Triskel power generation system on Distant Shores III

[a64pilot]

Originally Posted by Dockhead

With a fixed prop it doesn't matter.

You know I hate to keep arguing, but it does matter, but it’s not a huge difference, you have had your Autoprop too long and have forgotten
You can demonstrate the difference by running your boat at full throttle tied to a dock and then do so just underway, you’ll usually see I believe about a couple hundred RPM difference.

The fact that it does matter is where and why the Autoprop works, it can adjust pitch to maintain a constant thrust, the effect of slamming into wind and waves is just the opposite of motor sailing of course.
An Autoprop equipped boat will slow more than a fixed prop boat when slamming to weather, it’s because the Autoprop will decrease pitch to keep engine load about the same.

On edit, back to that pyrometer, if you had one you would see that it matters, just the governor will add fuel to try to maintain RPM when headed into wind and waves so the tach shows little difference, the governor masks the increased work the engine is doing. A pyrometer would highlight it.

[rom]

Originally Posted by Dockhead

With a fixed prop it doesn't matter.

Can you elaborate a little bit because I don't see how wind on the nose or big alternator make any difference from the engine POV.

[Q Xopa]

Originally Posted by a64pilot

Depending on engine size and how your propped, there isn’t as much space between those curves as you may think, and it will differ from boat to boat due to exhaust restriction.
However I believe from just talking to a few the average cruiser that has been out a while and has re-propped their boat tends to over prop a bit, and cruise lower RPM, burn a little less fuel but the noise and vibration is much lower. But that gap gets even smaller if they do, a little over propping as long as your not that guy that believes you need to run the snot out of a Diesel to make one last is fine. If you over prop you give up that last third of the throttle except for an emergency.
However my point is or was that you can fill that gap if you want to with one or two large alternators, but you should monitor for overloading if you do, you don’t blow black smoke until seriously overloaded so that’s not a good way. A Pyrometer is probably the easiest and cheapest way, but those numbers will vary according to where it’s mounted.
On my truck I didn’t want to continuously Cruise above 900 to 1000 and I had it set so that at 1400 it would de fuel to stock levels at 1400, the alloy pistons are made from melt at 1400, but the piston is never as hot as the exhaust gas, but I figured that was pushing it as hard as I wanted to, it was a “hopped up” motor as you can probably guess.

I think stock trim it would pull as a max about 1000 EGT, and 23 lbs of boost, I turned the boost up to 32 lbs.

So to determine your cruise temp I’d run it hard without much alternator load, find the hottest it got and back off a couple of hundred degrees, and use that as your max for cruise. I like a thick layer of fudge.

Interestingly on my truck they way it would get real high EGT was pulling a hill but not downshifting, to lower the EGT push the pedal down and force a downshift and temp would drop drastically.
It was of course overloaded until it downshifted.

As you say EGT numbers will vary depending the specific engine and instalation position of the thermocouple probe.

But as you say determining your max temp running the motor BTTW and noting the stable idle temp for the min. This gives you your EGT range. Then you can determine your desired cruise range. 200F off the top/ 75 or 66% your range, or whatever you feel comfortable with.

As you also correctly say the more load over longer periods will shorten its ultimate life.

But I also agree with Dockheads comment saying maintenance time, and operating costs, can be saved by consolodating multi tasks.

I also agree with both of you that a double high output alternator installation is a good cost effective way to achieve this.

This is the way I have gone with 2 x 110A, 24V 'school bus', large case alts. These are around $350 new, so I bought an extra one for a spare.

This is 5kW of power that I have cobbled together for a small fraction of the prices being bandied around.

Its not an off the shelf solution, so not for everyone, as I have played around with mounts, pulleys, alignment but its not that hard, and certainly a lot less than other off the shelf solutions.

[a64pilot]

I’m not disagreeing with big alternators, I have one, or a biggish one, to go large frame would be way more work than I’m willing to put it into it as the stock location almost touches the engine surround as it is.

I understand the attraction of a turn key system too, it’s why I went with a Balmar reg and serpentine kit.

It’s just that in my opinion that $20K is steep for what you could do with a couple of big alternators, and is not in my opinion a replacement for a generator unless we are talking Honda generator.
I base that on the 10 KW battery bank. A 10KW bank only replaces an hour or two of generator run time.

