Gas engines / verses Diesel on larger boats ??

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For about the hundreth time (okay I might exaggerate a bit here), I will link the David Pascoe article, almost all discussion questions and suppositions are answered there. For example, the comment below is answered quite well by David:

I'm going to assume the guts of these engines is all the same, so I'd further assume the D3-110 running at full load would be MUCH more durable and long lasting than the D3-220 running at full load. Sound about right?

So says, regardless of modern technology, or maybe because of it, engines don't last as long. He basis is reflected in the old adage - "there is no replacement for displacement." One enemy of engines is heat, so a block engine that supports 100 versus 200 hp is going to last longer in the smaller version. Using turbochargers is a no no according to David, and he is anti-aluminum; all for the same reason - heat.

Someone here was talking about a 454 block engine kind of being maximum for gas engines. Mercury has done away with their smaller stern drive engines and has now only three block sizes, with two hp's available in each block.

I just installed a new Merc 6.2 l which is 378 cubic inches. The new Merc 8.2 l which is 500 cubic inches is the largest other size available.

And so to parrot Pascoe's reasoning, for boats over 34 feet the owner is best owning a diesel engine, under 35 feet a gas engine. This equation based on heat, torque, expense and rebuilds, servicing, life expectancy of the engines and fuel burn.

Here are the inboard Merc engines now available in their own engine build (not an auto engine as they used previously and Volvo still does):

https://www.mercurymarine.com/en/ca/engines/inboard-and-sterndrive/mercruiser/

And for the exaggerated 100th time, David Pascoe's articles:

https://www.yachtsurvey.com/GasDiesel.htm
 
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The anti-turbo thinking is pretty outdated IMO. Plenty of turbodiesels run for many thousands of hours (and with better efficiency than an NA diesel of equivalent hp).
 
I find David Pascoe's articles interesting, but they are somewhat dated (the diesel one is 20 years old). Although I don't know enough to disprove the following, I am somewhat skeptical that:

"The average life expectancy of a marine diesel engine in a pleasurecraft is somewhere around 1500 hours between major overhauls. The average boat reaches this in about 8-10 years, meaning that the average annual operating time averages around 150 hours. If that seems unrealistically low, consider that that translates into 2-1/2 weeks of eight hour days. Most boats have years when its even less than that. If this surprises you, it may surprise you even more when I tell you that gas engines average around 900 hours before overhauls."

I would expect the numbers to be double of what he notes above, at least for well-maintained engines. Given how poorly many folks maintain their boats (at least mechanically) maybe his numbers are still valid after all this time?

And regarding boat size for diesels, it all depends on what the customer for the boat wants. Many Ranger Tugs owners seem quite happy with the diesel engine in their 21 foot boats!


Jim
 
Toki said:
So, I think this thread has drifted enough for me to ask a semi-unrelated question.

My Ranger 27 contains the Volvo-Penta D3-220. This same basic engine is available from 110 HP up to my 220 HP. I've heard differing explanations of how the same engine can span such a range of rated HP. Here's some questions:

I'm going to assume the guts of these engines is all the same, so I'd further assume the D3-110 running at full load would be MUCH more durable and long lasting than the D3-220 running at full load. Sound about right?

Lets say I typically run at a rate that requires 100 HP. Which will be more durable and long lasting, the D3-110 running at 100 HP or the D3-220 running at 100 HP?
Click to expand...

Without more information, it is not possible to know whether the 110 and 220 have the same pistons, rods, crank, etc.

I have a pair of TAMD41s. One has been rebuilt, using a long block. My mechanic explained the numbers on the new block to mean that it has the same pistons, rods, etc as the TAMD43, but will never be called upon to put out the higher hp of the 43, because it has the old injectors, head, etc from the 41. To my uneducated ear, that tells me you don't know what differences there are in pistons, rods, etc between the D3-110 and 220 without more information.

Without that extra information, any statements made about durability are just WAGs.
 
Pascoe's numbers are probably not that far off if we only include pleasure boats (no fishing charters or anything). And include all of the many, many small, cheap boats that get very poor maintenance and have engines that die early deaths as a result. And all of the boats that do lots of sitting and might run 20 hours per year with correspondingly poor maintenance. It also includes speedboats and sport fishes that get run flat out a lot and wear their engines out quickly.

