Gas engines / verses Diesel on larger boats ??

[JOY-SEA]

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

 

[Baker]

I think too many people get hung up on trawler "style" boats. You can do the same thing with a Carver(as an example) that you can do with a "trawler". I would say the advantage is you get a LOT more boat for the money. Look in your 90s/2000 range and you will see the 440 and 445. Diesel power. A TREMENDOUS amount of space. And they can be had for a small amount of money. Another advantage is if you do want to giddyup and go, you have that option at the expense of fuel of course. I will also say that a boat like a Carver is significantly better engineered than the vast majority of "trawlers"....not to mention detailed schematics of onboard systems. My owner's manual is damn near as detailed as the airplane manuals I deal with. Oh also a full parts list...right down to the window screens and curtains. Yeah the important stuff is on there but I mention those as an example of how detailed they are. And Carver is still in business. So a phone call is an option when you are trying to track down parts.

SO there are advantages to mainstream mass produced boats. They just may not look like trawlers. But there is no reason you can't use them in the same manner.

 

[DavidM]

Well, your post is a little hard to follow. I think you are asking whether it would make sense to sell your Regal 30' gasser and buy a larger diesel powered trawler that you can use for longer cruises.

The diesel trawler will use less fuel, about 1/3 less at displacement speeds and much, much less comparing going fast in the Regal vs going slow in the diesel trawler. Is that important? It all depends on how much you cruise and how fast you want to go.

Does it make sense to buy a larger, probably more expensive trawler with increased maintenance, insurance and dockage costs vs a home or condo? Well the house or condo will appreciate but the trawler will depreciate and the maintenance and operating costs will be higher for the trawler. But it will probably cost much, much more for a water front condo or house and will require HOA or condo association fees.

It all depends on what you want to do and how much you want to spend. We made the choice to buy a canal front condo and downsize to a small outboard powered boat.

David

 

[Shrew]

IMHO all boats are a compromised in something. Trawlers are tend to be slower, but can travel further, longer and more cost effectively. The protected side-decks on all sides are great for safety underway and when docking, but you loose usable cabin space in the process. Trawler tend to have more tankage. I also find them more stable at anchor or mooring.

If you're intention is the social lifestyle of dock life, with occassional overnights and a few weeks here and there, then ANY boat will allow you to achieve your goal. In fact, an Aft Cabin Silverton or Carver will give you the most livable space at the most affordable cost+space per foot.

Diesels are only needed for extended duty cycle and fuel economy. A 39 Silverton AFt Cabin with Gas 496 (8.1L) or 502 (8.2L) are fine for most dock, weekend, vacation use. 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.

 

[Ken E.]

Joy, Have you considered just keeping your existing boat for the purposes you list? It's in nice shape, good for marina stays, would probably do the Loop for you. You'd save a lot of money that could be used on fuel or other things.

 

[rsn48]

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.

 

[boatruptcy]

I'll take diesel maintenance all day every day over gas motor maintenance. That's a total myth that diesels cost more, maybe (and I stress maybe) if you look at the life of the engine over several thousand hours assuming your gassers don't implode in that time, you could argue it costs more, specifically if you are swapping injectors, aftercoolers and turbos. Otherwise, good fuel filters, oil change and valve lash as required is about it (some require aftercooler service). Compare that to plugs, plug wires, cap, rotor, nearly every season and then carb rebuilds etc.

 

[ranger58sb]

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

One broker advertised RARE - Carver with diesels ,

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

Lots of those brand boats -- including Carver -- with diesels; not particularly rare at all.

Driving many of those at "trawler" speeds can be reasonably economical, if the up front cost for diesels fits within your use case and within your budget.

Start with listing features you need/want/would like to have... then find boats to match... without regard to brand (at least at first) or whether it has "trawler" in the name.

