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Old 11-15-2013, 08:53 PM   #1
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wing engine/generator combo

Currently my 42 Krogen has a 12kw Westerbeke (way too big) to drive a hydraulic get home (spinning main shaft). Seems from PO paperwork to never have worked well.

I have looked at several "electric back up propulsion" solutions, and am not satisfied for one reason or another. I plan to venture to South America etc. (hence the want for axillary propulsion).

My thoughts are:

Instead of $$ for new gen, new wing engine, etc. Why not use the wing engine to drive a 5-8kw belt drive gen. This would keep the wing regularly exercised and kill two birds with one stone, still having the mechanical propulsion.

Sizing:

Yanmar has a 15, 20, 30. Most Krogens have the old 27. (First hand experience please chime in on performance) my thoughts are 8KW = 10hp if 746 watts = 1 hp minus losses etc. So to keep wing properly loaded in gen mode, I'd prefer the smaller yanmars. Relizing no Krogen Lehman owner ever admits to actually using the wing for propulsion, the smaller engine would probably be fine. This boat pretty much coasts down wind.

Please keep your response to first hand knowledge, experience and not speculation.

Thank you
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Old 11-16-2013, 12:26 AM   #2
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Please keep your response to first hand knowledge, experience and not speculation.

Thank you
First post and you throw the gauntlet. I cannot answer your speculations and guesses with facts that fit your ideas. But with a bit of knowledge I do have the POs lack of success is telling you something about the minimal get home concept.

You may want to keep it simple and do like many KK42 blue water owners and eschew the mini get home concept and keep adequate spare parts, increase your mechanical skills and rigorously practice preventative maintenances by the book. Or just put in a adequate get home engine with its own shaft and prop.

BTW, welcome to the Forum
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Old 11-16-2013, 06:32 AM   #3
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Sealife

Bay Pelican, a Krogen 42, has both a 8kw generator and a 27 hp Yanmar back up with its own shaft and prop. As part of the Yanmar's "exercise program" we regularly use the Yanmar for propulsion although to a limited extent. Whenever entering a harbor where we would normally slow down (cruise is 6.5 to 7 kts) we switch to the Yanmar which nicely moves us along at 4 kts. We do the same when leaving the harbor. The Yanmar is always on when entering and leaving a crowded anchorage in case we have to maneuver.

Benefits of the Yanmar on the Krogen:

When maneuvering such as docking or anchoring allows me to swing stern to port (main backs to starboard).

Have a 150 amp alternator allows us to charge the batteries if the genset is down.

Will be used as a backup if the main goes down for something other than fuel. (This hasn't happened in 15 years.) Air in the fuel line brought everything down once.

The key is to exercise these engines.

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Old 11-16-2013, 07:30 AM   #4
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IF you have a wing engine with a hyd pump, it is ideal.

Turning the main shaft , easy, operating a hyd generator head at the correct speed , easy , a bow thruster that wont overheat in 30 to 180 seconds easy., 24v 300A lat for rapid battery charging , easy.

The best part is with a hyd pump ALSO on the main engine rapid battery charging , 4 or 6 KW of Ac power (or more) , the windlass will still work.

The wing engine may need to be on for the bow thruster as the main would usually be at idle while docking.

Hyd can be repaired world wide , electric stuff has to be flown in world wide.

>Please keep your response to first hand knowledge, experience and not speculation.<

Good luck with that , few have built boats with this requirement or re-outfitted inshore cruisers to operate independently for distance use .

IF the hyd drive setup is not doing the job , remember it takes about 2 HP per ton (2240lbs) to operate near LRC .Probably 5.5 to 6K

12KW is perhaps 15HP and hyd looses 5%-10% at the pump and again at the motor .

With that reality either a slower emergency speed will need to be accepted or a far larger engine installed. Only 1 HP per ton should give 3 K or so , 75 miles a day will get you to a repair facility , although it might take a week or 10 days , depending. A 50 HP engine might get to LRC.

Good luck in finding ANY folks that have done this complete rebuild / modification them selves , or even a yard with this experience..

Weather electric or hyd a belt or chain , the shaft needs a certain HP for any speed.
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Old 11-16-2013, 08:26 AM   #5
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Quote:
Originally Posted by Sealife View Post

Currently my 42 Krogen has a 12kw Westerbeke (way too big) to drive a hydraulic get home (spinning main shaft). Seems from PO paperwork to never have worked well.

...

