Ideal Generator?

[a64pilot]

I'm going out on a limb here, but from an efficiency perspective, the Holy Grail, is direct drive.
Sort of takes us back to dual engines, dual drives.
Beginning to sound a like a production Catamaran? Upsize the alternators and your there?


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[stefano_ita]

Originally Posted by a64pilot

I'm going out on a limb here, but from an efficiency perspective, the Holy Grail, is direct drive.
Sort of takes us back to dual engines, dual drives.
Beginning to sound a like a production Catamaran? Upsize the alternators and your there?


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Yes, like big boat without even reversing gearbox, direct drive and controllable pitch propeller...

Still looking for the most suitable boat for my need (liveaboard at the hook)...
I was valutating catamaran and i'm thinking on how to manage 2 engine...ok using one by one for slow-cruise- motor boating (less fuel consumption), and maybe add a bigger alternator on both engine to have both capable to be used as generator...maybe...but still thinking...

And what if i found a boat that need 2 new boats?...hard to say...maybe right sized engine in one hull , for cruising, and small one with big alternator for emergency engine and genset in the other hull..

Teddydiver, i send you a guest message in your pofile...

[Dockhead]

Originally Posted by a64pilot

I'm going out on a limb here, but from an efficiency perspective, the Holy Grail, is direct drive.
Sort of takes us back to dual engines, dual drives.
Beginning to sound a like a production Catamaran? Upsize the alternators and your there?

Indeed! And I think I mentioned that in the very first post. A cat with school bus alternators on both engines has everything -- redundant propulsion, redundant generation. Motor on one engine for light weather cruising. . . Perfect.

[Dockhead]

And speaking of cats -- a Chris White Atlantic 57, and the Halberg Rassy 64, were the only production boats to survive the last round of thinking about production boats.

The Chris White cat pushes a whole lot of buttons -- very high performance, excellent sheltered helm position, excellent performance upwind, excellent layout, quite good looking for a cat, etc., etc., etc. . . .As does the HR.

But one of the former actually flipped last year -- without sea state as a factor. Just blown over in a violent squall.

And HR are not the quality they used to be, and I think less than my present boat. And no pilothouse, and a few other drawbacks.

So the production boats gradually got crossed off the list.

[stefano_ita]

Originally Posted by Dockhead

Indeed! And I think I mentioned that in the very first post. A cat with school bus alternators on both engines has everything -- redundant propulsion, redundant generation. Motor on one engine for light weather cruising. . . Perfect.

yeah

Even right sized engine with bruntons autoprop for average cruise (it works very well even at low rpm)

a smaller engine/genset with a max prop foldable prop with a bit bigger diameter prop and lower pitch (both engine working togeether for helping in pushing in bad wheater without dradding under sails) that's could be a great deal..

[SVNeko]

Originally Posted by Dockhead

But one of the former actually flipped last year -- without sea state as a factor. Just blown over in a violent squall.

Please specify. I am not aware of this. I do know an A57 named Anna flipped several years ago but believe sea state played a role. But in any event, a high performance catamaran needs to be actively tended. That is their biggest and only drawback.

[Kenomac]

Why not just use a Westerbeke generator which is designed for marine use? That's what we have.

[Dockhead]

Originally Posted by Kenomac

Why not just use a Westerbeke generator which is designed for marine use? That's what we have.

If I go conventional heavy duty AC, it will be Northern Lights, I think. We have a similar unit, a Kohler EFOZ6.5 which has been brilliant. For why I'm consider a DC generator, see first few posts in the thread.

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[stefano_ita]

Originally Posted by Kenomac

Why not just use a Westerbeke generator which is designed for marine use? That's what we have.

That's true but it can be used only for domestic load.

I wouldn't start if for 3 minutes coffe maker...and then switch it off again...

And in case of main engine fail a small 15-20 hp marine engine with a 200 amp alternator cost the same as the westerbeke generator and provide propulsion also...

