Ideal Generator?

[stefano_ita]

http://www.mme-generators.com/sites/...ril_2014_2.pdf


5 liters hours ( about 1,3 galoon) for 10 kw outpout...

However i really like the idea...and the exhaust direct to the stern for more propulsion

[brianlara 3]

SETTLE DOWN STEPH'

[stefano_ita]

Originally Posted by brianlara 3

SETTLE DOWN STEPH'

Mh..

Ok the exhaust directed on the mainsail, for FRESH breeze

AAA offers for best offers a new mainsail, like new, melted dacron style, few miles, always store in lazy back against UV ray

[brianlara 3]

Originally Posted by stefano_ita

Mh..

Ok the exhaust directed on the mainsail, for FRESH breeze

AAA offers for best offers a new mainsail, like new, melted dacron style, few miles, always store in lazy back against UV ray

Buy your mushrooms from the super market Stephano.
I think you will find they have fewer side effects than the mushrooms you are collecting in the field.

[stefano_ita]

Originally Posted by brianlara 3

Buy your mushrooms from the super market Stephano.
I think you will find they have fewer side effects than the mushrooms you are collecting in the field.

Lol...This forum lacks of humor, especially italian humor

End off topic

[brianlara 3]

Stephano, my humour with you was tanti posto for a long time.

[mcarling]

In my opinion, the best generator is usually a solar array.

[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.


Sent from my iPhone using Cruisers Sailing Forum

[stefano_ita]

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.


Sent from my iPhone using Cruisers Sailing Forum

QUOTE 100%

[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.


Sent from my iPhone using Cruisers Sailing Forum

The high output alternator(s) don't require diesel? Please provide the model numbers!

[mcarling]

Originally Posted by DotDun

The high output alternator(s) don't require diesel? Please provide the model numbers!

Please read again what Agility wrote.

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

[valhalla360]

Originally Posted by a64pilot

I have never seen hydraulic drive on a yacht, but many ferries etc., but then how many Yachts have I seen, not many.
Hydraulic is about as KISS as it gets, very simple system and I'd want it for redundancy of two power plants, and the more customers you have, the more sense it makes, hydraulic thrusters and furlers I think are mainstream.
One of it's advantages is you can now put the engine(s) anywhere you want to, even get real slick and have a retractable drive, anything is possible if you have enough money.

Same for electric I guess, I'm just more comfortable with hydraulics in salt water.

I don't think you can replace an AC generator with alternators, not really. Forgetting conversion losses just to power a 30 amp boat, you need 300 amps of 12 VDC, half that for 24 of course.
I haven't yet seen an alternator make full, rated output, especially not continuously.
I suspect the real, continuous output of an average alternator is about half, maybe three quarters of its rated power at best.
With a huge battery bank, and massive charging capability, I guess you could replace a generator.

I think some early catamrans used a single engine providing hydraulic to two props. I've not seen any recent boats with it though.

I would probably go for diesel/electirc over hydraulic. Not the most efficent system but much more flexible. You could size one generator for house loads and light duty propulsion (getting in and out of a slip or just tooling along at slow speed). Then have a seond generator that could be cranked up and combined to provide continous full power to the electric motors. Either diesel generator fails or either electric motor fails and you still have propulsion, so good redundancy.

Ideally, it would be two identical generators so you switch back and forth and keep both exercised. Also, spares work for either engine. But if you need say a 10hp generator for house loads but two 20hp generators for max propulsion, a pair of 10hp generators is underpowered for propulsion and a pair of 20hp generators is overpowered for house loads, so a 10hp and 30hp generator pair might make more sense.

Then again look at the efficency or running a 20hp generator at 10hp output. Assuming that it's a modern unit that can adjust the throttle to load, the 20hp generator may not use significantly more fuel.

While I think it will still come out a little more expensive, if you are building a boat from scratch, it might not be that much more as you are trading off a dedicated house diesel/generator and two transmissions for a pair of electric motors and the generators to mount on the back of the diesel propulsion engines. It's just a question of if you feel the redundancy and flexibility are worth the extra cost plus probably a small loss in efficency.

