GOOD ENOUGH, for the picky diesel motor.



Then there are other guys who will point out that hey, when the sun doesn't shine for weeks on end, the diesel will still run. Regen isn't needed. The fuel in the tank lasts a lot longer than the charge in a bank. You can do without the huge bank of batteries, because after all, air conditioning is just a luxury and Joshua Slocum never whined about not having it, or a refrigerator, or an espresso machine, blah blah blah.


Think about it.

[bluenomads]

Originally Posted by valhalla360

I've posted a few times that I think a catamaran with a slightly up-sized (maybe 20% larger) diesel in one hull and small electric drivetrain that can be fed from the house generator and small battery bank in the other would be a good 90% solution. If you want fiddle around to maximize efficiency, you can probably get 95% of miles under electric or sail but even with a modest effort, you might get 50-60% under electric/sail. But even if you just don't care, you might cut diesel consumption by 20%. Eliminating one propulsion diesel should cancel out most if not all of the cost of an electric motor and modest battery bank (house generator is typical anyway). The end result is negligible cost difference but no loss in capability.

I’ve certainly been listening - what you’ve written is exactly what we are planning. But we’re just starting, with boat purchase underway (survey tomorrow!). Look out for us in six months or more

[valhalla360]

Originally Posted by GrowleyMonster

I notice that most of the more vocal proponents and detractors both, of EP and hybrid propulsion, do not have electric boats, and are actively encouraging or discouraging, according to what "side" they have chosen, the use of electric or hybrid drive.

The problem with this logic is adoption of electric propulsion between proponents and non-proponents logically should be different.

It makes no sense that individuals pointing out the significant fact based limitations would install an electric propulsion system (at least not in any significant numbers). If you eliminate them from the discussion, you wind up a biased discussion where everything looks wonderful and no one points out the problems.

On the other hand, there is a certain amount of truth (though far from 100%) that if the systems are as good as the more ardent proponents claim, they should have converted by now because it is so much better. Not only that, they should be able to present fact based document-able results (both calculations and field measurements).

Otherwise, I agree with your post and love that you provide a more balanced view but it seem's to be the rare individual who commits to these systems and is willing to admit the limitations.

[valhalla360]

Originally Posted by bluenomads

I’ve certainly been listening - what you’ve written is exactly what we are planning. But we’re just starting, with boat purchase underway (survey tomorrow!). Look out for us in six months or more

I would love to hear how this works out.

I've just been doing back of napkin calculations so my specifics power ratings might be off a bit but on the surface it seems like a good step forward until they solve the energy density limitation of batteries.

[CharlieJ]

Stu M: Post 163

Without going into too much detail, the diagram you provided is pretty flawed. That said, it does show an EPM (Emergency Propulsion Motor) collinear with the propulsion shaft. The EPM is powered by the battery bank.

[KTP]

Does anyone make a small air cooled diesel generator maybe slightly bigger than the Honda EU2000i?

We plan to pull the 30 gallon diesel fuel tank from our Pacific Seacraft 34 since we have pulled the Yanmar 3HM35F and don't need the tank (Force 10 stove is propane).

I kind of doubt there is that small of a gen set.

[john61ct]

The little Kubotas are nice.

But only "portable" if you're the Hulk

[CatNewBee]

Originally Posted by KTP

Does anyone make a small air cooled diesel generator maybe slightly bigger than the Honda EU2000i?

We plan to pull the 30 gallon diesel fuel tank from our Pacific Seacraft 34 since we have pulled the Yanmar 3HM35F and don't need the tank (Force 10 stove is propane).

I kind of doubt there is that small of a gen set.

look at EU RV aftermarket supplier, there are generators out there with options for diesel, propane or gas.

https://www.dometic.com/de-de/de/pro...ng/generatoren

[CatNewBee]

https://youtu.be/OZmbtG_bOlQ

[sstuller]

Having dealt with gas and diesel engines for thirty plus years on sailboats I am well aware of the reliability of these beasts. If anyone is telling you about their wonderful reliability he is lying to you. Once you put an infernal combustion engine on your boat it becomes the focal point of all your maintenance. Their demands far outweigh any other equipment on your boat and you will soon find out you have turned into a diesel (or gas) mechanic. Sailing will be forgotten. I came to the conclusion that if I had to put up with a diesel to go sailing, sailing is not worth the trouble.



My only hope if I wanted to go sailing and I needed an auxiliary is an electric motor. My first experiment was with a new $99 Minn Kota on my dink. I lived aboard on a mooring for five months. A 15 watt solar panel kept the battery charged. The Minn Kota ran flawlessly for five months without a hiccup. No gas outboard can match that reliability.



There is now a Torqeedo on my 25' sailboat. There is hope for sailing again.

[valhalla360]

Originally Posted by sstuller

Having dealt with gas and diesel engines for thirty plus years on sailboats I am well aware of the reliability of these beasts. If anyone is telling you about their wonderful reliability he is lying to you. Once you put an infernal combustion engine on your boat it becomes the focal point of all your maintenance. Their demands far outweigh any other equipment on your boat and you will soon find out you have turned into a diesel (or gas) mechanic. Sailing will be forgotten. I came to the conclusion that if I had to put up with a diesel to go sailing, sailing is not worth the trouble.

My only hope if I wanted to go sailing and I needed an auxiliary is an electric motor. My first experiment was with a new $99 Minn Kota on my dink. I lived aboard on a mooring for five months. A 15 watt solar panel kept the battery charged. The Minn Kota ran flawlessly for five months without a hiccup. No gas outboard can match that reliability.

There is now a Torqeedo on my 25' sailboat. There is hope for sailing again.

You are changing one devil for another...nothing more. Now you will be slave to a charging system and batteries.

Then again a bit of melodrama on the effort needed to maintain an engine. For a comparison to your 5month test of a trolling motor, we put a 25hp outboard on our 34' catamaran and over 10yrs and around 8000miles, we did an oil change once or twice a year...otherwise it ran flawlessly.

PS: if a single 15w solar panel keeps the battery charged, you must have a mooring 50' from the dingy dock or you let it charge for days between use. That's only going to generate around 60w-hr per day. The base min kota 30lb thrust model draws around 360w, so your panels can produce around 10min of 30lb thrust per day.