Electric Drive: Who uses it?

[Wayfarer1008]

LOL the guy just turned his boat into a 41 foot Duffy.
Great for cruising the harbor but forget about going anywhere. I've seen people put electric power plants into boats like Santana 30/30's and other old racing boats thinking like they are upgrading the power systems without understanding that weight is the big overlying concern and if its for getting back and fourth into a slip you can do it better with an outboard.
I can understand if the boat is designed from the ground up to be electric but if you want to take all the value and usefulness out of your boat put in an electrical drive.

[storx]

I understand that it doesn't make sense to take out good diesel engines out for electric, but you have to understand that electric motors are far superior to fueled propulsion in the long run.

There are far less moving parts involved in an electric motor to fail and most electric motors are designed for milions of hours of use before needing to be rewound with new wiring and rebalanced.

I was only asking about it because this was a first for me to hear about it in a boat, he claims it works flawless in his boat and gets around using very little diesel. He said he has solar panels mounted on the roof and deck of his boat that charges the battery bank everyday the sun is out, so he can cruise a little on basically solar, then anchor off enjoying the new spot while the solar charges the battery back up. He said he only uses the generator when he is driving further than about 40-50 miles, because then the battery bank is depleted.

I know an electric drive, diesel engine range extender setup can function well because i currently drive a chevy volt, this car is ALWAYS electric driven, the car runs off the batteries tell it runs low, then the gas engine comes on turning another generator head that feeds power directly to the motor controller circuit, so when im cruising down the highway doing 75mph, the gas engine is running only at 855rpms to maintain speeds, so a system has to be properly setup for it to function correctly and a lot of companies out there are still learning this now as the use of this tech is still new...

Reasons i say electric is superior....

My uncle works for union pacific railroad, the trains use 4-8 electric motors to drive the heavy heavy train that has a single diesel engine just barely idling to supply enough power to drive the train. He told me years ago when i bought my electric car that when they converted the trains over, they dropped fuel consumption down to a factor of 1/10th of the diesel they used with just diesel engines driving the trains. The reasons for this is because the diesel engine can be reduced down to near idle speeds and use a turbo sized so it produces near perfect peak torque this low in the rpms, this allows for far less fuel being used. Now he tells me they have dropped the train engines in half, and raised the compression and tolerances to the point that at room temperatures the engine is to tight to turn over, so they have a heating element encasing the bottom of the engine that heats the block up enough to allow the engine to turn over and start, then uses half as much fuel providing the same amount of output in power.

Electric motors are used in heavy equipment all the time now, many of industrial equipment has moved over to this, fork lifts, mining equipment, bulldozers... they are getting far more running hours out of the diesel engine, because its running at a constant speed and load.... and the electric motors are lasting very long and far cheaper to rebuild vs a conventional diesel engine

Electric motors are extremely torquey, so like a 20kw motor may only output 55hp, but around 100lbs of torque..

I am not claiming i am converting a boat over to electric, was just curious because this was the first ive heard of it on a boat and wanted to see what others running it felt.

I did manage to find a handful of trawlers with engine failures for dirt cheap on boat traders, idk its idea i need to read more into.

[StuM]

Originally Posted by Steadman Uhlich

Please take a minute to copy/paste your entire post up above to add it to the following discussion thread I curate

You "curate" a thread? How, pray, do you do that?


Are you permitted to delete, edit, approve other people's posts in that thread?

[Jim Cate]

Oohhh my goodness!!!

Fantasy land...

Jim

(this re Storx's post above)

[a64pilot]

Believe you have some misconceptions about electric motors and hybrid systems.
It is never a more efficient propulsion system than direct drive, however in huge systems, it can be more flexible, there were direct drive Diesel trains, but only a few were ever built, the transmission system was the problem.
Probably the best example of a huge efficient hybrid Diesel electric machine is a monster dragline, but again that is because of the transmission required to do the job is prohibitively massive and an electric motor is better, it’s not more efficient, but it is cheaper to build.
I don’t have a Volt, but doubt that it will maintain a steady 75MPH on level ground at 855 RPM for example.
If it’s like a Prius and I suspect it is, to begin with it’s an Atkinson cycle engine, and then it will be run at full throttle but the engine will be pulled down in RPM to match the power output to the power required. This is a miracle in combustion engine management, not electric power.
There is an operation condition of the Prius where it will make electricity for the electric motor to drive the car, it’s called the heretical mode, because it is less efficient than driving the car directly by the engine, it’s rare that a Prius will go into the heretical mode.


Then I think you have a misunderstanding about Solar, most of us barely get by with the Solar we have running our refrigerators and led lights and not much else, nobody has enough Solar to run an air conditioner for example, much less move a boat.
You would have to have a Solar farm to charge your automobile for example, electric cars do not use less energy, just a different form of energy. They can be more efficient in Urban driving where your often sitting and not moving, and an idling engine is not doing anything but wasting fuel.

[skipmac]

Well, I don't work for the railroad but I did manage to get a degree in electrical engineering and I have run the numbers on electric motors in boats several times and they don't add up.

The biggest hurdle is range.

