Gas vs. Diesel

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Properly used and well maintained quiet/odorless/vibration-free gas engines seldom experience any real big internal problems. Oil pump here, burnt valve there, timng chain maybe... but, mostly items such as those relatively minor ones do not occur. Gas engines can and often do seamlessly last into the 4k hour range, or over. Replacement is relatively low cost (about 1/4th to 1/5th diesel). Easy to work on (do maintenance to) during years of increased-pleasure boating!
 
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I've met Richard in Alaska and clearly is an excellent source of advice or/and information. Going 6 knots most of the time I can't see why he dosn't get a FD boat over twice the size of his boat now and have three times the space on board .. w no increase in fuel burn. I may have asked him that and he probably told me it's where he lives and the trailer advantage. Probably work related too. He's not old like me.

Hi Eric,

Can't use work as the excuse - been retired 17 years now (that's how I'm able to spend the summers on the water). I do like being able to keep the boat in dry Utah air when not cruising, however, and occasionally to poke around on Lake Powell.

But after 24 years cruising in trailer boats, I am at last getting serious about switching to a more comfortable cruiser that doesn't cost tremendously more to operate.

Likely candidate is a 37 Nordic Tug - looked at a couple of nice ones in the Anacortes area on the way back home this year. Seems I might be able to cruise for similar $$/nm, since nmpg would be not too much worse, and I wouldn't have to spend a small fortune on truck diesel towing up to Prince Rupert. And I sure could accommodate 1-3 crew members better. I'd have to figure out how to rig her for fishing. Exciting new project?
 
OK good Richard,
I'm GaGa over the NT 32 and if I was familar w them I'd prolly be GaGa over the 37. I think it's mostly the wheelhouse that win's me over on the Nordy's.
Where would you keep the boat then? You always use Rupert to launch .. Yes? I hope some day you'll come through W WA.

A dream boat for me could be a NT 32 w a 4cyl Cummins w Aqua Drive.
 
Hi Eric,

Have launched in PR the last ten years, but have done Bellingham several times for BC cruises, and a full Inside Passage trip from Everett to Glacier Bay and back once.

I do like my buddies' NT32, but there's more to drool over on the 37:

The 37 has a second stateroom. I don't have to go down steep narrow steps from cockpit to salon deck - they're the same level. The salon roof/boat deck is big enough for a nice dinghy. Some even have electric cranes.

It would probably be in Anacortes or thereabouts. Where's Willy?
 
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Just to go back to the OP's question - I think the real answer is: It depends.

I have a real outlier - a 76 43' Viking Double Cabin - identical hull to their sportfisherman - just infilled the SF cockpit to make a stateroom. Power is twin 454 Crusaders rated at 350 hb - carbeurated with electronic ignition. The Hobbs show about 1650 hours. I have no objective history on the engines other than knowing through serial numbers that the blocks and heads are time commensurate with the build date for the boat. Original? Repowered with correct vintage remans? Rebuilt in place? Dunno.

Viking produced a couple of hundred over the period of 76 to 83 (?) or so. They were optioned with either the Crusaders or 6-71s. Talking to the Viking guys over the years (including Paul, who project managed the DCs but has since retired) it seems they were about 50/50 diesel/gas. But no hard records.

I do know that the old girl will still make the Viking advertised numbers for speed (27 K) and that the oil analysis results for the past 4 years is good and stable. Compression is good all holes.

Normal operation is either in "trawler" mode at about 8.5 - 9 K (2200 rpm, 8 gph by Floquips) or (if I'm feeling flush that day) a planing sweet spot of 13.5 - 14.0 K (3200rpm).

Am I worried about the safety factor of gas? Yes, to the extent that I take precautions, have systems that help to manage that risk, and conduct preventative maintenance - just like I did/do with aircraft that I flew, other smaller boats, cars that I drive, and the myriad generators, power washers, lawn mowers that I own. I'm by no means a wrench-head, but upkeep is pretty straightforward with basic handtools.

