Gas v/s diesel for trawlers

So Marin and Jeff I see you didn't get the message about thread creep. Why don't you start another thread???

It's obvious to me it's a wash even though it dosn't seem like it much of the time. OK I"LL start the thread.


Re this thread topic AusCan is coming close to reality. It's an emotional thing. We buy the whole trawler as an emotional package. We run our big engines at slow speed w a special noise and that noise says "big guns". That's why they call Harley's "thunder bikes" and ride them instead of real motorcycles that are far superior because they don't sound or/and look as "heavy duty".

At one time there was the same battle going on w outboards and inboards. The inboards sounded heavy duty like Harleys and the outboards sounded like bumble bees or model airplanes but in this case common sense eventually won out. People started using their brains and mostly went to outboards and then w the new demand OB manufacturers built bigger and bigger engines until it seems they may have gone too far.

I tend to almost look for things to think about at times and started wondering why trawler owners and manufacturers were always choosing diesels when it seemed to me that other than the safety issue gas was actually better. And I figured you guys could point the way to my errors in thought. Maybe the trawler movement has a lot in common with the Harley movement.

Maybe Marin is more right than we give him credit for and "toy" is very applicable indeed. We have the latitude to think w our butt when buying toys but buying a serious thing we tend to engage a more serious part of our brain and get the right, serious and best thing. But it looks like the Harley thing is here for awhile and I'll bet trawlers will have oversized diesel engines for some time to come. Sturgis is not a gathering of engineers w plastic pocket protectors to marvel at the engineering and high tech of the Harley MC. It is however a cesspool of visual and audible emotion that screams of heavy duty.

manyboats said:

So Marin and Jeff I see you didn't get the message about thread creep. Why don't you start another thread???

It's obvious to me it's a wash even though it dosn't seem like it much of the time. OK I"LL start the thread.


Re this thread topic AusCan is coming close to reality. It's an emotional thing. We buy the whole trawler as an emotional package. We run our big engines at slow speed w a special noise and that noise says "big guns". That's why they call Harley's "thunder bikes" and ride them instead of real motorcycles that are far superior because they don't sound or/and look as "heavy duty".

At one time there was the same battle going on w outboards and inboards. The inboards sounded heavy duty like Harleys and the outboards sounded like bumble bees or model airplanes but in this case common sense eventually won out. People started using their brains and mostly went to outboards and then w the new demand OB manufacturers built bigger and bigger engines until it seems they may have gone too far.

I tend to almost look for things to think about at times and started wondering why trawler owners and manufacturers were always choosing diesels when it seemed to me that other than the safety issue gas was actually better. And I figured you guys could point the way to my errors in thought. Maybe the trawler movement has a lot in common with the Harley movement.

Maybe Marin is more right than we give him credit for and "toy" is very applicable indeed. We have the latitude to think w our butt when buying toys but buying a serious thing we tend to engage a more serious part of our brain and get the right, serious and best thing. But it looks like the Harley thing is here for awhile and I'll bet trawlers will have oversized diesel engines for some time to come. Sturgis is not a gathering of engineers w plastic pocket protectors to marvel at the engineering and high tech of the Harley MC. It is however a cesspool of visual and audible emotion that screams of heavy duty.

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Eric - Well Said!

Trawlers are "working man" boats, and diesels are "working man" engines. Grunt grunt

Good Lord , have you never been aboard a Marine Traider (just to name one).

Working man, Ho, Ho, Ho, Gin Palace might be closer.

Working boats GO OUT in some rotten weather ,to work,

the scantlings of most "trawler yachts" precludes most open ocean operation .

Well, lets look at some specifics:

A new Mercruiser/Crusader/Volvo 300 hp V8 is going to cost about $12K. A new Cummins QSB 380 is going to cost $30K. All other costs to install each are about the same. Each are capable of producing 200 hp continuosly but the gasser won't last near as long at that power level

Over a ten year period of 200 hours per year of use cruising fast and using the 200 hjp the M/C/V is going to burn 33,000 gallons of fuel and that will cost about $130,000 (whoever said fuel was a small part of boating). And it will be ready for replacement.