It would take a barge full of batteries to get more than 30-40 miles under battery power alone.

You would have to completely roof over the boat in solar panels to get enough power to barely putt along in calm conditions.

To get range you have to add a generator. Unless you never motor against the wind or waves (kind of limits your boating options) you will have to add a big IE expensive and heavy generator. Now you have replaced one diesel with another and added more complexity, less efficiency and more cost. Check the price of a 50 HP diesel vs a 35 kW generator then come back and tell us how practical electric looks.

[john61ct]

The HP required to get out of danger sometimes needs to always be available when you need it.

Perfectly feasible as hybrid systems given huge budgets.

Not saving any fuel costs until you get **much** bigger.

[Lost Horizons]

Originally Posted by danielamartindm

What is his rationale for the electric engines over diesel?

It is called freedom. If you are able to use renewable energy (solar/wind/hydro/nuclear), you are no longer tethered to a gas station. For some travellers it is important.

[captmikem]

[QUOTE=storx;2640220he stated he is planning on upgrading the generator to a larger generator in the future, or possibly add an additional 2nd generator onboard for cruising at full speed.[/QUOTE]

So he runs diesels attached to generators to charge batteries to run electrical motors.....

seems like it would be less complex, simpler, and more efficient to just hook shafts and props to the diesels eliminating the weight of the generators, batteries, and electric motors. Simple and easy.

M

[john61ct]

Solar on a practical boat won't supply even 10% of what's needed for propulsion.

Until they make normal behaving sailcloth that produces higher watts-per-sq-meter than current 22% efficient fixed panels, with decades' longevity.

We'll get there, I'm sure long before teleporting, but not in a decade or two.

[StuM]

Originally Posted by Lost Horizons

It is called freedom. If you are able to use renewable energy (solar/wind/hydro/nuclear), you are no longer tethered to a gas station. For some travellers it is important.

But not in the case under discussion. He hasn't gone to renewables - he's just switched a diesel engine for a diesel generator and EP (and is apparently intending to add more diesel generating power).


So the question remains. What is the rationale?

[john61ct]

Some people just like spending their time and money on Science Projects.

More power to them.

As renewables-produced electricity gets more practical in a mobile context, he'll be ready to start (slightly) reducing his diesel burned per mile traveled.

Or perhaps the plan is hopping from marina to marina recharging overnight?

[Lost Horizons]

Originally Posted by john61ct

Solar on a practical boat won't supply even 10% of what's needed for propulsion.

Really? Have you tried to do calculations?

On vast majority of sailboats, engines are used for about 100 hours a year or less producing somewhere around 10 kW. This is 1000 kW*h a year. A refrigerator uses 0.5 to 1 kW*h a day, say around 250 kW*h a year on average. Everything else uses around another 250 kW*h a year or so for a total energy budget of roughly 1500 kW*h a year.

A 1000 W PV battery will generate 1000 to 1500 kW*h a year. So getting close to a 1000 kW*h a year, accounting for charging inefficiencies, is quite possible with a reasonably sized solar panel bank. Add a windmill or another panel ot two and you don’t need to buy fuel at all. Not just for propulsion.

Alternatively, one day in a marina with a 50 A service provides up to 290 kW*h a day. Say, 250 kW*h absorbed accounting for charging inefficiencies. So, 6-12 good days per year in a marina with a Tesla-like battery on board should also suffice for a fossile fuel free life even if you don’t have any generation means. The combination of two should work for most people most of the time.

[Lost Horizons]

Originally Posted by StuM

But not in the case under discussion. He hasn't gone to renewables - he's just switched a diesel engine for a diesel generator and EP (and is apparently intending to add more diesel generating power).

Nobody is perfect.

[valhalla360]

Originally Posted by Lost Horizons

Really? Have you tried to do calculations?

On vast majority of sailboats, engines are used for about 100 hours a year or less producing somewhere around 10 kW. This is 1000 kW*h a year. A refrigerator uses 0.5 to 1 kW*h a day, say around 250 kW*h a year on average. Everything else uses around another 250 kW*h a year or so for a total energy budget of roughly 1500 kW*h a year.

A 1000 W PV battery will generate 1000 to 1500 kW*h a year. So getting close to a 1000 kW*h a year, accounting for charging inefficiencies, is quite possible with a reasonably sized solar panel bank. Add a windmill or another panel ot two and you don’t need to buy fuel at all. Not just for propulsion.

Alternatively, one day in a marina with a 50 A service provides up to 290 kW*h a day. Say, 250 kW*h absorbed accounting for charging inefficiencies. So, 6-12 good days per year in a marina with a Tesla-like battery on board should also suffice for a fossile fuel free life even if you don’t have any generation means. The combination of two should work for most people most of the time.

Give us the assumptions as your numbers don't add up.

10kw of power (even under good conditions would presume a small boat that wouldn't have room for 1000w of solar. Also, unless you have a massive battery bank, you run into issues, where that 100hr of run time per year isn't 1 hr every 3.65 days. so if you are away from the boat for 3 months, much of that solar is lost because the batteries are already full.

So before we look in detail, give us assumptions regarding the boat, use case, location, etc...