Ideal Generator?

[Dockhead]

Originally Posted by valhalla360

Again, I'm not saying electricty should be shunned and feared. Most of the issues can be traced back to someone doing something stupid (just like most propane fires). Stupid people amazingly inventive, they will find a way.

I can see some advantage to eliminating a system to keep things simpler but if you are requiring multiple generators...simplicity goes out the window. I think I've lost track of why you are intent on an all electric boat. What was the reason?

Electricity, fire, propane -- all risks on a boat which have to be managed. Electricity very rarely causes a problem without badly installed wiring or something really stupid. One reason why I hate propane, although it is probably not more dangerous than fire, is that many accidents occur without stupidity being involved -- why I posted the Royal Navy incident.

Yes -- eliminating the entire system simplifies and improves managing these safety issues.

Electric cooking does NOT require multiple generators. It would be a challenge on really lean low powered solar boats, but on boats designed to support a lot of AC power consumption, it's no problem. I already cook with an electric oven (countertop; because my gas oven is such crap), a microwave/grill (by far the most used appliance), electric kettle for boiling water for tea etc., electric Nespresso coffee machine, and an electric induction stove (countertop, when I'm out of gas). My present boat has far less battery and generating capacity than the next one will, yet electric cooking is just no problem whatsoever. Dinner, with more elaborate cooking going on, usually done while a generator run is going on, but lunch from the inverter with no problem, plus coffee and tea throughout the day.


The whole thing is a question of system architecture -- how to design the systems on your boat so they are as robust and failsafe and repairable as possible. Rather than using many different power sources, it is better to use a single one if possible, and concentrate resources on making that one system as robust as possible. That's the main idea here, with safety as an important side benefit.


One really good thing about gas, however, is that other than running out of it, there is no problem with it which you can't repair with simple tools and a few cheap spares. This of course is a big advantage which I will miss. But my new boat will have a very carefully designed electrical system which should be nearly failsafe. And running out of gas is also a problem in remote places. Diesel fuel is much easier to get.

I'm very happy with the electrical system on my present boat. It's the only system, probably, which has never given me any trouble, other than a failed charger/inverter. Electric cooking is not ideal for the grand gourmet chef, but on a boat with reasonable power capacity, it has a long list of advantages. Not the least of which is not putting water vapor and combustion products into the closed atmosphere of a boat cabin, especially one which is closed up in cold weather.


Edit:

I found this on Dashew's site:

"Matt Marsh Says:
June 11th, 2010 at 8:25 am
I seem to recall you posted some material about this oven’s electric consumption last year (about 20-25 Ah at 24V, IIRC, for 40-50 minutes of baking). Now that it’s in regular use, can you comment on how much load it’s really putting on the batteries over longer periods- especially since convection ovens, supposedly, bring a considerable reduction in baking time? From what I’ve seen among Web retailers, the pricing for this unit plus a couple of simple induction range elements appears to compare favourably with some of what passes for “marine grade” cooking equipment…. if the added load on the batteries isn’t too huge, I think such a setup would be vastly preferable to propane.
Steve Dashew Reply:
June 11th, 2010 at 9:37 am

Hi Matt: We do not have an easy way to isolate the cooking loads. However, in the next month we will conduct some meal prep experiments with everything else turned off, in which case we can use our amp hour meter. Basically, we have seen not measurable difference in generator run time with this cooking system as compared to using propane."

http://www.setsail.com/panasonic-ove...es-to-impress/


That goes to the question of whether electric cooking only makes sense on superyachts with dual generators.

My own experience has been the same. On my present boat, where we have a lot of AC equipment and the inverter is running 24/7 anyway, cooking on an induction hot plate and with an electric oven, not to mention the kettle, microwave, etc., etc. -- just doesn't make any noticeable difference, since we are generating power for all kinds of other purposes anyway.

When my batteries were still fresh, I could get away with a single generator run a day, usually 2 to 3 hours. I would do that during dinner preparation, and would time other heavy loads to coincide (washer/dryer etc.).

Having a really good generator which is quiet and has a pleasant tone is, of course, really important in this whole picture.