If you factor all of those situations out, the well maintained and reasonably operated examples (both gas and diesel) will run much longer.
 
I think I agree with this. When I first learned of the Ecoboost coming out and started working with engineers on the project, I really felt this was going to be a disaster in the making. " it will never live" I thought. I thought wrong, but every other gas turbo prior to that engine had dubious service life. I can't believe how long these motors are lasting. 420 pound feet of torque from a V6 is no small number. Technology and engineering are certainly advancing. Teflon coated pistons and diamond like coating on the wrist pins to name a few. They should add two holes to the front of the thing and offer an ecoboost V8 and marinize it! Bill


rslifkin said:
The anti-turbo thinking is pretty outdated IMO. Plenty of turbodiesels run for many thousands of hours (and with better efficiency than an NA diesel of equivalent hp).
Click to expand...
 
Again, comparing vehicle engines for land use to engines for a marine environment is an apple and orange argument. As you can appreciate my non-boating friends don't understand the load engines must endure as Pascoe points out. So I give them this analogy. Imagine a truck with a very long commercial trailer, loaded with potting soil for delivery, permanently going up a steep hill that never levels out. Well that motor will have a shorter life span than a diesel in the truck and commercial trailer on Interstates, mostly on the level all the time.
 
rsn48 said:
Again, comparing vehicle engines for land use to engines for a marine environment is an apple and orange argument. As you can appreciate my non-boating friends don't understand the load engines must endure as Pascoe points out. So I give them this analogy. Imagine a truck with a very long commercial trailer, loaded with potting soil for delivery, permanently going up a steep hill that never levels out. Well that motor will have a shorter life span than a diesel in the truck and commercial trailer on Interstates, mostly on the level all the time.
Click to expand...

In other words... for a boat continuously pushing through water... or... a truck hauling soil continuously pulling up hill:

To extend engine life - Have correct size power plant and gear ratio to begin with, and don't push the engine too hard regarding how fast you travel.
 
JLD said:
I find David Pascoe's articles interesting, but they are somewhat dated (the diesel one is 20 years old). Although I don't know enough to disprove the following, I am somewhat skeptical that:

"The average life expectancy of a marine diesel engine in a pleasurecraft is somewhere around 1500 hours between major overhauls. The average boat reaches this in about 8-10 years, meaning that the average annual operating time averages around 150 hours. If that seems unrealistically low, consider that that translates into 2-1/2 weeks of eight hour days. Most boats have years when its even less than that. If this surprises you, it may surprise you even more when I tell you that gas engines average around 900 hours before overhauls."

I would expect the numbers to be double of what he notes above, at least for well-maintained engines. Given how poorly many folks maintain their boats (at least mechanically) maybe his numbers are still valid after all this time?

And regarding boat size for diesels, it all depends on what the customer for the boat wants. Many Ranger Tugs owners seem quite happy with the diesel engine in their 21 foot boats!


Jim
Click to expand...
The problem with David Pascoe is that he was a surveyor with no grasp of scientific evaluation. Most of what he wrote about was based on his observations without regard overwhelming evidence to the contrary.

His other failing was being unable to distinguish product failure or life expectancy versus operator error.

Ted
 
rsn48 wrote;
“Using turbochargers is a no no according to David, and he is anti-aluminum; all for the same reason - heat.” The “David” would be David Pascoe.

I’m anti-aluminum too but for a different reason .. corrosion. When I repowered I made a point of not having seawater contacting aluminum. It dosn’t. I have a very durable exhaust manifold made of a special alloy that rusts .. but so slowly that after converting engines since the 60’s only one has needed replacement.
My seawater pump is a bronze Jabscoe.
The only thing aluminum on the engine is the valve cover.
 
Aluminum blocks and heads are fine, when designed appropriately. But I agree, no aluminum in the seawater side of the system. So no aluminum exhaust manifolds, pumps, coolers, etc.
 
Art said:
In other words... for a boat continuously pushing through water... or... a truck hauling soil continuously pulling up hill:

To extend engine life - Have correct size power plant and gear ratio to begin with, and don't push the engine too hard regarding how fast you travel.
Click to expand...