No, I think the Leece Neville alternator makes even more sense than a military alternator based on availability of spares and overhauls, which is another point here, how available and how expensive are parts for this system?

But if you are a big power user and Solar won’t do it or isn’t an option for whatever reason, then unless you expect to motor almost every day, using the propulsion motor isn’t in my opinion a replacement for a generator.

Simply put a generator is designed and manufactured to make power, your propulsion engine is designed and manufactured to propel the boat, yes either can be made to do the others job, but it’s a less than optimum solution.

Using the propulsion engine as a generator makes a whole lot more sense in a trawler or other power boat in my opinion because of course anytime it’s moving, the engine is running, but it makes less sense for a sailboat, plus due to engine size a power boat has a lot more available power to tap than many smaller sailboat engines.

[Q Xopa]

Originally Posted by a64pilot

I’m not disagreeing with big alternators, I have one, or a biggish one, to go large frame would be way more work than I’m willing to put it into it as the stock location almost touches the engine surround as it is.

I understand the attraction of a turn key system too, it’s why I went with a Balmar reg and serpentine kit.

It’s just that in my opinion that $20K is steep for what you could do with a couple of big alternators, and is not in my opinion a replacement for a generator unless we are talking Honda generator.
I base that on the 10 KW battery bank. A 10KW bank only replaces an hour or two of generator run time.

No, I think the Leece Neville alternator makes even more sense than a military alternator based on availability of spares and overhauls, which is another point here, how available and how expensive are parts for this system?

But if you are a big power user and Solar won’t do it or isn’t an option for whatever reason, then unless you expect to motor almost every day, using the propulsion motor isn’t in my opinion a replacement for a generator.

Simply put a generator is designed and manufactured to make power, your propulsion engine is designed and manufactured to propel the boat, yes either can be mode or do the others job, but it’s a less than optimum solution.

Using the propulsion engine as a generator makes a whole lot more sense in a trawler or other power boat in my opinion because of course anytime it’s moving, the engine is running, but it makes less sense for a sailboat, plus due to engine size a power boat has a lot more available power to tap than many smaller sailboat engines.

I agree big alternators are not a replacement for generators. My strategy is to have both big alts and a Honda to give me options.

To have a hirechy/ priority of useage. If you can manage/ juggle your useage patterns to, as much as possible, combining engine runs with big recharging or high current times.

So-
firstly Solar, to what ever capacity you have, no, fuel/ noise or maint costs, then

Engine Alternators if you can cordinate running and power demands, 'making hay when the sun shines', then

Honda, which at around $1,000 is not so expensive on maintenance costs. But of course noisy and takes gas to run. But cheaper than engine run time maintenance costs if you are not motoring anyway.

That's how I try and do it.

By the way I've 'home brewed' my Delco 28si's, with remote regulators and rectifiers, sepentine pulleys for less than a 1/10th, plus some of my time and playing around, of the $20k figure being mentioned.

I'm sure its not as fancy but I reckon its done pretty reasonably. $ per kW its actually less than a Honda 2000. I sure you can do small case units for less.

[rom]

Originally Posted by Q Xopa

I agree big alternators are not a replacement for generators

And you are wrong. What works for you may not work for others, and the other way around. Your experience is interesting nonetheless.

By the way I've 'home brewed' my Delco 28si's, with remote regulators and rectifiers, sepentine pulleys for less than a 1/10th, plus some of my time and playing around, of the $20k figure being mentioned.

Can you tell us more ? Here for example:http://www.cruisersforum.com/forums/...-204361-2.html
I have been using a 28SI myself for a year and am still not decided how to modify it !

[Q Xopa]

Originally Posted by rom

And you are wrong. What works for you may not work for others, and the other way around. Your experience is interesting nonetheless.

Can you tell us more ? Here for example:http://www.cruisersforum.com/forums/...-204361-2.html
I have been using a 28SI myself for a year and am still not decided how to modify it !

Yes agreed. Im only saying what, as you say, works for me. Not trying to suggest it is a suitable for, or anyone else should do like me.

As for being 'wrong' I usually am, and Im sure you're right. I am man enough to acknowledge that and hopefully learn from others. But could you give me a bit more of a clue specifically which bit, or everything, you are referring to that I am wrong about?

[wingssail]

Originally Posted by Dockhead

As someone above wrote, there is a lot of daylight between the propeller curve and max hp curve at normal cruising speeds; these curves only come together near or at redline.