Over the same ten years the diesel will burn about 20,000 gal of fuel and that will cost $80,000. And that engine will be good for thousands of more hours.

So the $18,000 initial cost premium is paid out almost three times over in fuel savings. Yes the diesel costs a bit more to maintain- increased oil capacity and more frequent changes. But that difference is dwarfed by the fuel differences.

But nobody operates their gasser that way. Anyone who would buy a gas powered cruiser, can't afford the fuel if they were to run it that way. Most gasser express cruisers probably spend less than 50 hours per year at 200 hp. Most of them idle through the anchorage, showing off with the stereo blaring and the passengers hoppin and boppin (is there a more modern term?).

So it is an interesting debate about which is better. It all depends on how you are going to use the boat.

If you are going to run at displacement speed producing less than 50 hp then the diesel's relative advantage improves (diesels maintain their BSFC at low loads better than gassers) but the absolute numbers drop to the point that the gasser probably comes out equal over a ten year period.

And the comparison probably favors the gasser if you compare a 100 hp outboard to a 100 hp diesel both producing less than 50 hp to cruise at displacement speed.

David

Well put march but that's only part of the picture not to belittle your post at all as it gives good scope to this issue but something more important may/could be ten years of smooth and relatively quiet boating. 1000 hours of pleasure x 2 or better.

But a better move could be $1000 worth of good sound insulation but you could throw the $1000 insulation at the gas engine just as easily...???

My frame of mind when I started this was just to see if gas was an option that had any chance of being a good move. The resale value and the safety issue takes the possibility off the table but it is fun to think about.

If I was going to repower Willy w a gas engine what I'd want would be the Plymouth Arrow engine that had balancers so it was as smooth as an V8 above an idle. They called it the "silent shaft" because the lack of vibration stopped the mechanical drumming noise in the car that all 4cyl cars have. Don't know if I could get parts for it though and all the marineizing would need to be custom one off stuff. For that matter I could go w a small Buick straight eight and be smoother and quieter yet. But my Mitsu is just fine.

Wow. Plymouth Arrow and Buick Straight-Eights. Now there are some readily available, practical, easily maintained engines for you. Parts in every store, too.

I think David summed it all up very nicely.

If diesels didn't make sense for the market, the manufacturers wouldn't be putting them into their boats. The people you need to ask your questions to, Eric, are the ones who started this whole diesel cruiser business in the first place. American Marine, Kong & Halverson, etc. And for the most part, they're all dead.

American Marine in their literature in 1966 about their then-brand-new Grand Banks line of boats talked about diesel economy and diesel dependency. In fact that was their company slogan--- Dependable Diesel Cruisers. They didn't talk about speed and they didn't talk about a burly-man image if you bought one of their boats.

Perhaps the diesels they were using were more economical and dependable than the gas engines available to power the same size boat back then. I don't know, I wasn't there.

But AM, in analyzing the potential market for this kind of boat, probably didn't put much stock, or even think about, any sort of macho psychology on the part of their buyers that would lead them to buy a diesel boat over a gas one.

They (in my opinion) were simply trying to manufacture a roomy, seaworthy, well-made cruising boat that was economically powered with an engine or engines that were very reliable and long lived. They weren't building boats with the idea they would be discarded in a few years. In fact I seem to recall reading copy in some of their brochures about a boat that could be "handed down from generation to generation," or something like that. They were building for the long haul, not a throw-away society like we have now.

With the advances in gas engines maybe they make more sense in whatever it is that today's buyers want out of cruising boat. I don't know. We bought a boat made in the early 70s. As such, we bought into the original philosophy behind American Marine's Grand Banks line. Whether that philosophy is still valid you'll have to ask the folks at Nordic Tug and American Tug and Grand Banks, Llc, and Mainship and the like today.

And what's this silliness about Harley-Davidsons not being real motorcycles? I'd love to see you dig up Bill Harley and Arthur Davidson and try to explain that one.