-Chris

 

[BDofMSP]

I also have a 30' Regal Commodore (2765 model name but 29'10" LOA). Mine has an 8.1 L Volvo gasser. The boat only has a 78 gallon tank, which means about less than 70 gallons of useable fuel with any reserve to speak of. If you're doing any cruising on plane, that's not enough tankage for some areas of the loop.

Perhaps you have a different model with larger tanks?

 

[FF]

SO there are advantages to mainstream mass produced boats. They just may not look like trawlers. But there is no reason you can't use them in the same manner.

The biggest advantage is they build maybe 20 - 100 times as many boats per year so get great owner feedback. This creates the far better interior layouts and use of space.

Unless you are one of the rare folks that cruise something like the loop many times ot snowbird 1500 miles up and 1500 miles back fuel costs will not be a problem , unless you choose to go really rapidly.

A modern gas engine will last 3000-4000 hours with few parts like $5.00 spark plugs.

See what $5.00 gets at the diesel shop

Diesel Folks probably spend more per year on new fuel filters than a gasser does on annual maint..

With huge hours per year or limited fuel volume diesel does make more sense.

 

[DavidM]

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

 

[smitty477]

"SO there are advantages to mainstream mass produced boats. They just may not look like trawlers. But there is no reason you can't use them in the same manner."

The biggest advantage is they build maybe 20 - 100 times as many boats per year so get great owner feedback. This creates the far better interior layouts and use of space.

Unless you are one of the rare folks that cruise something like the loop many times ot snowbird 1500 miles up and 1500 miles back fuel costs will not be a problem , unless you choose to go really rapidly.

A modern gas engine will last 3000-4000 hours with few parts like $5.00 spark plugs.

See what $5.00 gets at the diesel shop

Diesel Folks probably spend more per year on new fuel filters than a gasser does on annual maint..

With huge hours per year or limited fuel volume diesel does make more sense.

The rest of the post makes sense but....
"Diesel Folks probably spend more per year on new fuel filters than a gasser does on annual maint.."
Our typical diesel fuel filters cost was about $75 for two mains and a genset over about 1,200 miles per season.

 

[rslifkin]

Normal maintenance for my 454 gassers is pretty much:

• Pencil zincs, spark plugs, oil, oil filter, and trans fluid every year, around $100 per engine
• Raw water impeller, distributor cap and rotor every 2 - 3 years
• Exhaust risers every 5-ish years, manifolds every 3-ish sets of risers (manifolds are fresh water cooled so they last longer). Risers are around $400 per engine with gaskets, etc. Manifolds cost around $600 per engine with gaskets, etc.

Beyond that, it's stuff like spark plug wires, belts, hoses, oil coolers, etc. on an as-needed basis, most of which isn't much different on gas vs diesel. In 33 years, 1 engine has had a carb rebuilt once, the other has had it twice. Generator carb has never been removed. My engines are electronic ignition, so the ignition systems pretty much "just work" although the points ignition on the generator requires occasional attention.

For the most part, the engines just work without being problematic or requiring attention beyond normal planned maintenance and checks. My only complaints are the rate at which they drink fuel and having to carry a lot of highly flammable fuel around for them. One engine was replaced before the boat was mine (currently has around 100 hours on it) due to a failed oil cooler line (and slightly inattentive operator) leading to spun main bearings. The other engine has about 1500 hours on it, still running just fine.

 

[psneeld]

Had probably 5000 hours on the 454 gasser in the assistance tow boat I ran for 12 years full time and another 2 part time.


Obviously saw less than ideal operating life and maintenance than most recreational boaters.


Only had plugs changed once when I was operating her, a few other issues. Injection elbows until the head mechanic found a stainless part that lasted way longer.


I believe the short interval for risers and elbows are for saltwater cooled I/Os which are different animals for the most part. Inboards, fresh water cooled with flush systems can go longer....the trick is to look for water in the oil every day and don't run it. You can change out early and probably go 7 years between and if you do it yourself the parts and DIY labor aren't too bad....it's the labor that's expensive.

