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Old 21-02-2015, 17:39   #1
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Propane generator on board

I'm looking at repowering with electric. Another sailor mentioned propane generators as a great clean way to rejuice the battery bank. Anyone have any thoughts, suggestions or comments before I get out the weathered check book?
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Old 21-02-2015, 17:46   #2
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Re: Propane generator on board

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I'm looking at repowering with electric. Another sailor mentioned propane generators as a great clean way to rejuice the battery bank. Anyone have any thoughts, suggestions or comments before I get out the weathered check book?
Yes. Make sure the installation is 100% ABYC compliant.
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Old 21-02-2015, 18:22   #3
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Re: Propane generator on board

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...Another sailor mentioned propane generators as a great clean way to rejuice the battery bank...
If they were that great you'd see them on many yachts. Diesel is safer and cheaper.
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Old 21-02-2015, 18:37   #4
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Re: Propane generator on board

Propane isn't safe in a closed space like a hull. Propane is heavy so any leak settles in the bilge and waits for a spark. With a generator and the vibration, I would say it's very dangerous. Probably more than gasoline.
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Old 22-02-2015, 03:38   #5
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Re: Propane generator on board

I have one quote for a propane powered fuel cell: 1kwh 40,000 euros
It extracts the hydrogen from the propane and then creates electricity in a fuel cell (I think) 1kW REFORMATE FC - Tropical S.A. | Fuel Cell and Hydrogen Technology

Might explain why you don't see many on boats.
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Old 22-02-2015, 03:49   #6
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Re: Propane generator on board

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Originally Posted by Kalinowski View Post
I'm looking at repowering with electric. Another sailor mentioned propane generators as a great clean way to rejuice the battery bank. Anyone have any thoughts, suggestions or comments before I get out the weathered check book?
You mean ditching the diesel main engine and going to electric hybrid power?

I agree with the posters above that propane is dangerous inside the main hull volume. A propane powered IC engine has many more potential leak points than a propane stove. Besides that, where will you get the fuel? I've never seen bulk propane sold on the quayside anywhere.

People who do hybrid power use diesel generators. There are a few guys on here who have done it; check the archives. It's a serious project -- are you up for it? If you are not an enthusiastic tinkerer and excellent engineer, then plain conventional diesel power with normal direct drive is probably going to be vastly cheaper and easier.
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Old 22-02-2015, 10:11   #7
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Re: Propane generator on board

The OP didn't provide details. Perhaps he is thinking of a Honda generator converted to propane and installed and operated above deck.

No matter how you slice it, burning fuel to make electricity to propel a boat with an electric motor comes out on the short end of efficiency. Connecting the engine directly to the propeller cuts out the inefficiencies of the conversion process.
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Old 22-02-2015, 14:57   #8
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Re: Propane generator on board

Those tanks also have a weight are big and bulky. Specially in marine eviroment they have to be inspected on a regular basis.
Adding to existing energy systems ? I donīt think thatīs a good idear. Every energy source on board needs itīs own control system wiring etc, storage system, add on charging / filling etc + +++plus another baby to watch and maintain.
Also itīs more complicated to get gas then diesel.

The only thing I could think of would be using a generator to drive electric propulsion. Electric motor has a lot of torque is smaller and a lot easier to maintain...less moving parts and no gear box = less spare parts.
All of that should also result in less costs.......???
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Old 22-02-2015, 15:59   #9
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Re: Propane generator on board

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........ The only thing I could think of would be using a generator to drive electric propulsion. Electric motor has a lot of torque is smaller and a lot easier to maintain...less moving parts and no gear box = less spare parts.
All of that should also result in less costs.......???
Think about that a minute. Sure the electric motor is simpler than a diesel engine but if you have to have a diesel engine and generator to provide electricity to the motor, it's more complicated, not less.
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Old 23-02-2015, 06:14   #10
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Re: Propane generator on board

With an understanding of the dangers, and a careful installation, I think that a propane generator could be at least as safe as a gasoline generator (which many carry).

To me the main issue would be the volume of propane required. Propane is not as efficient an energy store as diesel. You need more of it. A lot more. I think that if you look into exactly how much a propane generator consumes, how much you would need to run it, and then do the math, you will find that you need to dedicate a VERY LARGE amount of space to storing propane. And then, as mentioned, how are you going to refuel?
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Old 23-02-2015, 06:54   #11
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Re: Propane generator on board

If you really want to have an electric drive...
Phasor made a 2500 watt diesel generator for boats. You may want to check it out.
Low RPM, low noise, compact.
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Old 23-02-2015, 09:43   #12
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Re: Propane generator on board

Rhasor looks like a nice unit to get in tight spaces for the production even so very small but at least itīs low RPM and Kubota seems like a reliable name.

