Triskel power generation system on Distant Shores III

[RaymondR]

Originally Posted by Pete7

What I am slightly confused about is how he is able to get 7kw of power out of what looks like quite a small alternator / generator.

Certainly an interesting option instead on a separate generator. I think there is a bit of marketing hype about saving fuel etc but not having to install a separate generator could be a plus.

Pete

And the belt driving it does not look too hefty also.

[a64pilot]

Originally Posted by Dockhead

It's a very appropriate warning, but something like this can actually be creeping in the opposite direction --


one whole less diesel engine (huge simplification right there)

no proprietary generator set


All you have to do is either keep the alternator size down so that its power requirement doesn't eat up the gap between propeller power curve and maximum output plus a margin.


Or, find a way to modulate the alternator output so you can regulate that issue that way.


I think this is simpler, not more complex, than a separate AC genset.


You do lose the redundancy, but is this something where you really need it? If you've lost the main engine, you've kind of got bigger problems, don't you?


On a catamaran, I would for sure go this way -- having THREE diesel engines on a weight-sensitive unballasted vessel is pure madness.

OK think 48V bank, which has issues of its own, its more efficient of course, but if you lose one battery, it makes it harder to isolate.
Then you have to have a box to down convert to 12V, plus an inverter which you’ll likely have anyway.
The whole loading the engine thing is not insignificant, best done with a variable pitch prop, and you’ll likely need a fly by wire throttle too to vary engine RPM as necessary.

I agree with the Cat thing and cannot in my mind figure out why the bigger cats come with such huge, heavy generators. It would seem they have decided weight is irrelevant or maybe not as important as being able to advertise a 12 KW generator? It may not be 12, but they are bigger than I would think necessary.

Back to all manner of things are possible, electric or hydraulic drive allowing the engine to be placed anywhere and any number of furlers, winches etc to be run, it just takes money and someone not adverse to complexity is all.

[Jammer]

Originally Posted by Dockhead

This idea would work much better if the alternator could be regulated to adjust the alternator output down to not overload the main when it's being used for propulsion, or crank the output way up when the main is being used just for power generation.

This is not technically difficult to do. Balmar and others have a rudimentary form of it -- just a switch with a low and high setting, but with a microprocessor controlled regulator, it's just a matter of software.


It would be feasible, with clever software, to set the limit appropriately based on gearshift position and RPM.

[motion30]

Make no mistake it is not power for nothing, there is no such thing. you certainly will use more fuel and has been stated could possibly overload the main engine. But as long as one understands the limitations it could be a good choice

[Pete7]

Originally Posted by Dockhead

This idea would work much better if the alternator could be regulated to adjust the alternator output down to not overload the main when it's being used for propulsion, or crank the output way up when the main is being used just for power generation..

Isn't this what they are trying to do with a magic box of tricks?

Originally Posted by a64pilot

OK think 48V bank, which has issues of its own, its more efficient of course, but if you lose one battery, it makes it harder to isolate.
Then you have to have a box to down convert to 12V, plus an inverter which you’ll likely have anyway.
The whole loading the engine thing is not insignificant, best done with a variable pitch prop, and you’ll likely need a fly by wire throttle too to vary engine RPM as necessary.

That is a valid point.

I think Dockhead has a feathering prop that varies the pitch depending on input power. Not cheap but could be interesting.

Wonder what the price will be, those batteries alone are £424 each in the UK. Suddenly a Honda 20i looks attractive on a small boat.

Pete

[MaCro]

The website for this product is now live at https://www.integrelmarine.com/

Looks like it does use a 48VDC 170A Alternator, externally rectified in the controller/regulator/charger. Comes with a 3KW inverter/charger, additional optional.

Works with any battery chemistry - looks like it can be the BMS including low-voltage disconnect for LiFePo4.

[a64pilot]

He and I both have an Brunton’s Autoprop, which I believe was originally designed as a way of getting a WWII landing craft off of a beach, cause the blades flip around and the leading edge of the prop is still the leading edge in forward or reverse, so it’s just as effective and efficient in either direction.