A power plant is generating horsepower. It doesn't matter if the vehicle is going uphill or downhill. Only difference will be that the vehicle will be traveling faster going downhill than uphill for the same horsepower.
 
Gas

rsn48 said:
It takes a lot of hours of run time to burn enough gas to reach the break-even point on the cost of a diesel engine. Most weekend warriors it is still cheaper to burn gas and repower a gas engine around 500-1000 hrs or 10 year intervals.

Some suggest you never really reach that break even point in cost between diesel, higher maintenance costs, more expensive parts and gas. Particularly for a person in their 70's, you just don't have the time to make the break even point. I will link a David Pascoe article below. Some react to David because he doesn't follow the company line, diesel is best all the time. In fact David suggests for boats roughly 34 feet and under you are probably better off with gas. My suggestion is before you read the article (in two parts), scroll down to the bottom to read his resume.

https://www.yachtsurvey.com/GasDiesel.htm

If you were a west coaster, I'd suggest you buy a new used boat or trailer your old one up here, purchase a condo on Whidbey Island and settle down in God's country. There a number of smaller towns you could live in or for a large metropolis (it is not), there is Oak Harbor. That way you could have a condo in a beautiful location and enjoy incredible boating destinations without the need for an air conditioner, nor screens on your windows, and you could handle the less than one week of snow a year, some years no snow. And you get to live in a rain shadow from the Olympic mountains, translation: significantly less rain and more sunshine.
Click to expand...

LOL. Nice to read your post. We lived in Oak Harbor for 4 years and it's a well kept secret. Great little town, great Marina with very reasonable prices, great cruising grounds. I wish I were back there.
 
ssobol said:
A power plant is generating horsepower. It doesn't matter if the vehicle is going uphill or downhill. Only difference will be that the vehicle will be traveling faster going downhill than uphill for the same horsepower.
Click to expand...

I beg to differ! :D

A truck engine at an rpm pulling heavy load uphill as compared to doing the same rpm with same heavy load going on the level or down hill is an extra stress on the truck engine while in the up hill mode. And, going down hill places the least stress on the engine. ;)

Pushing a boat through the water is not too much unlike a truck pulling a load uphill. :socool:

That's the way I see it! :dance:

Maybe a truck engine and boat engine engineer can chime in! I love to learn!!
 
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gas

djmarchand said:
Just had a long conversation with the service manager of a shop that repaired my friend's Volvo I/O powered 27' express cruiser. Most of the work on that boat was due to the I/O drive, not the engine and cost $4,000 this time. He had previously spent as much as $20,000 on a brand new I/O drive. A bit unusual due to a bad design by Volvo for that I/O.

According to the service manager the biggest service item on a modern EFI gasser is the riser and exhaust manifolds. These are apparently cast iron with very thin walls that corrode in about 5 years of salt water service and are considered a consumable item. Cost to replace is a couple of thousand dollars.

So gassers, particularly gassers wth I/O drives can also be expensive to maintain.

David
Click to expand...

If you own a gas I/O once, you will never own another one. It's the worst of both worlds. If you have one, I feel your pain.
 
trawler

JOY-SEA said:
Considering a different sytled boat
Trawler / type yacht
Present 2004 - 30 ft Regal Commodore beautiful well maintained
A Weekender, limited,
6 cylinder Volvo Penta , Gas , Kohler gen set

We like hanging at marina , talking with fellow boat owners , cruising,
fishing , sleeping aboard few nights returning back too home Orlando
We are retired 70 year old's .
Not ready too give up home
Beach Side Condo sounds nice but tied down ?????

HOW ABOUT A LARGER BOAT , lot cheaper then a condo, no HOA
Pack my bags leave few weeks , do a journey , go home

Surfing POP YACHTS , BOAT TRADER tons of boats
GB , Marine Trader Trawlers are nice , not sure if I would like that
type of boat long term

Mainship , Carver , Silverton type yachts offer a lot ,
Newer ones have nice styling , leather seating , luxury cabins ,
Wife would enjoy that
90 ies early 2000 within my budget

Sellers / Brokers advertise the perfect boat too cruise ,
GREAT LOOP ? Twin Mercruiser 350's - GAS ENGINES 2 Cruise ??