Instead of $$ for new gen, new wing engine, etc. Why not use the wing engine to drive a 5-8kw belt drive gen. This would keep the wing regularly exercised and kill two birds with one stone, still having the mechanical propulsion.

Have you attempted to make the Westerbeke work well? If it can be made to function properly...

What exactly about the Westerbeke would make "way too big" worth the cost of complicated refit?

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Old 11-16-2013, 09:32 AM   #6
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Our wing is a 56HP Yanmar coupled to a Yanmar SD50 Saildrive with folding prop. Pushes our 47ft 65,000lb Selene at about 4Kt depending on conditions. Not sure whether a smaller engine would do the job? On the other hand the folding prop is small compared to the main prop, so this may be a bigger impact.
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Old 11-16-2013, 09:46 AM   #7
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IF you have a wing engine with a hyd pump, it is ideal.

I like FF's idea. I do not know the efficiencies of hydraulics, but from a technicial standpoint it would not be difficult.

Tie a prime mover (engine) directly to a hydraulic pump.

Use a hydraulic motor to run a generator end. Control the speed of the hydraulic motor using a standard electric governor, tied to a variable flow valve.

I do not know if hydraulic motors can be purchased with SAE bellhousings and flex plate adapters. If they can you can use a single bearing generator end. That would be preferable. Worst case you could use a two bearing generator end. That solves the AC power needs.

Use a second hydraulic motor to run the get home shaft and prop.
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Old 11-16-2013, 10:01 AM   #8
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I like FF's idea. .
In general it is OK. But with the KK42 already setup and designed for a nice simple wing engine, why argue with success?

There are some interesting debates today among the new KK52 owners as to what combination to choose during the build - twin or single JDs and if single - with or without wing engine.
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Old 11-16-2013, 11:13 AM   #9
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You 12kw gen is not to big. Probably the wrong hydraulics. Is the hydraulic motor varible psi drive? Might want to look at the hydraulics. I wish the Eagles gen set motor had more hp.
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Old 11-16-2013, 01:26 PM   #10
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Thank You for all the input thus far. I apologize if I seem a bit abrasive, but come seeking an exchange of technical ideas, not socialization. I don't think this violates any forum rules, nor am I condemning such interaction.

That said:

I am a very competent mechanic, and will have plenty of spares. I am a belt and suspenders kind of a guy. I realize the speed won't be there, but I will be able to maintain course while repairs are made if nothing else (according to FF calculations 20 HP will get me 3 knts). Slow forward progress would be acceptable, as it beats the alternative.

Marty, what rpm are you at when traveling at 4 knots? (I could look at a HP chart and figure required hp)

I do not have nor do I intend to install a thruster, so not a benefit of hydraulics for me. Although I do like the idea of driving 2 pumps for Gen and separate shaft. Problem is why tolerate the losses and complexity if I can direct couple a shaft and belt drive a gen?

I also don't want to drive main shaft. If transmission thrust bearings, over temp, mounts, prop, etc. go bad, I'm still SOL.

Finally, the 12kw gen works fine, It is too large to be properly loaded for AC production which is 99% of the time. My boat is being set up to be "energy independent" for several other reasons (thanks Marty for the 50hz heads up), and therefore will most likely not require the use of a gen anyway. Hence the wing engine/gen combo for justification of expense/ back up.

Thank you, and please keep the input coming. And to "throw down the gauntlet" again: Please keep on topic regarding the original post.

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Old 11-16-2013, 02:52 PM   #11
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In general it is OK. But with the KK42 already setup and designed for a nice simple wing engine, why argue with success?

.
No argument there. No need to reinvent the wheel.

while I am not familiar with the kk42 first hand, it seems that there are very few that have wing engines. At least from the yachtworld listings.
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Old 11-16-2013, 04:46 PM   #12
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No argument there. No need to reinvent the wheel.

while I am not familiar with the kk42 first hand, it seems that there are very few that have wing engines. At least from the yachtworld listings.
Bay Pelican is the only KK42 that we have met that has a wing engine. I'm sure there are a few more of the 200+ KK42s made but the wing engine was not a factory option so each one is probably different with different degrees of success. I agree with Sunchaser's second post, "...keep adequate spare parts, increase your mechanical skills and rigorously practice preventative maintenances by the book..."
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Old 11-16-2013, 04:52 PM   #13
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Again, despite the theoretical 20HP, I would strongly advise against investing a decent amount of money to end up with only a 20HP system, no matter how you engineer it. You might as well plan on tying you dinghy to the side of the KK and carrying enough gas to get you home. It is not a matter of speed (3 vs. 4kt). It is a matter of needing your standby system to allow steerage under bad sea/wind conditions. Sh1T usually happens as the worst of times. So, either do it right or forget it!!
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Old 11-16-2013, 06:39 PM   #14
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When we operate the Yanmar 27 hp at speed (4kts) we are generally at 2200 rpm.