[a64pilot]

You don't run the gen for three minutes making coffee, you use your inverter for all of those kinds of loads.
You only use the gen for long term high amp loads like air conditioning for example, making water, or charging batteries.
I don't see any need to crank the generator that won't have it running for a couple of hours min.
But since AC to DC are is easily converted now, I don't see any real advantage to a DC gen myself? Turns out my big long term loads are all AC anyway.
Which is not to say School bus alternators, I mean a stand alone unit.
I started out myself thinking huge battery bank, huge inverter and DC gen myself, but ended up with a standard AC gen., much smaller that what is being suggested here, as I have a much smaller boat, and have no desire at all for higher Latitudes.



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[Pete7]

Originally Posted by Dockhead

But one thing to keep in mind is that redundant propulsion achieved this way only backs up the main engine -- not the shaft, prop, etc. It might be simpler, easier, and cheaper just to put in a separate sail drive with folding prop, on the generator engine.

Hmm, no don't like that idea especially if the sail drive is off set to one side (says he specifying someone else's boat). Currently you have one prop protected behind a nice big lump of steel. The keel won't guarantee protection from a lobster pot or ISO container but you stand a chance. Now with sail drives off to one side or twin props operating in high latitudes you are going to find ice and that won't mix well with little props. If the drag problem from the inlet isn't high a waterjet aux might be interesting and could be driven by dino oil, sparks or slippery red stuff.

Pete

[Dockhead]

Originally Posted by Pete7

Hmm, no don't like that idea especially if the sail drive is off set to one side (says he specifying someone else's boat). Currently you have one prop protected behind a nice big lump of steel. The keel won't guarantee protection from a lobster pot or ISO container but you stand a chance. Now with sail drives off to one side or twin props operating in high latitudes you are going to find ice and that won't mix well with little props. If the drag problem from the inlet isn't high a waterjet aux might be interesting and could be driven by dino oil, sparks or slippery red stuff.

Pete

OK, fair enough. Hmm.

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[Dockhead]

Originally Posted by a64pilot

You don't run the gen for three minutes making coffee, you use your inverter for all of those kinds of loads.
You only use the gen for long term high amp loads like air conditioning for example, making water, or charging batteries.
I don't see any need to crank the generator that won't have it running for a couple of hours min.
But since AC to DC are is easily converted now, I don't see any real advantage to a DC gen myself? Turns out my big long term loads are all AC anyway.
Which is not to say School bus alternators, I mean a stand alone unit.
I started out myself thinking huge battery bank, huge inverter and DC gen myself, but ended up with a standard AC gen., much smaller that what is being suggested here, as I have a much smaller boat, and have no desire at all for higher Latitudes.



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Yes - and I'm pretty indifferent to AC vs DC power - both are good for me.

Big advantage of DC in a configuration like this is extreme simplicity and field serviceability of the generator.

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[leftbrainstuff]

Originally Posted by Dockhead

I'm still collecting ideas and thoughts for my next boat, if there ever is one, which will definitely be custom built. I started a thread about it last year which I can't find.

I was reading Noelex's classified ad for his old boat, and among many other excellent features, really liked his generator. It's a standard boat propulsion engine -- so already marinized with standard parts -- a huge plus for serviceability and parts availability -- driving a standard heavy duty alternator -- ditto. This is similar to some home-made DC generators we've seen on here, except that instead of a home-made marinization of an undersized Kubota, this just uses a standard propulsion engine from a much smaller boat.

For a long-distance high latitude adventure cruising boat, I think this is just the ticket -- the ultimate in robustness, serviceability, and simplicity.

I am not a fanboy of DC generators because I don't see any overwhelming advantage in efficiency. Now that we have modern charger/inverters which make a seamless conversion between DC and AC and back, I don't think we really care whether power comes to us in DC or AC form. I like heavy duty low speed AC generators and have had excellent service from my Kohler EFOZ6.5 and would not trade it for a homemade DC generator with a home-marinized Kubota, but something like Noelex's generator is something very different.

I think on my next boat I'll have something like that. I would use a Beta or Nanni, the smallest 3-cylinder propulsion engine they make. I would have a flywheel and jackshaft in place of the gearbox running two large frame Leece-Neville 36 volt or 48 volt alternators through short toothed belts. That will give a capacity of up to 6 or 7kW with both running, but by varying the engine speed and using one rather than both alternators, the output can be regulated.

