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Old 09-09-2015, 03:27   #16
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Re: efficiency of single vs twin engine

thanks all for the reply

still lot of stuff to think about
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Old 09-09-2015, 05:52   #17
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Re: efficiency of single vs twin engine

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ok don't kill me please

i know the thread has been very widley discussed but...

i was looking at the power vs liter per hour cosumption for a given boat with x shaft horsepower required to reach a y speed.

i calculate i would need about 180 shaft horse power (133kw) for my boat to reach the hull speed (displacement trawler) 46ft 35 ton (70.000lbs) 9 knots hull speed


let's the fight begin

If I am in Italy I would buy FNM HPE without any hesitation. I used to have FNM HPEP 250 with bravo 3 x diesel, best ever diesel engine I ever had, and I had a lot.
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Old 09-09-2015, 06:16   #18
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Re: efficiency of single vs twin engine

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If I am in Italy I would buy FNM HPE without any hesitation. I used to have FNM HPEP 250 with bravo 3 x diesel, best ever diesel engine I ever had, and I had a lot.



thanks, yes, i'm from italy..never heard before about this engine...i know Fiat power train (also called Iveco) marine engine, being extremely heavy duty and reliable...

but still have to find someone that can give me some price (in italy no one tell you the price via email or so on...you have to go by person and then talk about the price...maybe do 500 miles to know a price...no thanks...)

the nanni diesel are kubota based, so in theory they have common parts to find around the world
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Old 09-09-2015, 07:21   #19
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Re: efficiency of single vs twin engine

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thanks, yes, i'm from italy..never heard before about this engine...i know Fiat power train (also called Iveco) marine engine, being extremely heavy duty and reliable...

but still have to find someone that can give me some price (in italy no one tell you the price via email or so on...you have to go by person and then talk about the price...maybe do 500 miles to know a price...no thanks...)

the nanni diesel are kubota based, so in theory they have common parts to find around the world
then call them on the phone, I do not believe that they do bussiness only in personal, for your eyes only. people from ALASKA are buying FNM engines and I do not believe that Jim Smith are personally jetting off to Italy from Anchorage to enquire about price of certain engine. Must be some dealers or service agents in your local area, that is Italian engine after all.

::..FNM-MARINE....::::: Marine Diesel Engine :::::::::::....................................... ..........


I had a FNM 250 on my boat, have been very happy with it, in the 18 months that I have been running the boat, the engine has paid for itself in fuel savings ( I replaced a 5.7 V8 petrol engine).
The italians invented common rail diesel technology and have a much better handle on it than the japanese or koreans.



FNM Alaska


FNM Alaska

FNM Engine Models
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Old 09-09-2015, 07:48   #20
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Re: efficiency of single vs twin engine

thanks, i gave a look at the engine range, (over the dealer that i found being very near to me) they are all very sporty engine...i'm looking something that last 30 years and run at 1800 rpm i saw more than 100hp\liter like your engine surely very nice for sport boat but not for slow displacement trawler

however thanks for the appreciation on our italian engineering

i'll try to be more italian too and ask a dealer for a price for a FPT heavy duty engine...i saw they are widely used world wide, in brasil for example is full of them as generator


----

looking for

http://www.fptindustrial.com/product...s/N45_100.aspx


4.5 liter 4 cyl naturally aspirated 85hp, same rating as the nanni, max 3000 hours /years

too weak, would need at least 130-140 hp..

in the pleasure range

http://www.fptindustrial.com/product...s/S30_230.aspx

3 liter , same rating, 115hp, but at 3500rpm...the nanny has 0.7 liter more (3,7l) , and the same power at 2600rpm...less rpm , less wear...
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Old 09-09-2015, 08:32   #21
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Re: efficiency of single vs twin engine

An issue with engines in boats is quite a bit of the time the hull is a bigger variable than the engine. So if you can decide on a hull then move forward from there as to what the power situation will be.

"In general", most any internal combustion engine is most efficient at around 80% of maximum power output. That is why the trend for smaller turbo charged engines is popular, extra power when you need it and some economy too.