One broker advertised RARE - Carver with diesels ,

Generally go slow , sail boats pass me , still burn 1 gallon a mile ,
Don't want that in my next boat

Trawlers with diesels burn 2 -3 gals an hour

I see many regulars responding on this site with Mainships, Carvers,
Silverton type yachts .
Some thoughts , pros & cons certain years
What too look out for ? Best years
Got a nice one too sell or trade for my Regal
You get the gist

Thank U
Click to expand...

Ok, I'm parochial, but you are about the same age as me and you seem to do the same kind of boating that we do so I seriously recommend the Grand Banks 36 Classic. Two staterooms, two full heads, galley up. Look for one. You won't be disappointed.
 
Regarding the earlier posts about turbines; these were replaced by slow speed diesels (large commercial shipping) for reasons many have noted here. Chevron tried gas turbines on their tankers for the main power plant in the 80's, but it didn't last long if I remember correctly.
 
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But for offshore racers it can be a different story and why I said application of power is tantamount, not just low end torque.

Same with some warships.....
 
Pleas share what your alloy is?

Nomad Willy said:
rsn48 wrote;
“Using turbochargers is a no no according to David, and he is anti-aluminum; all for the same reason - heat.” The “David” would be David Pascoe.

I’m anti-aluminum too but for a different reason .. corrosion. When I repowered I made a point of not having seawater contacting aluminum. It dosn’t. I have a very durable exhaust manifold made of a special alloy that rusts .. but so slowly that after converting engines since the 60’s only one has needed replacement.
My seawater pump is a bronze Jabscoe.
The only thing aluminum on the engine is the valve cover.
Click to expand...
 
Portage_Bay said:
Pleas share what your alloy is?
Click to expand...

Please do share!

"I have a very durable exhaust manifold made of a special alloy that rusts .. but so slowly that after converting engines since the 60’s only one has needed replacement."
 
Portage Bay and Art,
I don’t know.
I can find out (I think) but they may consider it a trade secret now ???.
You could call them in Seattle. When I bought my engine the company was Klassen Engines in Seattle. But Klassen in Seattle was bought out by Hatton or Hatton Marine. A much bigger company. Klassen Engines is under the same roof as Hatton in Ballard .. Seattle. The parent company (Klassen Engines) is as before in the lower mainland British Columba Canada. They are in the city of Surry close to the border in NW Washington state. For info about the alloy it probably would be better to call Klassen in Canada than Hatton.

The alloy of the manifold starts with the letter M I believe and was a very well known in the 40’s and 50’s ... oh it came to me. Monnel. They use to make fuel tanks, propeller shafts, rudders and fasteners of this steel alloy Monel. It could be a brand name but Monel should lead you to what it really is.


But the manifold is not not actually Monel like all the other things but a close relative being alloyed by some or most of the metals in “Monel”. The manifold must be made from sheet or plate and almost certainly is still available. But the actual alloy information may need to come from Klassen. I’d recommend calling Klassen in Canada. I have only called Klassen in Canada once and that was about 13 years ago. All my dealings with the Klassen product lately has been through Yukon Engines at the Hatton company in Seattle.

Another memory flashback .. I think the marine engine company “MER” (also in Seattle) also had manifolds made with this same Monel-related material. Haven’t heard anything about them for some time either. If they still exist though it may be of interest to numerous TF members as MER made a specially engineered package for a JD engine (4cyl turbo) to be a drop-in type replacement for Ford Lehman powered boats. So MER (if they exist now) could be of help. It’s possible they even have or can get/make a Monel steel manifold for the FL. ??
 
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Once again leaving the FAR more important part of the equation out. The torque generated by the power plant is what allows the vehicle to maintain a higher speed up hill. The same torque used to pull a trawler through the water. For the purposes of moving a trawler one needs to be concerned with torque more than horsepower.






ssobol said:
A power plant is generating horsepower. It doesn't matter if the vehicle is going uphill or downhill. Only difference will be that the vehicle will be traveling faster going downhill than uphill for the same horsepower.
Click to expand...
 