I would have a third identical 36 or 48 volt alternator on the main engine. This gives great flexibility and redundancy in power generation, and one spares kit will cover all three alternators.

This power will charge a 36v or 48v battery bank, maybe LiFePo, which can absorb high charge rates, using this generator to its best advantage and allowing for short generator runs.

Having this kind of power on board eliminates the question of how to power the windlass, bow thruster, and furling gear.

The DC bank will produce AC power through ganged charger-inverters, maybe three like the Victron Multiplus I have now. This is not an ideally reliable unit, but in a gang of three the built-in redundancy will compensate. Like that there will be about 7.5kW of available AC power.

DC consumers powered through 24v or 12v droppers. Probably there will be one large 24v dropper powering a separate 24v bus.


To make the generator perfectly serviceable, I guess is should live above the main engine and under the cockpit sole. If this is bolted in place and easily removeable, or with a large opening hatch, then access should be ideal.

Everything needed to make the generator run, including its start battery, should be located right there in the same place and should be separated as much as possible from other systems.

Such a generator makes it easy to take off mechanical power for other purposes, but I think there's hardly any point to a mechanically driven watermaker pump or bilge pump, since you have nearly unlimited electrical power for this. Maybe a large mechanical bilge pump would make sense just for the case of some disaster which has knocked out power, but you can still start the generator since its start battery is separate and well above the waterline.

I disagree on the AC in preference to DC for anyone interested in getting off the grid and living cleaner.

For a condomaran running air, massive home fridges and other energy inefficient widgets the need for an always running AC generator is obvious.

We have a kubota DC generator. Its simple, very efficient, quiet and easy to maintain. We have ditched all the AC loads except for the tv and laptops which we now run from small inverters. These days there are so many devices that dont need AC.

We rarely use our 2500W inverter now. Only intermittent loads like a hair dryer, iron, toaster or the odd non cordless power tool.

The plus is that with everything running from DC we dont have the AC to DC inefficiencies which add up significantly. We run a technology startup all on DC and even a TIG from the inverter at no more than 10% duty cycle.

We're now in a position to add some more solar so we can heat hot water. Once we do this we wont need to run our little gennie daily.

Not being dependent on shore power gives us much more freedom to find those great little anchorages that are much more pleasant than having to deal with poorly run marinas.

We cook a lot, daily, use a french press and dont have an icemaker. We've increased our propane capacity which now gives us 6 month of on board energy capacity for all our living needs.

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[Dockhead]

Jo

Originally Posted by leftbrainstuff

I disagree on the AC in preference to DC for anyone interested in getting off the grid and living cleaner.

For a condomaran running air, massive home fridges and other energy inefficient widgets the need for an always running AC generator is obvious.

We have a kubota DC generator. Its simple, very efficient, quiet and easy to maintain. We have ditched all the AC loads except for the tv and laptops which we now run from small inverters. These days there are so many devices that dont need AC.

We rarely use our 2500W inverter now. Only intermittent loads like a hair dryer, iron, toaster or the odd non cordless power tool.

The plus is that with everything running from DC we dont have the AC to DC inefficiencies which add up significantly.

We're now in a position to add some more solar so we can heat hot water. Once we do this we wont need to run our little gennie daily.

Not being dependent on shore power gives us much more freedom to find those great little anchorages that are much more pleasant than having to deal with poorly run marinas.

We cook a lot, daily, use a french press and dont have an icemaker. We've increased our propane capacity which now gives us 6 month of on board energy capacity for all our living needs.

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To each his own. We use lots of AC power on board, and the next boat, with an all electric galley, will use still more. We are hardly "dependent on shore power"; my mooring has no power and I spend plenty of time at anchor. And in ports without usable shore power, since in the Baltic we often end up in commercial ports rather than pleasure boat ports. We don't really care about shore power because we have robust, redundant generating capaciy. AC DC conversion losses are trivial.

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