 

[Solly]

You already have a boat so you know what you want to do and some idea what you need to do it. Best advice... Go look at boats. Any make, model that comes close to what you think you might want.

Very generally a less than 30' boat will have a 10' beam. Over 30' and it goes up to 12'. That 2' difference makes a whole lot more space available.

My very humble opinion is that a 34' to 36' boat is ideal for a couple until you want to liveaboard. We use our 34' Mainship the same way you do and it's pretty much all we want. Easy to handle, good amount of room, and fairly economical.

1 bedroom, waterfront apartment, with a view that changes !

Good luck !!

 

[Codger2]

I think too many people get hung up on trawler "style" boats....... there are advantages to mainstream mass produced boats. They just may not look like trawlers. But there is no reason you can't use them in the same manner.

(Whew) Thanks for that, John! I've felt like that for quite awhile!

 

[RCook]

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

Pascoe's article is misleading, particularly regarding his comments about the average life span of diesels. He does not mention that the average diesel is not well taken care of.

My 26-foot cruiser had a 260hp Volvo KAD44P, one of the lightweight diesels he dislikes. I put 6,502 hours on it in the 18 years I owned it, and it was still in good shape. No expensive repairs, no need to get inside the engine, in all that time. (The stern drive was not as good a story)

My current cruiser is 18 years old. Its Cummins 6BTA 5.9 M3 had 1489 hours when I bought it, and I've put 3100 hours on it in the four years since. No expensive repairs or maintenance on it either. Regular maintenance, done by me, has been oil and filter changes, zincs, raw water pump impellers, one serpentine belt, and checking/cleaning sea strainers, transmission oil cooler, heat exchanger and aftercooler.

A properly set up, operated, and maintained diesel should last many thousands of hours. If that is desirable, or if the fuel economy and therefore additional range on a tank is desirable, a diesel can do the job. IF you take care of it.

 

[Shrew]

Marine Gas Engine's lasting 5000 hrs is an extreme, not the norm. Like all things, you can point to a few examples, but that makes it an exception rather than a rule.

It may be anecdotal, but I find gas big blocks over 1,500 hours is more of an exception than a rule. look at the average number of hours on a repowered big block gas engine and it is nowhere near 4,000 hrs.

 

[rslifkin]

Marine Gas Engine's lasting 5000 hrs is an extreme, not the norm. Like all things, you can point to a few examples, but that makes it an exception rather than a rule.

It may be anecdotal, but I find gas big blocks over 1,500 hours is more of an exception than a rule. look at the average number of hours on a repowered big block gas engine and it is nowhere near 4,000 hrs.

I'd be curious to see the cause for repowering next to the number of hours. I'd be shocked if most of the causes weren't due to something killing an engine (often neglect induced like water intrusion due to failed risers) or due to someone just being scared of the number of hours on it.

As an example, my dock neighbor has a Formula with a pair of 496HOs in it. At the end of the season he was just shy of the 1000 hour mark on them, so he decided to get them rebuilt this winter just in case, even though they were running perfectly fine.

 

[fgarriso]

Joy

You didn't state the number of people you plan to cruise with, or how far you plan to cruise.

If you want to go with 2 couples then you would be looking at a 40+ or larger boat to have two state rooms and a 50' boat to have two heads with showers. Even a 60' boat will not have the room of a 2 bdr condo.

How far to you want to travel per day, per week, per month.
Most trawler boats at displacement speeds will run at 7-8 knots. With that speed you would be looking at 50 miles per day on the average.

Fuel cost per gallon is less with diesel than gas ( 3.00-D 4.00-G gal ) average for most places. Maintenance for gas or diesel is similar if you plan to do it your self. If you tale it to a boat yard then ask the service manager what they charge for annual maintenance on each type of engine.

You need to be realistic on how you plan to use the boat and then buy the boat that fits you needs.

I know this does not answer your questions, but you need to answer them you self.

 

[psneeld]

Marine Gas Engine's lasting 5000 hrs is an extreme, not the norm. Like all things, you can point to a few examples, but that makes it an exception rather than a rule.

