Ideal Generator?

[Dockhead]

Originally Posted by valhalla360

I'm aware of heavy duty alternators but a little rube goldberg for ongoing generator style consumption . . .

Why "rube goldberg"? They are specifically designed for continuous, bulk power production.

I've used the one in my present boat to run heavy consumers such as a washer/dryer, and even a 1.5kW immersion heater, via an inverter. Works great.

I also have a heavy duty generator, but heavy duty alternators are really attractive because it is so simple and easy to repair, and so easy to swap out. Remember the task here is to design a boat which has systems which are are robust as possible, for cruising in remote areas.

[DotDun]

Originally Posted by Agility

Best generator is no generator.

Solar array, high output alternator(s), water generator. You can have electric galley. Be mostly diesel independent except for docking. Then you can use your A/C.


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Originally Posted by mcarling

Please read again what Agility wrote.

"... mostly diesel independent ..." not "... absolutely diesel independent ..." (emphasis added)

I did read it more than once. He implies that diesel is required only for docking.

My issue is with the marketing tactics. Reality is that solar will NOT support an electric galley on any common cruising boat. I'll leave alone the fact that cooking with electric is terribly inefficient when you have to generate electricity using diesel.

I love solar as much as anyone, but overselling it's capability on a common cruising boat doesn't help the discussion.

[brianlara 3]

Originally Posted by stefano_ita

QUOTE 100%

Welcome back Steph.

[valhalla360]

Originally Posted by Dockhead

Why "rube goldberg"? They are specifically designed for continuous, bulk power production.

I've used the one in my present boat to run heavy consumers such as a washer/dryer, and even a 1.5kW immersion heater, via an inverter. Works great.

I also have a heavy duty generator, but heavy duty alternators are really attractive because it is so simple and easy to repair, and so easy to swap out. Remember the task here is to design a boat which has systems which are are robust as possible, for cruising in remote areas.

Because rather than pulling power off the crankshaft where the engine is designed to produce power, you using pulleys and belts. Yeah, it can work but engines are generally only designed to have a small percentage of thier power pulled off from the front belts. If you have a 20hp engine and you hook up 4 300amp alternators, I would expect issues with the belt/pulley system.

I suppose if you paired the alternaters so that the side stress on the main pulley is balanced it would largely cancel out but just not a clean design, hence rube goldberg-ish.

Then again we may need to reset to your design goals as I wandered into a twin engine diesel/electric drivetrain that could also cover house loads efficently.

[mcarling]

Originally Posted by DotDun

He implies that diesel is required only for docking.

I can see how one might infer that, but it is not implied by what Agility wrote. The literal meaning of his sentence is that in the non-docking case one can be "mostly diesel independent". The sentence makes no claim whatsoever for the docking case.

[a64pilot]

I think, unless mistaken that the idea was to drive these monstrous, multiple alts off a jackshaft?

[Dockhead]

Originally Posted by valhalla360

Because rather than pulling power off the crankshaft where the engine is designed to produce power, you using pulleys and belts. Yeah, it can work but engines are generally only designed to have a small percentage of thier power pulled off from the front belts. If you have a 20hp engine and you hook up 4 300amp alternators, I would expect issues with the belt/pulley system.

I suppose if you paired the alternaters so that the side stress on the main pulley is balanced it would largely cancel out but just not a clean design, hence rube goldberg-ish.

Then again we may need to reset to your design goals as I wandered into a twin engine diesel/electric drivetrain that could also cover house loads efficently.

OK, I see what you mean.

My idea (as A64 pointed out) was to use a jackshaft for the generator, not to drive the alternators off the front pulley.

If the generator is not used for backup propulsion, the alts can be driven off the flywheel end.

I think a jackshaft would be very simple and elegant, designed by a proper engineer with a flex coupling and robust bearings.

The main engine might also have a pair of school bus alts, in this case "rube goldberged" on opposite sides of the front pulley, but this is not primary power generation.

If budget were no object,

[a64pilot]

I'd even look at the possibility of a PTO, I don't believe they are at all uncommon for Commercial boats, usually to run a Hydraulic pump for winches etc. One advantage of a PTO is of course it isn't rotating until you engage it.
One reason I like hydraulics over electric is size, a 25 HP or so hydraulic motor is a tiny thing when compared to a similarly sized electric motor.
We had two hydraulic pumps on the Helicopter that I used to fly that ran everything, including weapons systems, they were the size of your fist.