Using that power is nearly free because the hours of amortization and maintenance have already been paid for, and you are likely getting into a better part of the fuel map, so although of course you do burn more fuel for more power it will not be proportionately more, and it might be almost unmeasurable.


I would think it would almost trivially simple to devise an alternator regulator which would automatically turn down the field current if the engine starts to get overloaded. For a fixed prop engine you could do it according to RPM; for a boat with an Autoprop you could do it with a pyrometer. Or for any boat for that matter -- a single input, EGT, would be all you would need to know, to know when to turn down the alternator.


I guess you could regulate the other end that way too -- switch on a dummy load if the EGT is too low.


This would be quite a bit cheaper than $20k.

I agree that RPM is a fair way of regulating the large alternator and I also feel that there are good reasons to avoid carrying a generator.

Not all boats or boat owners are the same, or have similar use cases. For us there is great value in avoiding the weight, complexity, and maintenance issues of a gen set. We prefer to charge batteries with the alternator on the main engine with some help from a moderate (270 watts) of solar. This has worked well for 26 years. Our Yanmar 3JH has not exhibited any symptoms of glassed cylinders, or any other engine problems. Our 6500 hours in about 50% charging only (gear in neutral, rpm at 2000, resulting in about 90-100 amps after the initial higher rate).

A large alternator would be nice, to a limited extent, if the investment was not too great..

The electrical power demand on our boat is quite low (and I am not roughing it when I am out cruising). We typically use 125Ah per day, somewhat more when on passage. Our 130amp alternator on the main engine provides plenty of electricity to keep the batteries fully charged if we are motoring much; 2-3 hours is not a long motor trip but more than enough to fill the batteries. In this event, if the regulator only increased the field current when the RPM was below, say, 2000, in most cases there would be minimum added demand on the engine since we usually motor at 2000-2200 anyhow. There not a concern that the rpm control would over tax the engine since there are no situations for us when we have to use max power to maintain 2000 (for instance when we are bashing into head winds). If there are head winds, or any wind, we are sailing; the engine is not on. We do not "motor sail". As an emergency control, the regulation to add field current when RPM is low could have a "disable" switch (like: "this is an emergency, turn off the high alternator rate.")

While sailing or anchored and needing to recharge the batteries using the main engine and a large alternator, the rpm approach seems good. The regulator would add field current, lugging the engine, until sufficient RPM is achieved (assuming the operator, me, advanced the throttle). This is a low tech solution, in keeping with my preference for simplicity, and also falls within the 80-20 rule; it's not perfect but it gives maybe 80% of the benefit for 20% of the complexity.

In the end however, it just means I can refill the batteries in 1 hour of charging, or less, instead of 1.5-2 hours, hardly worth a large investment.

Even considereing the point that we do never motor sail, there are many cruisers for which this solution would work and who have with similar needs to ours.

Most people on cruising boats do not have huge electrical needs.

Many boats do not have or want a gen set.

A larger alternator with an RPM controlled regulator would suit most people.

[Q Xopa]

Originally Posted by rom

And you are wrong. What works for you may not work for others, and the other way around. Your experience is interesting nonetheless.

Can you tell us more ? Here for example:http://www.cruisersforum.com/forums/...-204361-2.html
I have been using a 28SI myself for a year and am still not decided how to modify it !

I'm still playing around with it myself. I'm pretty much there. I've got some pics and will do a write up, for those that might be interested, when I get a bit closer to how I'm happy with it.

Is there something specific you are asking about though,- pulleys/ mounts etc? So when you say you've 'been using a 28si for a year, but not decided how to modify it'. It doesn't sound like you need to further modify if you are using it?

I am certainly happy to share with you what I have come up with so far, but it sounds like you must have worked it out already, maybe better than my solution?

[wingssail]

Originally Posted by a64pilot

However to use a prime mover as a real significant source of electrical generation will require a variable speed drive or a variable pitch prop, or you will be underpropped most of the time, because we all know how bad being way overpropped is, and if you draw off 5kw or more of power off of an average engine, that along with the normal prop load will overload the engine, so your only real choice is to prop correctly when the alternators are loaded down, and just be underpropped when they aren’t.

I don't think that is true because you don't need to be making huge amounts of power while you are also moving the vessel. As a general rule my motoring time is of a long enough duration to allow sufficient charging at a reduced rate. Making a small amount, say 1300watts (100amps by 13 volts) does not require re-propping, at least not in my case.