Put gasoline engine(s) in your speed boat, but not in my slow, long-range recreational trawler. Diesel-power works for me.

I wanted a diesel because ... well, just because. Rational? Maybe, maybe not. But what does logic have to do with someone like me buying a boat anyhow?

Marin wrote

"if diesels didn't make sense for the market they wouldn't have but them in"

Nonsense Marin. They put whatever they thought the "market" WANTED. The consumer designs the product and the engineers make their wishes work. You rarely get an ideal product. You get what other people want.

re the old engines I did say they prolly wouldn't fly .... Just dream'in/think'in.

manyboats said:

Marin wrote

"if diesels didn't make sense for the market they wouldn't have but them in"

Nonsense Marin. They put whatever they thought the "market" WANTED. .

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That's what I just said. Making sense for the market means making what the market wants. Otherwise, you won't sell anything.

Eric, Marin... Re, making sense of the "pleasure boating" market:

Compared to diesel there in general seems to be more gasoline engines in “cabin cruiser” boats up to about 40', especially those with planing hulls... such as mine! (not counting ski boats and other non-cabin speedsters). Above the 40’ range gassers die way off and diesel torque takes center stage. Above 50' gas is all but gone! Also for cabin cruiser full displacement hulls of most lengths diesel are often the engine of choice. Being accustomed to both engine types I’m comfortable with either. I’m actually getting ready to put offer on a craft with twin 160 hp turbo charged Lehmans. Reason I say this is because both power sources sure have their place in the marine industry.

BTW – Marin, your GB diesel engines same as the ones I’m contemplating buying?

Cheers! And, Happy Holidays!! - Art

Art said:

BTW – Marin, your GB diesel engines same as the ones I’m contemplating buying?

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Our engine operating manual covers three versions of the "FL 120." These engines are based on the Ford of England Dorset diesel. There are a lot of subtle cubic inch variations in these engines and they're easy to overlook.

The first one is the" FL80." It's based on Ford of England's four-cylinder version of the of the engine called the 2712-E. It is a 254 cu in engine and develops 80 hp @ 2,500 rpm.

The second version is what we have,the "FL120." It is based on the Ford of England 2715-E six cylinder, 380 cu in, naturally aspirated diesel. It develops 120 hp @ 2,500 rpm.

The third version is the turbocharged version. Ford called it the 2704-ET. It is a six-cylinder, 363 cubic inch, turbocharged engine that develops 150 hp @ 2,400 rpm.

The Lehman model numbers for the marinized versions of these engines are 4D254 for the 80 hp four cylinder, 6D380 for the 120 hp six-cylinder engine, and 6D363T for the 150 hp six-cylinder turbocharged engine.

Lehman of New Jersey marinized a lot of different engines over the years, a number of them from Ford of England. As the turbocharged engine you are describing is 160 hp, I suspect it's not one of the three I listed above.

Lehman also marinized the later Ford of England Dover engine. This is the base engine for the "Ford Lehman 135." Lehman actually called them "SP" engines for "Super Power." Ford of England made four variants of this engine.

The Ford (and Lehman) numbers are:

2722E (Lehman model SP90), four cylinder, 254 cu in, 90 hp @ 2,600 rpm.

2725E (Lehman model SP135), six cylinder, 380 cu in, 135 hp @ 2,600 rpm

2726E (Lehman model SP185), six cylinder 363 cu in turbocharged, 185 hp @ 2,500 rpm

2728E (Lehman model SP225), six cylinder 363 cu in turbocharged, 225 hp @ 2,450 rpm

2728E (Lehman model SP275) six cylinder 383 cu in, turbocharged/intercooled, 275 hp @ 2,500 rpm

Again, no 160 hp turbocharged engine in this group. So I don't know what Lehman engines are in the boat you are considering.

The above data was taken from our FL120 manual and the SP-135 manual on the GB owners forum.

markpierce said:

Well, doesn't diesel contain more energy than gasoline for a given volume?