Please note, that fuel consumption is only one component in the cost of running an engine, and while I have never had an engine failure during a serious passage I have witnessed 2 that did which is something to think about.
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Old 09-09-2015, 09:09   #22
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Re: efficiency of single vs twin engine

If you concern is primarily the reliability of the motor, a relatively cheap solution (depending on the boat design) is a trolling motor.

A little 5-10hp outboard can often be enough to get you into a slip or anchored till you figure out the issue with the main engine.

And it can do double duty as the dingy motor.
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Old 09-09-2015, 10:25   #23
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Re: efficiency of single vs twin engine

thanks both

well, i was also looking at a 48v dc 20 kw ac motor..complete with controller ecc 4.000 bucks...i calculated about 4 kts for 3 hours with battery fully charged, and going 2.5 kts just with the 5kw solar...i would need at least a 20kw 48v dc generator...at this price i almost get another nanni 115hp...

..ok the tender with 15 hp outboard...maybe 3 kts at full power...in the middle of the ocean...mh..

maybe a small 30hp diesel to be used as generator with big alternator and a coupling to the propeller shaft...both the electric and this ideas at least will use the main right sized propeller...

any other ideas?
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Old 09-09-2015, 14:20   #24
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Re: Efficiency of single vs twin engine

p.s.

i've found for pratically the same price

what do you think about this yanmar vs the nanni?

http://www.yanmarmarine.eu/theme/yan...r-4LHA-HTP.pdf


nanni

http://www.nannidiesel.com/downloads....115%20ITA.pdf


the yanmar is 0.4l less displacement, but 45 hp more, espcially..

bore x stroke 100 both bore, and..nanni 120mm stroke vs 110mm of the yanmar...is a lot more long stroke, more efficient for sure!

fuel consumption looks worst for the yanmar, even with the same hp, the only pro is that it has more hp, to be used in bad sea condition...cons..it will turn at higher rpm in stead of the nanni

nanni 60 kw shaft , 1400 rpm 3 liter per hour

yanmar 60 kw shaft 1700 rpm 6 liter per hour

60 kw is the cruise required power....300rpm is 20% more...


nanni option for 160 shaft hp (this one heavy duty, while the other pleasure duty, max 3000 hours year)

http://www.nannidiesel.com/downloads...%20CR2-ENG.pdf

john deer based, bigger, 4,5 liter, 2300 max rpm, very slow..

but take a look at the turque graph...why such a big turque from 1800 to 1900, while the other 2 have a lot more flat curve...it doesn't look linear....and it's the only common rail, while the other 2 are direct igniton and mechanical...so no electronics, more reliability...

nanni n5.160 60 kw shaft 1300 rpm 6liter per hour


looks like i'm a nanni dealer but i still can't look for a better engine except 2x nanni

looking something between the 140-160 hp...40% as reserve power
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Old 09-09-2015, 15:50   #25
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Re: Efficiency of single vs twin engine

Take a look at the Nordhavn website and see how they do things if you are interested in how a trawler yacht should be set up. Also you will probably get better info on trawler engines on the trawler forum.
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Old 10-09-2015, 05:34   #26
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Re: Efficiency of single vs twin engine

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Also you will probably get better info on trawler engines on the trawler forum.
Heh... good point. Seems like some of the guys on trawlerforum.com can discuss fuel efficiency down to the milliliter per minute...



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Old 10-09-2015, 18:22   #27
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Re: Efficiency of single vs twin engine

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Heh... good point. Seems like some of the guys on trawlerforum.com can discuss fuel efficiency down to the milliliter per minute...



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That depends on whether the trawl net is full of fish or not.
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Old 10-09-2015, 19:17   #28
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Re: Efficiency of single vs twin engine

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That depends on whether the trawl net is full of fish or not.
Not that sort of trawler

https://en.wikipedia.org/wiki/Recreational_trawler
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Old 11-09-2015, 23:52   #29
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Re: Efficiency of single vs twin engine

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Yeah but I still think dragging a net full of herrings uses less fuel than a net full of snapper
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Old 13-09-2015, 05:32   #30
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Re: Efficiency of single vs twin engine

thanks all..

yeah i'm coping all the nordhawn except the wing engine

at the end i decided 2x 115 hp nanni
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