It may be anecdotal, but I find gas big blocks over 1,500 hours is more of an exception than a rule. look at the average number of hours on a repowered big block gas engine and it is nowhere near 4,000 hrs.

I would say that is because they die of lack of use...not from actual running hours.


The fleet of tow boats I worked on (7 boats)...I can't remember but maybe one big block that didn't last around 3000 hours an that was because of water ingestion I believe.


The average engine ran 500 hours a year and lasted 5-6 years....most were changed out more likely for convenience due to a busy season.




And these engines mostly saw service that a rec boater would never do to their engines.


Yes, I know most gas engine changeouts are on lower hour motors...but my guess is not because the block is worn out...just like diesels...it's other issues.

 

[rsn48]

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.

I just had my very old Merc and drive yanked out and a new 2019 Merc 6.2 L 350 hp installed. The engine is fresh water cooled to prevent corrosion as discussed in above posts about salt water cooled engines. My old Merc (really a chevy) was salt water cooled and as stated by David Pascoe corrosion is an enemy of marine engines. I'm not surprised the gasser that lived for 5000 hours enjoyed such an extreme longevity. Its continual use prevented corrosion.

My expense for the engine and leg - Bravo 2 - was roughly $30,000 Canadian. The Bravo 2 was something under $3000. There is no history for the new non-automotive engine Mercuries, so I'll be curious as to how it fairs. What I am hoping for is that Mercury went out of their way to solve some of the problems when using a automobile engine so my fingers are crossed for a good long engine life.

 

[rslifkin]

The Merc 6.2 liter isn't automotive based? I thought it was just a re-tuned and marinized variant of the GM 6.2 liter LS engine (which is a very solid engine already).

IMO, it doesn't matter if an engine started out as an automotive engine or not, what matters most is how well it was marinized and whether it's durable enough for its intended power output and usage. It would be nice if gas marine engine manufacturers were better about publishing a max continuous RPM and hp output for good lifespan, as spec-ing that to be at or above the boat's cruise power requirement matters more than peak HP.

 

[Art]

The biggest advantage is they build maybe 20 - 100 times as many boats per year so get great owner feedback. This creates the far better interior layouts and use of space.

Unless you are one of the rare folks that cruise something like the loop many times ot snowbird 1500 miles up and 1500 miles back fuel costs will not be a problem , unless you choose to go really rapidly.

A modern gas engine will last 3000-4000 hours with few parts like $5.00 spark plugs.

See what $5.00 gets at the diesel shop

Diesel Folks probably spend more per year on new fuel filters than a gasser does on annual maint..

With huge hours per year or limited fuel volume diesel does make more sense.

What he said!

 

[Art]

A properly set up, operated, and maintained diesel should last many thousands of hours. If that is desirable, or if the fuel economy and therefore additional range on a tank is desirable, a diesel can do the job. IF you take care of it.

True! Can pretty much say the same for a good gas engine longevity; that is if it's well cared for and used often but gently.

 

[Art]

You already have a boat so you know what you want to do and some idea what you need to do it. Best advice... Go look at boats. Any make, model that comes close to what you think you might want.

Very generally a less than 30' boat will have a 10' beam. Over 30' and it goes up to 12'. That 2' difference makes a whole lot more space available.

My very humble opinion is that a 34' to 36' boat is ideal for a couple until you want to liveaboard. We use our 34' Mainship the same way you do and it's pretty much all we want. Easy to handle, good amount of room, and fairly economical.

1 bedroom, waterfront apartment, with a view that changes !

Good luck !!

What he said!

PS: Tri cabin 34 to 40 foot boats provide a lot of interior comfort with big sun deck sitting surface well above water surface. Although... that layout does pretty much negate cockpit area for hands on reaching over the side or transom to tend to items. On 34' you need to be on big swim step or have a 40'er with small cockpit.