Save your 5kw charging for times when you are stationary or sailing and you wish to accumulate a lot of amp hours in a shorter period of time.

[a64pilot]

Originally Posted by wingssail

I don't think that is true because you don't need to be making huge amounts of power while you are also moving the vessel. As a general rule my motoring time is of a long enough duration to allow sufficient charging at a reduced rate. Making a small amount, say 1300watts (100amps by 13 volts) does not require re-propping, at least not in my case.



Save your 5kw charging for times when you are stationary or sailing and you wish to accumulate a lot of amp hours in a shorter period of time.

Well a few things, first it’s said that the primary advantage of the system is to make tons of power when underway, but then you say no it’s got to be turned down.
BTW I agree with you and not the literature, for the average cruising boat. But then you say save the 5KW of charging when your at anchor. I think it’s actually more than 5 but concede your point and that’s it’s a big boy generator at anchor.
What are you going to charge with 5000W of power? I guess a Lithium bank? More likely people are going to run airconditioners and that’s going to really rack up hours on their engines.

But we get to the crux of the issue really and that’s when underway you don’t get anything for your $20,000 that you don’t get with a big alternator for about 1/10 the money.
And when your at anchor your using your prime mover as a generator adding hours to it. So your running your big motor at anchor to make electricity. Where is this 25% fuel savings?

See I’m trying to see how it’s going to save any fuel, especially when running a much larger than required engine when at anchor to make electricity, and when motoring your having to turn it’s output down.

Now I’d bet lunch that with a “proper” generator that’s engine output is well matched to the generator, an Autoprop to optimize underway cruise and a large alternator, you come out money ahead, burn less fuel and don’t put nearly as many hours on your engine, you may run a Diesel the same number of hours, but your splitting the time between two engines and a generator is most often a less expensive piece of equipment, especially when you consider when you replace it, you replace everything, motor and generator, but when your prime mover motor needs replacing, if you want to replace the electrical generation part, well thats maybe almost another $20,000, of your generator is the Triskel.
Then there is the redundancy aspect with a generator and your engine, you have two separate ways of generating power, with the Triskel, there is no redundancy.
A 5KW Northern Lights gen, which is about the gold standard, just based on a quick Google is about $13,000, and a Nexgen is probably less than 2/3 that.

Your can make a case for this Triskel, up until you get to the point of it costing $20,000. In my opinion.

[rom]

Originally Posted by Q Xopa

But could you give me a bit more of a clue specifically which bit, or everything, you are referring to that I am wrong about?

Where you stated that an alt cannot replace a genset (because it would not work for you I suppose). The simple fact that it works for me proves you wrong. To which may answer that it is not my alt that replaces a genset but my alt+solar, and you would be right. But anyway, since you ask, I am still not buying that "with a fixed prop it doesn't matter" theory and I am still waiting for a better development from you or dockhead. You could well be right, again.


Now, attached is my yanmar 4JH4E power curve. Max 40kW or 54hp. I find myself often motoring on one engine (the other prop is folded, FoF) at a bit less than 2000RPM on flat seas, no wind. How much power does it use ? I can't tell, but I am ready to bet it is less than half. Let's say half, 20kW. The curve says max ouput at 2000RPM is 32kW. Would I be right to say that it leaves a 12kW potential for adverse weather conditions OR a big alternator ? And BTW, where does overloading the engine starts ? is it 32kW or a bit below, way below ?

[Q Xopa]

Originally Posted by a64pilot

Well a few things, first it’s said that the primary advantage of the system is to make tons of power when underway, but then you say no it’s got to be turned down.
BTW I agree with you and not the literature, for the average cruising boat. But then you say save the 5KW of charging when your at anchor. I think it’s actually more than 5 but concede your point and that’s it’s a big boy generator at anchor.
What are you going to charge with 5000W of power? I guess a Lithium bank? More likely people are going to run airconditioners and that’s going to really rack up hours on their engines.

But we get to the crux of the issue really and that’s when underway you don’t get anything for your $20,000 that you don’t get with a big alternator for about 1/10 the money.
And when your at anchor your using your prime mover as a generator adding hours to it. So your running your big motor at anchor to make electricity. Where is this 25% fuel savings?