[darylat8750]

Originally Posted by a64pilot

Jackshaft is indeed easy, two U joints and two pillow block bearings. I believe you do not want it straight either, but I don't have a reference.
Trick obviously is having a transmission with a PTO

Yep the farm equipment is inexpensive and readily available. The common ones are designed to operate at 540 rpm or 1000 rpm. And farm equipment usually does not have vibration dampers. I would have some concern about torsional vibrations so at least one of the u joints (or variation thereof) should include a vibration damper of some sort. I don't think you would need the pillow block bearings. The crankshaft on the front of either the main engine or the genset has good bearings. And the alternators are designed to be driven by belts and shaft drive would be much easier on the bearings.

[a64pilot]

Well I didn't mean Farm equipment, but nothing wrong with that I guess. I'd go more along the lines of a constant velocity driveshaft from a small car type of thing, they last for a very long time, and turn quite high RPM I believe.
I believe a common PTO would put a jack shaft parallel to the main drive shaft, ought to be room to do that, and have it accessible.


Sent from my iPad Pro using Cruisers Sailing Forum

[Dockhead]

Originally Posted by a64pilot

Well I didn't mean Farm equipment, but nothing wrong with that I guess. I'd go more along the lines of a constant velocity driveshaft from a small car type of thing, they last for a very long time, and turn quite high RPM I believe.
I believe a common PTO would put a jack shaft parallel to the main drive shaft, ought to be room to do that, and have it accessible.

If the generator engine is not used for propulsion of any kind, I will just run the jackshaft straight off the flywheel, I think. It won't be longer than main engine plus marine gear so I'm imagining this side by side with the main engine, or above it (like my present generator), or on a shelf above the main engine and off to one side.

A cut-off length from a small shaft from a small yacht is what I had in mind for the jackshaft, connected via CV joint or flex joint, and supported by a couple of robust pillow blocks, was what I had in mind, but I'll let a real engineer design and specify it. Maybe ready-made farm equipment would be a good approach.

I guess the alternators would be driven with belts off pulleys on the jackshaft.

Possibly there is a simpler way to do it if off the back of the engine rather than the front.

[Dockhead]

Very interesting to study how Dashew does all this on his boats. This is a power boat, of course:

Northwest Passage 2014: A Unique Opportunity - PFB-64 M/V IRON LADY for sale asking US$ 3,100,000 - AFFORDABILITY ALTERNATIVE BELOW?

So not quite the same challenges, but still very interesting.

He has an electro-centric approach with 24v electric windlass and thruster -- no hydraulics. AC power is used for almost everything else including fully equipped galley, watermaker, etc.

He has a very large lead-acid battery bank (over 1000 a/h's at 24v) charged by an 11kW Onan low speed generator.

He can duplicate the generating ability of the Onan generator with two very large alternators drive off the single main engine using serpentine belts.

AC to DC to AC conversions are done by a gang of Victron charger-inverters just like I have been thinking. I note that he has a bypass switch for the inverters -- maybe he's experienced some of the problems I have!

Note that he has a backup propulsion engine (100hp Yanmar) with a folding prop. More important for a power boat than for a sailing one (although the FPB has emergency sails).

Photos of the engine room are pure boat porn:

SetSail » Blog Archive » FPB 64-6 Grey Wolf: Engine Room Art

[darylat8750]

Originally Posted by Dockhead

If the generator engine is not used for propulsion of any kind, I will just run the jackshaft straight off the flywheel, I think. It won't be longer than main engine plus marine gear so I'm imagining this side by side with the main engine, or above it (like my present generator), or on a shelf above the main engine and off to one side.

A cut-off length from a small shaft from a small yacht is what I had in mind for the jackshaft, connected via CV joint or flex joint, and supported by a couple of robust pillow blocks, was what I had in mind, but I'll let a real engineer design and specify it. Maybe ready-made farm equipment would be a good approach.

I guess the alternators would be driven with belts off pulleys on the jackshaft.

Possibly there is a simpler way to do it if off the back of the engine rather than the front.