Agree about the alternators. They are Ok for topping up the batteries occasionally when the solar isn't keeping up but for dedicated heavy duty use, a purpose built generator makes more sense.

[Dockhead]

Originally Posted by valhalla360

. . .
Agree about the alternators. They are Ok for topping up the batteries occasionally when the solar isn't keeping up but for dedicated heavy duty use, a purpose built generator makes more sense.

If I didn't answer this before -- it is important to note that there are alternators, and then there are alternators.

Car-type alternators which are standard fit on marine diesels are not made for bulk power production. They cannot put out their rated output for long, and are not made for high temperature operation. You will burn them up if you try to get maximum output out of them on a continuous basis. That's because a car's alternator has an easy life -- replaces a very small amount of charge lost during starting, and runs on-board loads. There are no deep-discharge battery banks on cars. So they are designed and built accordingly, and not for the way we use them.


School bus type alternators are totally different. These massive beasts are designed and intended to produce bulk power, and are rated to do it in high ambient temperatures, 100C and more. These weigh up to 30 or 40 pounds and are massively built. They will produce their full rated output 24/7/365 even in 200 degrees F conditions.

These devices are especially good for cruising because they are simple, relatively cheap, and easy to repair using cheap and highly standardized parts. You can carry an entire complete spare one without too much trouble, or don't even bother because any third world auto electric shop can fix it, or carry the few spares involved and fix it yourself.

As someone above noted, you have to be careful not to exceed the specs for front power takeoff, if you're driving one of these from the front pulley of a main engine. For my engine, that's about 5 horsepower, so a bit of margin of error over the 2.5kW output of my secondary alternator. I reckon if you were designing such an installation from scratch, you could mount two of them -- one on either side of the main engine -- in order to even out the loads and eliminate the side loading issue.


A couple of people in this thread were arguing for normal, heavy duty AC generators -- that's also a pretty good solution IMHO. If it breaks, it's a lot harder to repair than a school bus alternator, but in my experience, these are very reliable.

It helps if you're using 230v AC power, because the 230v 50hz versions of these generators are de-rated by about 20%, so both the engine and the generator head are producing only 80% of the power they were designed for. One great help for reliability is also using a charger/inverter with power boost, which allows you to strictly limit the amount of power you take from the generator, preventing it from ever being overloaded. I leave mine set on 25 amps, so de-rated AGAIN. I am hoping that the generator head will last more or less forever, used like that.

A few people have come on here advocating solar, although that was not the question. Solar is the IDEAL power source, but only IF you can afford the windage and find space to mount enough solar to meet your power budget, AND if you're using lead acid batteries. Neither of these will be true on my next boat. My next boat will be very low windage for good upwind performance, with dinghy kept below deck etc. I also expect I will be using LiFePo batteries, which work really well with large generator capacity. So I will concentrate on mechanical generation as the main power source.

With LiFePo batteries, you might not even need to run the generator much, because you can get a full charge incidental to even short motoring, if you have big enough alternators on the main engine. In fact, the generator becomes less and less important, because charging with the main engine becomes much more efficient. If you're taking 5kW off your main engine from large dual alternators, this is already a decent load on the engine, and you won't need to run it for long -- a far cry from running the main engine for hours with a small alternator trying to charge up lead acid batteries.

By the very same principle, charging with a heavy duty AC generator also becomes much more efficient, with LiFePo batteries, due to the shorter generator runs.

[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.

[valhalla360]

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

A 300amp alternator is eqiuvilent to less than 5hp. Assuming a boat of similar size to your current boat, I would think 10hp at the prop would be needed for marginal limp along speed and more realistically, I would want at least 20hp as backup for a 50' boat. That would be bolting 4 300amp alternators to the front of the engine. A dedicated generator connected to the crank shaft makes much more sense in my mind once you get much more than a single 300amp alternator.

If you are going to skip the backup propulsion and go with more modest house demands, a single 300amp alternator becomes a more reasonable option.