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yes, D 147,000BTU's per gal and gasoline 125,000 or if reformulated 114,000btu's

Marin said:

Our engine operating manual covers three versions of the "FL 120." These engines are based on the Ford of England Dorset diesel. There are a lot of subtle cubic inch variations in these engines and they're easy to overlook.

The first one is the" FL80." It's based on Ford of England's four-cylinder version of the of the engine called the 2712-E. It is a 254 cu in engine and develops 80 hp @ 2,500 rpm.

The second version is what we have,the "FL120." It is based on the Ford of England 2715-E six cylinder, 380 cu in, naturally aspirated diesel. It develops 120 hp @ 2,500 rpm.

The third version is the turbocharged version. Ford called it the 2704-ET. It is a six-cylinder, 363 cubic inch, turbocharged engine that develops 150 hp @ 2,400 rpm.

The Lehman model numbers for the marinized versions of these engines are 4D254 for the 80 hp four cylinder, 6D380 for the 120 hp six-cylinder engine, and 6D363T for the 150 hp six-cylinder turbocharged engine.

Lehman of New Jersey marinized a lot of different engines over the years, a number of them from Ford of England. As the turbocharged engine you are describing is 160 hp, I suspect it's not one of the three I listed above.

Lehman also marinized the later Ford of England Dover engine. This is the base engine for the "Ford Lehman 135." Lehman actually called them "SP" engines for "Super Power." Ford of England made four variants of this engine.

The Ford (and Lehman) numbers are:

2722E (Lehman model SP90), four cylinder, 254 cu in, 90 hp @ 2,600 rpm.

2725E (Lehman model SP135), six cylinder, 380 cu in, 135 hp @ 2,600 rpm

2726E (Lehman model SP185), six cylinder 363 cu in turbocharged, 185 hp @ 2,500 rpm

2728E (Lehman model SP225), six cylinder 363 cu in turbocharged, 225 hp @ 2,450 rpm

2728E (Lehman model SP275) six cylinder 383 cu in, turbocharged/intercooled, 275 hp @ 2,500 rpm

Again, no 160 hp turbocharged engine in this group. So I don't know what Lehman engines are in the boat you are considering.

The above data was taken from our FL120 manual and the SP-135 manual on the GB owners forum.

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Thanks Marin, for comprehensive info. I'll copy and place in folder. Let you know outcome after I visit to survey... maybe purchase?? - Art

BaltimoreLurker said:

I wanted a diesel because ... well, just because. Rational? Maybe, maybe not. But what does logic have to do with someone like me buying a boat anyhow?

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For me, it's as simple as that. If you want a diesel...get one. Do you need a diesel--only if you want one.

jeffnick said:

For me, it's as simple as that. If you want a diesel...get one. Do you need a diesel--only if you want one.

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I want an electric motor diesel trawler!......

Bfloyd--- As you know, people have done these. There is at least one Grand Banks I know of that has been converted to diesel-electric. But in the few write-ups I've read about these conversions, while they worked just fine, the cost of the components, control system, and conversion itself far exceeded any economical benefits that were being realized by the boats' operation.

The conclusions were that other than as a technical excercise and proving a concept, it was not an economically viable thing to do with cruisers like most of us have. Much, much less expensive even over many years to simply run the boat in its original form as a diesel.

I want an electric motor diesel trawler!......

And the boating industry wants you to have one!

Remember a new boat has a 20-25% markup , so an extra $50K -100K for a marginal , power your boat for 10 miles system , will add considerably to the builders and dealers take.

Yup ..... Diesel-Electric is like a good anchor ..

They cost more but ther'e worth it.

But availability and service is very questionable. They may not be available at all now.

Ideally we would pick the number of screws and engines independently.

Marin said:

Bfloyd--- As you know, people have done these. There is at least one Grand Banks I know of that has been converted to diesel-electric. But in the few write-ups I've read about these conversions, while they worked just fine, the cost of the components, control system, and conversion itself far exceeded any economical benefits that were being realized by the boats' operation.