Have no experience with electro drive and until for construction of a new boat I donīt see it practical to convert a diesel powered boat to electro drive.
But I see some positive aspects for boat building to it.
For example the electrodrive has a very low foot print and can fit any where in the bilge. Also I have seen units that are outside of the hull for the cooling of the motor. The unit is mounted on a shaft that goes on or through the hull that also serves as very effective steering. These units also can be retracted while not in use wich would make them less succeptable to plant growth etc. and all the hassle of maintanance that comes with it.
I think one of the biggest atvantages is the gain of the space of the engine room because the generator can be on any conveniant location on the boat. That should also have positive features on noise and vibration levels.
That should open up a total new spectrum in space lay out on boats

Another positive factor is they bring the max torque right from the start and through out the whole spec of RPM wich should be very positive for prop design. All of that should lead to a more effecient use of KW produced from the diesel generator.
As far as control of DC or AC motors, I beleave there has been made lots of progress and I donīt see this an issue at all
Another thing I really like with a generator as prime source everything on board would run on electricity NO more gas bottles wich is very clean and the instalation is very easy. With a right sized Lithium pack I also beleave the generator would not have to run all the time.
For safety, well just another small unit that is also used if more power is requiered for peaks
In case of service the whole and compact unit is just disconected and hauled out to any conveniant shop / location and nothing of the marine price mark ups.
In case of a new design I could see myself seriously considering
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Old 23-02-2015, 09:54   #13
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Re: Propane generator on board

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Originally Posted by warrior 90 View Post
Those tanks also have a weight are big and bulky. Specially in marine eviroment they have to be inspected on a regular basis.
Adding to existing energy systems ? I donīt think thatīs a good idear. Every energy source on board needs itīs own control system wiring etc, storage system, add on charging / filling etc + +++plus another baby to watch and maintain.
Also itīs more complicated to get gas then diesel.
And you can't have those tanks in the main hull volume. Where will you put the propane tank? And where will you buy propane in bulk? And why would you bother when diesel fuel is (a) much higher power density than propane; (b) much safer to use and store; (c) much easier to store; and (d) much more readily available.
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Old 23-02-2015, 10:13   #14
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Re: Propane generator on board

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. . . With a right sized Lithium pack I also beleave the generator would not have to run all the time.
For safety, well just another small unit that is also used if more power is requiered for peaks
. . .
The size of the battery bank has nothing to do with how much the generator will have to run -- that is determined by how much power is consumed versus the output of the generator (subject to inefficiencies of the charge process and battery acceptance rate).

If you only need maximum power in relatively intermittent bursts, then you can "peak shave" with the batteries, which will add to efficiency, allowing you to use a smaller generator than you would have had to have main engine, but if the generator is undersized compared to average power consumed, then you will have problems, even with a big battery bank.

And some safety situations -- like clawing off a lee shore in a storm -- may demand maximum power or a high power output for a sustained period of time. Will the system handle that? It can be really hard to sail off a lee shore in a real storm -- sometimes your engine can be a life and death issue.
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Old 23-02-2015, 12:45   #15
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Re: Propane generator on board

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The size of the battery bank has nothing to do with how much the generator will have to run -- that is determined by how much power is consumed versus the output of the generator (subject to inefficiencies of the charge process and battery acceptance rate).

If you only need maximum power in relatively intermittent bursts, then you can "peak shave" with the batteries, which will add to efficiency, allowing you to use a smaller generator than you would have had to have main engine, but if the generator is undersized compared to average power consumed, then you will have problems, even with a big battery bank.

And some safety situations -- like clawing off a lee shore in a storm -- may demand maximum power or a high power output for a sustained period of time. Will the system handle that? It can be really hard to sail off a lee shore in a real storm -- sometimes your engine can be a life and death issue.
Certainly all those factors need to be balanced. I think here also the cruising range would have to be considered. Have seen set ups on sailing cats with 2 electrodrives, 2 equal generators and 1 battery bank. Made a good impression on me. Have a look at this system
New design possibilities
But I think as the size of the power requiered goes up things look different.
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