The Northern Lights gensets have a clutched power take off on the opposite end of the engine from the generator head. If you used a low rpm generator you could direct drive from that without the complication of a jack shaft, bearings belts ect. That would be a very simple and robust solution. If the a/c generator head quit for some glitch in the control system you would still have a big alternator powered by the genset engine in addition to the main engine. As you are designing from scratch you may be able to drive another of the same alternators off the front of the crankshaft of the main engine without affecting the factory installed engine mounted alternator. And/or....you could replace the factory alt. with another of the big alternators on the engine to be belt driven. That could give you 3 heavy duty dc alternators mounted and in use with the flip of a switch. Plus your Northern Lights genset. You would need failure of both diesel engines to run out of generating capability.

The only disadvantage that I see of doing it this way is the extended length of the genset and main engine. With a jack shaft you can put the bulk on the sides of the engines instead of inline at the expense of complication.

[a64pilot]

I was envisioning the PTO off of the main engine so that you could drive huge alternators if the gen quit.
I still think you are better served with a production quality generator as primary power. They have evolved over the years to current level of reliability, no science experiment there.


Sent from my iPhone using Cruisers Sailing Forum

[Panope]

Dockhead, The more I read about your boating style and power generation goals, the more I think that a twin engine boat (with no other I/C engine) might be best for you.

-Two identical engines mounted in the typical side by side fashion.

-Each engine has enough alternator(s) to meet your "normal" electricity/charging needs. If you need "super power", just start the other engine.

-Each engine will be 1/2 the horse power of a single engine installation and therefore will be better sized for use an electric plant (at anchor).

-Normal, no-wind motoring will be done on one (appropriately sized) engine. Again, when the need to buck your Baltic F8 arises, just start the other engine.

-Twin rudders means you get redundant steering and autopilot (if two of those are installed).

-Twin engines reduce or eliminate the need for a bow thruster.

I only see one drawback among vast improvements in every other area: Sailing drag of two propeller running gears will be more than a single engine installation. The fact that these running gears will be half the size of an equal trust single installation will mitigate the added drag of twins somewhat.

Naturally, what is described above is what virtually all catamarans have. No reason not to have the same set-up in a Mono.

Steve

[pdf27]

Originally Posted by Dockhead

Absolutely fascinating and totally cool. Thanks very much for that. That could be revolutionary. Query how long it will take to develop, however.

Had a little free time this afternoon and managed to get my head around the maths. Unfortunately it doesn't work out the way I was hoping it would with regards to matching propeller and engine together - unfortunately the fixed torque ratio means that if you're gearing up to let the engine run at artificially low revs then you need to inject electrical power into the gearbox in order to keep everything working. To extract power you need to have the engine turning over faster than you otherwise would have done. For a sample engine (Yanmar 4JH3-DTE) you're looking at an additional 1-200 RPM to generate 2kW of additional power.
There are still some clear benefits to such a system (with the engine stopped, for instance, you can use it in parallel hybrid mode, and it seems to be quite a smooth and efficient reduction gearbox), but it unfortunately doesn't do what I was hoping it could thanks to the fixed torque ratio and variable gear ratio.

Incidentally exactly the same maths applies to the Prius power split system if you applied that to turning a propeller - if you want to extract energy from it the engine has to be turning over faster than it otherwise would.

[darylat8750]

Originally Posted by Dockhead

Very interesting to study how Dashew does all this on his boats. This is a power boat, of course:

Northwest Passage 2014: A Unique Opportunity - PFB-64 M/V IRON LADY for sale asking US$ 3,100,000 - AFFORDABILITY ALTERNATIVE BELOW?

So not quite the same challenges, but still very interesting.

He has an electro-centric approach with 24v electric windlass and thruster -- no hydraulics. AC power is used for almost everything else including fully equipped galley, watermaker, etc.

He has a very large lead-acid battery bank (over 1000 a/h's at 24v) charged by an 11kW Onan low speed generator.

He can duplicate the generating ability of the Onan generator with two very large alternators drive off the single main engine using serpentine belts.

AC to DC to AC conversions are done by a gang of Victron charger-inverters just like I have been thinking. I note that he has a bypass switch for the inverters -- maybe he's experienced some of the problems I have!

Note that he has a backup propulsion engine (100hp Yanmar) with a folding prop. More important for a power boat than for a sailing one (although the FPB has emergency sails).