The conclusions were that other than as a technical excercise and proving a concept, it was not an economically viable thing to do with cruisers like most of us have. Much, much less expensive even over many years to simply run the boat in its original form as a diesel.

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Good morning Marin, everyone. I have yet to find any account of these experiments and am very much interesdted in trying out the Santa Ana Defever come home belt jackshaft driven electric motor come home system which is claimed will drive the boat under ideal conditions at 5knts. I would be one of the last people to ever believe advertiseing claims but the above was writen up in a 1980 edition of Sea Trials. I can email you a copy if your interested? I was fortunate to have worked with engineering staff from Ford, toyota, GM, when these companies submited prototype electric vehicles to CARB for approval. GM's EV1 in my opinion was light years ahead of all the others and i was sorely disapointed when they did not offer it for sale only on a lease. That electric car was only a two seater but it was a rocket ship with every luxury doo dad you could think of included as standard. The EV1 even had a heads up display and as far as i know she still holds the land speed record for electric cars. Her top speed was limited to 80mph and she would do that in 6 sec's. if i remember corectly
Anyway, my experiance back then got me to thinking of a system that would be applicable for pleasure craft. I did notice that west marine has in their 2012 catalouge electric propulsion systems both inboard and outboard for sale. There is no escaping the fact that electric motors have more low end torq than any other engine.

Thanks for your thoughts Marin

Best wishes
Britt

How about diesel - hydraulic?

jeffnick said:

How about diesel - hydraulic?

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I'd rather deal with an electrical spill than an oil one.

One can do just about anything w hydraulics and valves. Put engines wherever you want them and the screws wherever you want them too. Perhaps a very clever triple screw boat w inline engines mounted crossways w the drive ends inbd. One could make the ctr screw with a lockable 2 blade prop that could "hide" behind the "deadwood" at the end of the keel. A gold mine of daydreaming here but of course the hydraulic losses would reduce the efficiency but if a clever enough system was drummed up overall efficiency could be reclaimed or even bettered. There are some transmission losses in a regular gearbox too but much smaller. And a given w hydraulic drive would be isolation of the vibration of the engine/s from the drive shaft/s. No need for Aqua Drive.

bfloyd4445 said:

Good morning Marin, everyone. I have yet to find any account of these experiments and am very much interesdted in trying out the Santa Ana Defever come home belt jackshaft driven electric motor come home system which is claimed will drive the boat under ideal conditions at 5knts. I would be one of the last people to ever believe advertiseing claims but the above was writen up in a 1980 edition of Sea Trials. I can email you a copy if your interested? I was fortunate to have worked with engineering staff from Ford, toyota, GM, when these companies submited prototype electric vehicles to CARB for approval. GM's EV1 in my opinion was light years ahead of all the others and i was sorely disapointed when they did not offer it for sale only on a lease. That electric car was only a two seater but it was a rocket ship with every luxury doo dad you could think of included as standard. The EV1 even had a heads up display and as far as i know she still holds the land speed record for electric cars. Her top speed was limited to 80mph and she would do that in 6 sec's. if i remember corectly
Anyway, my experiance back then got me to thinking of a system that would be applicable for pleasure craft. I did notice that west marine has in their 2012 catalouge electric propulsion systems both inboard and outboard for sale. There is no escaping the fact that electric motors have more low end torq than any other engine.

Thanks for your thoughts Marin

Best wishes
Britt

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Britt

What I do not get, regarding efficiency value, is the "energy-loss-transfer" that must occur. If energy is created by petrol engine and transferred directly to electric engine, or for even more energy loss factors stored in battery first and then transferred to electric engine, the overall efficiency values as compared to energy directly from petrol engine to prop-shaft must be diminished. The only way I can see there being increased overall efficiency via marine electric motor propulsion would be if the "free" solar energy could be captured sufficiently to upset the general physics property of "energy-loss-transfer".