However the Autoprop self pitches based on a balance of centripetal force and induced flow, centripetal force flattens the pitch, while indices flow increases it.
What this does is makes the load on the engine the same for a given RPM, regardless of speed, which makes it very good for motorsailing. It’s brilliant for that. It functions like an automatic transmission in effect.
However it won’t compensate for loads placed on the engine from an external source, like pulling power from the crankshaft.
That would I believe take a controllable pitch prop and an exhaust pyrometer as exhaust temp is a good indicator of load on a Diesel.
You would use manifold pressure for a spark ignition engine.

[stormalong]

Originally Posted by Dockhead

As some one who absolutely cannot fit solar anywhere, I have to disagree with this. There are absolutely many use cases where a significant amount of solar power is not possible.

And solar is the only "alternative power source" which is capable of generating significant amounts of power for a large cruising boat with lots of electrical gear on board. Wind and "drag prop" (I assume you mean a towed generator?) are very minor producers.

The boat in the video could fit a lot of solar on his stern if he fit a Bimini.

Drag prop generators have matured from the Four Winds and Hamilton Ferris generation. Have you heard of Duogen? There is also A French product that I can't think of the name of right now that is very cool but is about seven grand. It does produce a lot of power.

Wind powered generators can be good for windy areas also.

I sailed many trade wind ocean passages with an electric autopilot and got 100% of my power from a combination of solar and wind & water powered generators.

Granted I did not use electric toasters or air conditioning but all of my needs were met.

Total dependence on engine driven electric power is foolhardy if you are cruising the world.

[stormalong]

Here is a link to a Sail Magazine article on hydro powered generators.


https://www.sailmagazine.com/diy/kno...222215-9519440

[Q Xopa]

Originally Posted by Dockhead

The advantage is that you can do a lot of charging when you're running the main engine anyway. Besides that, you don't have to buy and maintain and amortize a whole nother diesel engine. Those are pretty big advantages.

Yes very interesting.

The 'control' system they were using looked interesting. If it can wind back the generator requirements as the engine needs more it sounds like a good concept.

7kW is heading in the right direction but for a 75Hp engine at anchor its only a fraction of ideal. I would suggest something like 55 HP, which is around 40kW is a more efficient load range.

Also that Serpentine belt set up for a 7kW drive. Lets see but my guess is its ambitious. 7kW has to be way north of 10HP.

No its not 'something for nothing'. Its also certainlty more fuel. However it may well be a little bit more diesel for a proprtionaly lot more power. If the engine load can be maximised in the high SBFC range its a step in the right direction. Typically it will take in the order of twice the amount of diesel per HP produced at idle than at max TQ RPM.

This would be far more efficient with a larger gen, 40kW and a large LFP, high charge effiency to suck up all of the Amps, set up.

Anyway just to completely set the cat amongst the pigeons.

This is basically a parallel hybrid setup.

As has been mentioned redundancy is reduced. But overall reliability has increased as there is less engines with bits to break down. Its the old 2 or 4 engine aircraft discussion.

[tanglewood]

I think it's quite common for people to think that power generated from the main engine is "free" compared to running a generator. But in terms of fuel consumption, it certainly isn't. Your main will burn more fuel when generating 7kw vs when not, just as your generator will. Which will be more is a complex formula based on relative loading of the two motors and their respective bsfc, plus the efficiency of the electrics to generate and get the power into a usable form.


About a year ago I conducted an experiment on our boat to compare fuel burn vs power generated, looking at the main engine/alternator and the generator as power sources. For light loads (light is a relative term), the main/alternator was better. At that load, power losses in the alternator were low making it better, and efficiency in the generator engine were poor handicapping it. But for heavy loads, the generator was better. It's engine was operating at an efficient load, vs the large power losses in the alternator at high loads.



Adventures of Tanglewood: Engine Alternator or Generator: Which is More Efficient?



Now fuel consumption is only once consideration. If using your main engine lets you get rid of a generator all together, I can see that being compelling. I know other people who just want to reduce the maintenance interval on their generator, so prefer to use the main+alt.