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Old 11-16-2013, 09:01 PM   #15
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Sealife: I've thought deeply about the ramifications of installing various means of alternative propulsion with my Manatee, mostly due to worries from the Admiral. I don't plan on taking my Manatee farther than the Bahamas, but if I were, I'd buy me a Yanmar 27 or 36 HP long-shaft diesel outboard, put it on a bracket and use it for my dinghy engine too. They are not sold new in the US (due to EPA), but I've seen two in Tortolla and two in Nova Scotia. Yes, they are not cheap, but you can take it to your next boat or sell it separate, and parts are through Yanmar network everywhere. Fuel hook-up to your tanks is no more difficult than any other outboard. Remans are also available from UK. Have it sent to British Virgin's on your first excursion. My two cents.
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Old 11-16-2013, 09:58 PM   #16
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For a hydraulic bow thuster and reason get home 35hp is not enough. If you have enough hp the hydraulic is key importance.
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Old 11-17-2013, 03:21 AM   #17
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I'd vote for HealHustler's pragmatic & creative solution at post #15.
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Old 11-17-2013, 05:50 AM   #18
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Just another option for you to consider. Two parts: If you want a back up engine then you can go the normal route and install a small Yanmar with its own shaft and a Max prop.

As to electrical generation, if the current 12kw unit is in good shape keep it. If the underloading problem is an issue for you then add a second and even better a third charger. Using two chargers I am able to put a better load on my 8 kw. generator. Three chargers would be better of course for a 12kw. Assuming you had 12 Trojan 105s as a battery bank you could have one charger for each four batteries. This would be within the maximum charge rate allowed for the batteries and would cut down on your generator run time.

An alternative is to add an AC watermaker and run it whenever the generator is on. Similar alternative is a holding plate refrigeration system recharged whenever the generator is on.

The underloading issue is discussed frequently.I have a friend with a 12kw who runs the air conditioning in unoccupied staterooms just to load the generator when he is charging batteries.

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Old 11-17-2013, 06:53 AM   #19
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>I can direct couple a shaft and belt drive a gen?<

Belts eat power too , sorry no free lunch.

With only a 12KW engine the HP delivered to a shaft will be minor , hopefully enough for good steerage.

In the wing engines I have seen the folding prop was not properly matched ,,usually too small with too little blade area.

These are expensive , but the difference between 2K and 3K , or 3K and 3.5K is worth considering.

I would get a GPS and do a log of engine speed vs boat speed on the wing engine to see if there may be improvement.

>Finally, the 12kw gen works fine, It is too large to be properly loaded for AC production which is 99% of the time. My boat is being set up to be "energy independent" for several other reasons (thanks Marty for the 50hz heads up), and therefore will most likely not require the use of a gen anyway<

Energy independent usually translates to a propane range, reefer and HW.

If the attempt will be with an acre of solar and noisy wind machine and 2000lbs or more of batteries there is still a need for charging beyond what wind or sunshine can bring.

With a big alternator (24V - 300A) the batts can be rapidly refilled and 4KW of AC is easily available.

Happily this combination does not need a constant speed to operate properly , so small charge or house loads can be done with lower RPM.
The Higher loading is more efficient than minor load a a constant speed.

No shore or noisemaker powered batt charger has the power of a BIG alt with a smart V regulator .

While a Krogen is a fine cruiser , it is in no way an offshore passage maker , except in the finest weather.

40K and 15 seas is a minor storm , how do you plan ob getting to SA? Coastal , long shore from T Dad on down?.
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Old 11-17-2013, 10:14 AM   #20
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[QUOTE=FF;192268

Energy independent usually translates to a propane range, reefer and HW.

[/QUOTE]


I suspect switching from electricity to propane isn't really achieving energy independence

OTOH, if there's boatloads of propane aboard, perhaps a propane-drive outboard (Lehr's impending 15-hp?) on a bracket might be worth investigation. Especially if the genset's size and loading issues can be solved more easily without the get-home in the mix.

Sort of a cheaper version of Healhustler's diesel outboard idea...

Not a recommendation, just an observation...

-Chris
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