 

[sbu22]

SO there are advantages to mainstream mass produced boats. They just may not look like trawlers. But there is no reason you can't use them in the same manner.

Spot on, Baker. My Viking is based on their 43' sportfisher - with the cockpit decked over and a bit of added saloon length. definitely not a "trawler". I bought it to live aboard as a bachelor. In my judgement, it would serve nicely as a couples live aboard if you were so inclined. With a 14.5' beam, minimum 7' overhead clearance, two full heads, etc. and a very open floorplan, it's relatively spacious and open. Close but sufficiently comfortable for the two annual annual week or so Gulf "cruises" with 4 adults and 2 grandchildren. Viking sold about 200 of this model between 1976 and 1984, with about an even split between 454 and 6-71 powerplants.

The mains are two Crusader 454s @ 350 hp. These are old school carbureted engines with after market electronic ignition. otherwise stock. At what we refer to as "trawler speed" (6.5 to 8 kts) the 454s burn 6-8 gph (total) by Floscan. Say 1600-2000 rpm. This is our typical underway speed. At 13-14 kts on plane, a nice sweet spot for the boat if you want to get somewhere, the fuel consumption goes to 30-32 gph (both sdies total). At 25-27 kts (WOT), I just don't look - burns gas like a DC-3.

The 454s have about 1,700 hours on them with good oil pressure, compression, and good oil analysis (checked at every 100-150 hr oil change). The only major engine work has been the precautionary replacement of the exhaust risers when I bought it 8 years ago. It is probably significant that this was a fresh water boat until I bought it. Now it lives in brackish water the majority of the time, with occasional trips into real salt water.

As I recall (haven't read the article recently), Pascoe thinks a 43' is too much boat for gas engines. I've not encountered a situation, including some pretty rough and sustained weather, where I felt compromised by lack of power.

I wouldn't hesitate, were I so inclined, to do the Loop in the old girl. With my usage, the cost of fuel in the context of boat ownership is nearly incidental. And, as a septugenarian, liefe-cycle cost calculations of gas vs diesel become harder and harder - the numbers just don't work out.

Buy a boat you like (you gotta "like" it - there are a lot of good boats out there that I just don't like) that's in good shape and suits your needs - don't get hung up on style, brand, or fuel.

 

[LaBomba]

We went from a 33 ft trawler to a 37 gasser and although we burn a little more fuel $ I wouldn't go back. The room and creature comforts far outweigh the benefits of having diesels for us. We also travel at trawler speed, 7 to 8 knots and our 454s are relatively efficient at that speed and about 1500 rpm. These engines should have a long life at that rpm. You have to like the boat, that should be the primary consideration

 

[Nomad Willy]

LaBomba,
Gas engines become closer to diesels in efficiency at or near full throttle. Never heard of gas engines being efficient at low bell.

But those engines of yours should be very smooth and quiet at most any speed. A gas engine would work wonderfully in our boat requiring only 18hp for a cruise speed of 6 knots. Only 2 and 3 cylinder engines exist around 30hp. And at selling time I’d probably come up w far less than I’d like.

 

[rslifkin]

Gas engines become closer to diesels in efficiency at or near full throttle. Never heard of gas engines being efficient at low bell.

Agreed. Plodding along at 6.5 - 7 kts I can only manage somewhere around 1.2 - 1.3 nmpg with twin 454s. At 17 - 18 kts it's more like 0.5 - 0.6 nmpg. A modern pair of diesels would get the same hull to about 3 nmpg at the lower speed, 0.9 - 1 at higher speed. So about a 40% improvement for high speed, but easily 60% at lower speed.

Of course, at low speed the gassers are nice and quiet (especially up on the bridge) even with my boat not having a lot of sound insulation on the engine room. On plane, it's a different story with plenty of intake howl and other general engine noise (exhausts are still fairly quiet though). But it was pretty cool running through some of the fast sections of the Erie Canal up on plane and realizing I could hear the engine intake noise escaping through the hull sides and vents and echoing back off the banks of the canal.