Photos of the engine room are pure boat porn:

SetSail » Blog Archive » FPB 64-6 Grey Wolf: Engine Room Art

Serious boat porn! I've followed Steve and Linda since the '80s. If I had the money I would own one of Dashews boats. I believe they do have hydraulics for the stabilizers.

[Dockhead]

Originally Posted by Panope

Dockhead, The more I read about your boating style and power generation goals, the more I think that a twin engine boat (with no other I/C engine) might be best for you.

-Two identical engines mounted in the typical side by side fashion.

-Each engine has enough alternator(s) to meet your "normal" electricity/charging needs. If you need "super power", just start the other engine.

-Each engine will be 1/2 the horse power of a single engine installation and therefore will be better sized for use an electric plant (at anchor).

-Normal, no-wind motoring will be done on one (appropriately sized) engine. Again, when the need to buck your Baltic F8 arises, just start the other engine.

-Twin rudders means you get redundant steering and autopilot (if two of those are installed).

-Twin engines reduce or eliminate the need for a bow thruster.

I only see one drawback among vast improvements in every other area: Sailing drag of two propeller running gears will be more than a single engine installation. The fact that these running gears will be half the size of an equal trust single installation will mitigate the added drag of twins somewhat.

Naturally, what is described above is what virtually all catamarans have. No reason not to have the same set-up in a Mono.

Steve

The thought has occurred to me, and it is discussed in one of my posts above.

[Dockhead]

Originally Posted by a64pilot

I was envisioning the PTO off of the main engine so that you could drive huge alternators if the gen quit.
I still think you are better served with a production quality generator as primary power. They have evolved over the years to current level of reliability, no science experiment there.


Sent from my iPhone using Cruisers Sailing Forum

No, I don't need a PTO off the main. Yanmar deliver some of their engines, like my present 4JH3 and also the 6 cylinder one I"m looking at for the new boat, with the school bus alternator already installed. That's 2.5kW which is quite decent backup generation power.

The PTO would be for the auxiliary engine, to drive two school bus alternators for prime generation.

Yes, a Northern Lights AC generator similar to my present Kohler is the other way to do it, with certain advantages. I have been very happy with my heavy duty, continuous duty rated, low speed Kohler.

But the advantages of doing it with school bus alternators I have described in posts above, and are pretty compelling, for cruising in remote areas.

[mcarling]

If I had to have a diesel-fueled generator, I would choose a gas turbine. Bladonjets make one 12KW. Capstone make them in 30KW and 65KW. Then I would use an electric motor for propulsion. Silent in and out of marinas, possibly consuming electricity from the solar panels. Long distance motoring would requiring running a gas turbine, without the vibration of a reciprocating engine. No worries about bad fuel, virtually zero maintenance, eliminates a through-hull, and much more reliable than reciprocating engines. Routing the exhaust might be a challenge, but there is freedom of where to locate the gas turbine.

[Dockhead]

Originally Posted by mcarling

If I had to have a diesel-fueled generator, I would choose a gas turbine. Bladonjets make one 12KW. Capstone make them in 30KW and 65KW. Then I would use an electric motor for propulsion. Silent in and out of marinas, possibly consuming electricity from the solar panels. Long distance motoring would requiring running a gas turbine, without the vibration of a reciprocating engine. No worries about bad fuel, virtually zero maintenance, eliminates a through-hull, and much more reliable than reciprocating engines. Routing the exhaust might be a challenge, but there is freedom of where to locate the gas turbine.

Sounds very intriguing, and I think someone suggested that in this thread above. I would love to see something like this developed.

But certainly out of the question for a vessel such as the one I'm working on specifying. For this particular vessel, which is supposed to be extremely reliable and field serviceable, the design can't have anything exotic in it. Imagine trying to get a turbine mechanic in Greenland, or jet fuel in one of the fishing ports up there, and imagine how much one-off engineering such a system would take.

I need something extremely simple and conservative. The inherent reliability of reciprocating engines is not one of the design problems.

[mcarling]

Gas turbines run fine on diesel (or just about any liquid or gaseous fuel). MTBF is typically over 100,000 hours. In the size range we're talking about, they have air bearings, so there is literally only one moving part. In the extremely unlikely event of failure, there is nothing at all a turbine mechanic can do with a small turbine but replace it. A much more likely (but still unlikely) failure would be with the attached generator.