See I’m trying to see how it’s going to save any fuel, especially when running a much larger than required engine when at anchor to make electricity, and when motoring your having to turn it’s output down.

Now I’d bet lunch that with a “proper” generator that’s engine output is well matched to the generator, an Autoprop to optimize underway cruise and a large alternator, you come out money ahead, burn less fuel and don’t put nearly as many hours on your engine, you may run a Diesel the same number of hours, but your splitting the time between two engines and a generator is most often a less expensive piece of equipment, especially when you consider when you replace it, you replace everything, motor and generator, but when your prime mover motor needs replacing, if you want to replace the electrical generation part, well thats maybe almost another $20,000, of your generator is the Triskel.
Then there is the redundancy aspect with a generator and your engine, you have two separate ways of generating power, with the Triskel, there is no redundancy.
A 5KW Northern Lights gen, which is about the gold standard, just based on a quick Google is about $13,000, and a Nexgen is probably less than 2/3 that.

Your can make a case for this Triskel, up until you get to the point of it costing $20,000. In my opinion.

Yes I, and I think many here are in agreement with most of what you are saying. Particulary with your economic arguememt.

On a slightly different approach to supplying onboard power. I recently picked myself up a cheap chinese 5.5kW (I am sceptical of that number), diesel AC genenerator. At my local welding supplier on promotion for $700. Electric start etc.

My cunning plan (I have a lot of these, some of them might even be good?), is to hook it up to my 28V 400A Military surplus. I also have a spare frame and DC gen controller and actuator.

I've got this on my project to do list. If only I had more time. But I reckon I should be able to put it together for under $2k, realistcally not pushing it too hard maybe 4.5kw. With a wet exhaust and in a sound box.

Lets see.

[a64pilot]

Originally Posted by rom

Where you stated that an alt cannot replace a genset (because it would not work for you I suppose). The simple fact that it works for me proves you wrong. To which may answer that it is not my alt that replaces a genset but my alt+solar, and you would be right. But anyway, since you ask, I am still not buying that "with a fixed prop it doesn't matter" theory and I am still waiting for a better development from you or dockhead. You could well be right, again.


Now, attached is my yanmar 4JH4E power curve. Max 40kW or 54hp. I find myself often motoring on one engine (the other prop is folded, FoF) at a bit less than 2000RPM on flat seas, no wind. How much power does it use ? I can't tell, but I am ready to bet it is less than half. Let's say half, 20kW. The curve says max ouput at 2000RPM is 32kW. Would I be right to say that it leaves a 12kW potential for adverse weather conditions OR a big alternator ? And BTW, where does overloading the engine starts ? is it 32kW or a bit below, way below ?Attachment 202579

The max you should pull from that motor at 2000 RPM is 32 KW, above that your overloaded, based on that chart.
However just like automobile engines used to be rated on a dyno not turning any accessories or running though a driveline or having to breathe through a stock exhaust, your engine or mine or anyone else’s is unlikely to have that big a gap, then that gap is going to be further significantly narrowed by the fact that your on one engine, I’m sure you realize that shutting down one engine and only running on one does something very similar to being significantly overpropped, or if your correctly propped on one, your under propped with both running.

See when you shut down one, of course the governor on the one left running will attempt to hold RPM by increasing fuel of course, so that increased load won’t be immediately apparent like it would be with an RPM drop, but of course any twin engine boat running on one motor, the engine that is running is under a much higher load.

Years ago my Father had a Little cuddly cabin boat with twin outboards, it was a decently fast boat, not a race boat but pretty darn fast. Well with one engine off but trimmed completely out of the water, it would not get onto plane with the other engine, it would easily if we changed props, but it was propped for twin engine operation of course.


Only way you would know is with a pyrometer, and ideally information from the manufacturer as to where to locate it, and max cruise temps.

[rom]

Originally Posted by Q Xopa

Yes I, and I think many here are in agreement with most of what you are saying. Particulary with your economic arguememt.

No no no , dockhead gave a pretty convincing explanation that the economics of a big alt is better than a genset in some use case and I concur. My floating condo doesn't have a genset.
BTW, a brand new yanmar 4JH57 (40kW) costs 10000 EUR inc. taxes.
3 years ago, onan 6kva option on a lagoon 450 was 17268 EUR exc. taxes.
(https://www.yanmarshop.com/product?c...&product=4JH57)