As always, there is no "right" answer. But there can be lots of misunderstanding that will lead to bad conclusions.

[Q Xopa]

Originally Posted by tanglewood

I think it's quite common for people to think that power generated from the main engine is "free" compared to running a generator. But in terms of fuel consumption, it certainly isn't. Your main will burn more fuel when generating 7kw vs when not, just as your generator will. Which will be more is a complex formula based on relative loading of the two motors and their respective bsfc, plus the efficiency of the electrics to generate and get the power into a usable form.


About a year ago I conducted an experiment on our boat to compare fuel burn vs power generated, looking at the main engine/alternator and the generator as power sources. For light loads (light is a relative term), the main/alternator was better. At that load, power losses in the alternator were low making it better, and efficiency in the generator engine were poor handicapping it. But for heavy loads, the generator was better. It's engine was operating at an efficient load, vs the large power losses in the alternator at high loads.



Adventures of Tanglewood: Engine Alternator or Generator: Which is More Efficient?



Now fuel consumption is only once consideration. If using your main engine lets you get rid of a generator all together, I can see that being compelling. I know other people who just want to reduce the maintenance interval on their generator, so prefer to use the main+alt.


As always, there is no "right" answer. But there can be lots of misunderstanding that will lead to bad conclusions.

Im not sure I understand the logic of trying to save on generator maintenance run time?

That would tend to increase main engine run time wouldnt it?

Isnt servicing 2 engines less frequently more or less the same as servicing one twice as frequently? Its a similar number of oil filters etc, which are pretty similar costs over a given period.

If its to delay having to replace a gen set. Arent they mostly cheaper than main propulsion engines.

Im a little suprised you find its more economical to run your main for light loads. You put it down to your alts seem more efficient at lighter loads?

Good work uncovering some of these details.

[tanglewood]

Originally Posted by Q Xopa

Im not sure I understand the logic of trying to save on generator maintenance run time?

That would tend to increase main engine run time wouldnt it?

Isnt servicing 2 engines less frequently more or less the same as servicing one twice as frequently? Its a similar number of oil filters etc, which are pretty similar costs over a given period.

If its to delay having to replace a gen set. Arent they mostly cheaper than main propulsion engines.

Im a little suprised you find its more economical to run your main for light loads. You put it down to your alts seem more efficient at lighter loads?

Good work uncovering some of these details.

It all depends on the situation. I would never suggest running a main engine in place of a generator ONLY to generate power, and I think you are saying the same thing. I'm referring to using the main to generate power while also using it for propulsion. We happen to be a power boat, so the main is always running when we are underway.


A good example might be doing laundry while underway since that can draw a lot of power. I know people who, rather than run their generator,
prefer large alternator(s) and inverters. This would save run time on the generator, but would not save fuel, and might actually burn more.

[a64pilot]

Power boat would be a whole different use case.
We often default here to thinking about sailboats.

However I’d say fuel consumption is basically irrelevant, unless running an engine for air conditioning etc. as that is many hours.

Fuel burn for power produced is astonishingly flat, unless we are talking about running a 671 to power our fridge compressor or something ridiculous.
The sweet spot on a Diesels BSFC isn’t all that much more fuel efficient per work done, the major difference between a larger engine and a smaller one in fuel per HP produced, assuming HP is the same is the difference in friction of the bigger engine over the smaller one. Again within realistic examples, yes the monster ship Diesels are much more efficient, but the difference between a generator three cyl Diesel and the primer mover four cylinder just isn’t much.

The logical end of systems like this is a pure Diesel electric hybrid, where your Diesel makes electricity and it’s distributed however necessary to storage or to run any number of different things, including propulsion.

There is a reason you don’t see that on boats of our size

[nwdiver]

Narrowboats use travel power systems all the time, they are very common I don't get reinventing the thing, this is nothing new........a friend does laundry, charges his batteries and makes ice everytime he toodles along a canal........but they run their engines regularly....sailboats, ideally not so much.....