[Pete7]

Originally Posted by Dockhead

By the way, my idea of having backup propulsion from the generator engine was discounted by most in this thread, for good reasons I guess.

But how about something like this:

Propulsion

There's a boat on the hard at Cowes with this system, and it's used on top racing boats like Wild Oats and Rambler.

I'm sure this particular system is unaffordable for a backup propulsion on a cruising boat, but nice to fantasize, isn't it? It's a very cool system.

If this is unaffordable then a home brew version could be achieved using a Lancing stern drive mounted on a hinge in a water chest with a plate underneath to provide a smooth flow of water when its closed up.

http://www.lancingmarine.com/databoo.../lmtransom.pdf

[Agility]

Originally Posted by DotDun

My issue is with the marketing tactics. Reality is that solar will NOT support an electric galley on any common cruising boat. I'll leave alone the fact that cooking with electric is terribly inefficient when you have to generate electricity using diesel.

I love solar as much as anyone, but overselling it's capability on a common cruising boat doesn't help the discussion.

Ok, so on a common cruising boat and normal electric galley I'd agree.

With a catamaran and LifePo batteries a KW of solar and induction cooktop I think you'd be OK. Underway you'd need a water generator to keep up with the autopilot/radar/etc. In you use too much energy or no sun, use two Balmar 165 Amp AT-Series alternators (Dual 1/2" vee, serpentine) to top off batteries.

I'll be living with this configuration soon and will let you know if it does't meet our needs.

I do carry propane and two gas burners along with a gas oven in case this doesn't meet our needs or in case we loose electricity. I would have used a convection microwave but wife didn't like that and it required more inverter and more battery so I kept it (sort of) simpler.

[mcarling]

Unless one is cooking for a small army, the time an induction cooktop is running is not going to result in a huge addition to one's electricity consumption. With a kilowatt of solar and sufficient LiFePO4 batteries, I think you should be in good shape. I would love to never carry propane again.

[a64pilot]

I believe an induction cooktop is a big user of power, on par with heating water?
I believe turning anything into heat is very energy intensive, just propane and other normal heating fuels generate enormous amounts of heat. Heating anything would be my last choice for electrical power, have to have quite an excess amount available for that to be logical.


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[mcarling]

Originally Posted by a64pilot

I believe an induction cooktop is a big user of power, on par with heating water?
I believe turning anything into heat is very energy intensive, just propane and other normal heating fuels generate enormous amounts of heat. Heating anything would be my last choice for electrical power, have to have quite an excess amount available for that to be logical.

Heating anything for ten hours per day would be a huge and usually insurmountable burden on a boat's DC electrical system. Ten minutes a day is not a major burden with 1000 watts of solar and LiFePO4 batteries. I would rather carry what you call an "excess" of solar capacity and LeFePO4 capacity than carry propane. Compared to electric propulsion, electric cooking consumes negligible electricity and there are people making electric propulsion work, though the compromises required for electric propulsion are not for everyone.

[a64pilot]

If I had to guess two meals a day amount to at least an hour of cooking total? And more if we bake. But I am not the primary cook, so that is a guess but I'd think a cooktop would pull about 1500W?
If 1500W is correct and if it's a total of one hour a day, then that is 115 AH assuming a bank voltage of 13V.
Now math is not my strong point and I am bad about misplacing decimals, so check my numbers.
I think a cooktop is a metric butt load of power, great if you have it.


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[mcarling]

Originally Posted by a64pilot

If I had to guess two meals a day amount to at least an hour of cooking total?

Your eating habits may be very different from mine (I'm vegan) but I'm sure I've never done 60 minutes of cooking per week, let alone per day, on land or at sea. I'm hard pressed to think of anything I've ever cooked at sea that required more than five minutes. Perhaps I'm a lazy cook.

If you spend an hour a day cooking (I'm still trying to wrap my head around that), then electric cooking would consume a large fraction of what a KW of solar would produce. I guess I would then recommend bumping that up to 1200 to 1500 watts of peak solar capacity.

Originally Posted by a64pilot

And more if we bake.

Were we talking about induction cooktops?