Monel is used in staples as well. I have used them in most of my outdoor use soft goods. They still corrode, but much slower and with less weeping. Are you saying your
Manifold was was fabricated sheet steel manifold ? Cut and welded from sheet? Sounds pricey.






Nomad Willy said:
Portage Bay and Art,
I don’t know.
I can find out (I think) but they may consider it a trade secret now ???.
You could call them in Seattle. When I bought my engine the company was Klassen Engines in Seattle. But Klassen in Seattle was bought out by Hatton or Hatton Marine. A much bigger company. Klassen Engines is under the same roof as Hatton in Ballard .. Seattle. The parent company (Klassen Engines) is as before in the lower mainland British Columba Canada. They are in the city of Surry close to the border in NW Washington state. For info about the alloy it probably would be better to call Klassen in Canada than Hatton.

The alloy of the manifold starts with the letter M I believe and was a very well known in the 40’s and 50’s ... oh it came to me. Monnel. They use to make fuel tanks, propeller shafts, rudders and fasteners of this steel alloy Monel. It could be a brand name but Monel should lead you to what it really is.


But the manifold is not not actually Monel like all the other things but a close relative being alloyed by some or most of the metals in “Monel”. The manifold must be made from sheet or plate and almost certainly is still available. But the actual alloy information may need to come from Klassen. I’d recommend calling Klassen in Canada. I have only called Klassen in Canada once and that was about 13 years ago. All my dealings with the Klassen product lately has been through Yukon Engines at the Hatton company in Seattle.

Another memory flashback .. I think the marine engine company “MER” (also in Seattle) also had manifolds made with this same Monel-related material. Haven’t heard anything about them for some time either. If they still exist though it may be of interest to numerous TF members as MER made a specially engineered package for a JD engine (4cyl turbo) to be a drop-in type replacement for Ford Lehman powered boats. So MER (if they exist now) could be of help. It’s possible they even have or can get/make a Monel steel manifold for the FL. ??
Click to expand...
 
moparharn,
Haven’t looked at it closely for some time. But for sure the corners of the rectangular tube the main part of the manifold was made from has bent rounded corners .. not welded, perhaps one corner (bottom inbd.) was welded and I haven’t noticed. So I suppose it could have been made from sheet having numerous bends. Now I wanna run down to the boat and look.
Sure it’s pricy. With a engine like this you get real quality. But no shiny bright colored paint. Of course the manifold was part of the engine price but the price of the engine was a bit less than $6000 13yrs ago. $7000 w my extras like remote oil filter, remote belt driven seawater pump (bronze Jabsco) and some other details like oil extraction pump. A lot less money than comparable yacht engines. Klassen worked mostly w the fishing industry in BC and Alaska.
 
Nomad Willy,


Thank you. Yes indeed Monel is spendy. Klassen Seattle was a great shop to deal with. As was MER, I think MER is gone now. Hatton is a mixed bag. Some of my interactions with them have been great, some not so good. Hatton is a pretty big shop now, I think it depends upon who you get hooked up with there.
 
TY Eric - Should have known. I love Monel!!
 
Marine Manifold corp. here on Long Island NY has produced CuNi manifolds for quite some time with excellent results. We had a pair of them made for a twin diesel boat about 20 years back and they served us very well. They do need to be supported reasonably well and inspection over time is still a very prudent practice - there are failure points that occur over time and usage.
Marine manifold also works in many other materials dependent upon the application at hand.
 
Monel is pricey, but it's good stuff. After 33 years in salt water, the Monel strainer baskets in my old Groco SVS strainers still look pretty much new.
 
rslifkin said:
Personally, if I had to build an ideal gas boat engine, it would be something very durable but small displacement like a beefed up 4.8 liter LS motor or similar. And then add a turbo to get the desired power output with a wide powerband and without needing to rev it to the moon. If done right, it should be able to make easily the same power as a lot of the big blocks do with as good or better powerband and by virtue of being smaller displacement with boost, it should be noticeably more efficient at low power outputs than the big block would be (due to lower pumping losses).
Click to expand...

These type engines are taking over the outboard market for boats in the 40' to 60' range.
 
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