It seems clear to me: If it can be figured out how to get increased energy (as compared to power produced via fuel burned in petrol engine) from the electric motor to the prop shaft without including solar energy as an offset to "energy-loss-transfer" then the basics of perpetual motion has been established... wherein all "extra energy" needs should be able to be accomplished in utility scale.

Merry Christmas and Happy New Year! Art

Dupe - sorry!

If I cruise 10hours in idle , I must full power at least 1minute twicw a day to clean the engines. Is it the same with gasoline engines?

The reviews and opinions I have read had to do with converting existing diesel-powered boats like the Grand Banks to diesel-electric. So the observations of the conversion cost not being repaid by the operating savings had to do with converting an existing diesel cruiser.

The cost benefit of creating a brand new boat with diesel-electric propulsion is another matter. How this would affect the selling price of the boat as compared to the selling price of the same new boat with conventional diesel propulsion would be the interesting thing to know.

I am sorry but I don't see any efficiency advantages to diesel/electric or diesel/hydraulic over a prop shaft driven by an engine through a transmission.

Transmission energy losses are about 3%. There is some loss in efficiency due to the prop shaft angle (which presumably can be horizontal on an electric or hydraulic drive) but it can't be more than 10%. So the overall efficiency is 97*90 = 87%.

A hydralic pump has an efficiency of 85-90% and the drive motor has a similar efficiency. So the overall efficiency is at best 90*90 or 81%.

A 50 KW generator probably has an efficiency in the same ball park as the hydraulic pump. But you have to rectify the AC produced and that is at least a 5% loss. The DC motor has about the same efficiency as the hydraulic one.

Niether beat a direct drive prop shaft for efficiency.

The primary appeal to a diesel/electric system is to store some of that energy in a battery to use without running the diesel and supplement it with solar. But it takes real estate for solar power and lots of weight for batteries.

David

Alemao said:

If I cruise 10hours in idle , I must full power at least 1minute twicw a day to clean the engines. Is it the same with gasoline engines?

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Not exactly, I don't believe. If gas engine is in good condition and tune while burning clean, fresh gasoline its plugs should not foul and carbon should not build on valves or cylinder-piston heads because the gasser develops and maintains substantial internal heat conditions, even at idle. That said... I do not run on idle for many hours at a time (one to two at most, and seldom at that). 10 hours running on idle (considering it is 600 to 700 rpm on a gasser) would be past my experience for not fouling an engine. I will run at pretty slow speeds for long duration hours turning some 1400 to 1900 rpm and experience no problem.

What rpm do you run on idle? Many types/makes of diesel do need to be “blown out” sequentially when running “cool”, i.e. at low rpm. I never heard of “one minute” being ample “heat-up” duration before... seems more like 10 to 15 minutes are usually recommended. Your engine manufacturer recommend the one minute higher rpm each five hours or so for blowing it clear?

manyboats said:

One can do just about anything w hydraulics and valves. Put engines wherever you want them and the screws wherever you want them too. Perhaps a very clever triple screw boat w inline engines mounted crossways w the drive ends inbd. One could make the ctr screw with a lockable 2 blade prop that could "hide" behind the "deadwood" at the end of the keel. A gold mine of daydreaming here but of course the hydraulic losses would reduce the efficiency but if a clever enough system was drummed up overall efficiency could be reclaimed or even bettered. There are some transmission losses in a regular gearbox too but much smaller. And a given w hydraulic drive would be isolation of the vibration of the engine/s from the drive shaft/s. No need for Aqua Drive.

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whoaaa........i gotta thunk about this un....Ah, i got it, so simple why didnt i see the answer at first glance. The engines go in the keel and drive a system of pulleys and the mast via a system of clutches and gears controlled electronically via a computer. You boot up your pc, enter your destination and allow the computer to do the rest. A small single electric motor and electric solenoid controled switches should do the trick. Most of the energy to propell the vessel will be provided by him/her up there and the small left over can be provided by a small generator driven electric motor.........................................................................................
Didnt someone make a schooner like this back in the early years of this century? she had three masts computer controlled i beleive