I'm pretty much a day cruiser, with occasional expeditions to the barrier islands off AL and MS or a run to the Florida panhandle. She's good for 150-200 miles with reasonable reserves. Fuel economy? In my experience, and doing maybe 200-250 hours underway per year, the cost of fuel is one of the less expensive items in boat ownership.

When I bought her (yes I had her surveyed by an old established surveyor who knows old boats), everything was sound - but not pretty. I talked to a lot of guys who operate 454 powered work boats (lafitte skiffs, mostly - working small operation fisherman) who swear by the big block Crusaders. last a long time, easy to maintain, relatively inexpensive to replace/rebuild when compared to a lot of diesels. Decided that, net out, for that boat and my intended use - she worked. And never looked back.

If I were one of you guys in the PNW who runs up to Alaska now and then, I'd have never considered her. If I had believed everything I read about the 35' or 40' "cutoff" for gassers I wouldn't have bought her. But for my deal, the gas power works out perfectly. I don't have a shred of diesel envy.
 
Normal operation is either in "trawler" mode at about 8.5 - 9 K (2200 rpm, 8 gph by Floquips) or (if I'm feeling flush that day) a planing sweet spot of 13.5 - 14.0 K (3200rpm).

No kidding, 8 gph @ ~10mph? That doesn't sound nearly as bad as I thought. . .especially when I read some gph quotes for the GS 44 I was looking at (~5gph @ 10 mph) and a MainShip 40 DC with twin Detroits (6gph @ ~10mph).

8gph gas vs 5 gph diesel over 100 hrs use is ~$1100 difference in fuel bill (~$2900 vs ~$1800) using local marina prices. . .and this is assuming you'd actually travel a 1000 miles a year total! I'm a working guy with other outdoor interests, so if I even was able to put 1/2 that a season on a boat I'd think I died and went to heaven :angel:

Here's a question I'm really interested in: For those of you with gassers vs diesels (both twins). . .what is your average maintenance costs per 100 hrs? ie, how much more expensive is diesels vs the fuel savings?

Here's another I don't think has come up in this thread: Has anyone noticed a steady price difference for the same make of boat gas vs diesel? Me personally, I've seen MS40's have about a $20k price premium for diesel (that buys a lot of gas). I'm not sure if that's because a diesel MS40 is rare, though.

For average expected useage, at least for me (and probably most people), gas wins hands down. So my third question: Why can't I psychologically wrap my head around the idea of buying a boat with a pair of Big Blocks?
 
Maintenance of my diesels after 100 hours is an oil and filter change. I also change the heat exchanger zinc on one engine. The other engine has a monel heat exchanger = no zinc. I just serviced the injectors on one engine after 1,100 hours = $120.
 
Just to go back to the OP's question - I think the real answer is: It depends.

I have a real outlier - a 76 43' Viking Double Cabin - identical hull to their sportfisherman - just infilled the SF cockpit to make a stateroom. Power is twin 454 Crusaders rated at 350 hb - carbeurated with electronic ignition. The Hobbs show about 1650 hours. I have no objective history on the engines other than knowing through serial numbers that the blocks and heads are time commensurate with the build date for the boat. Original? Repowered with correct vintage remans? Rebuilt in place? Dunno.

Viking produced a couple of hundred over the period of 76 to 83 (?) or so. They were optioned with either the Crusaders or 6-71s. Talking to the Viking guys over the years (including Paul, who project managed the DCs but has since retired) it seems they were about 50/50 diesel/gas. But no hard records.

I do know that the old girl will still make the Viking advertised numbers for speed (27 K) and that the oil analysis results for the past 4 years is good and stable. Compression is good all holes.

Normal operation is either in "trawler" mode at about 8.5 - 9 K (2200 rpm, 8 gph by Floquips) or (if I'm feeling flush that day) a planing sweet spot of 13.5 - 14.0 K (3200rpm).

Am I worried about the safety factor of gas? Yes, to the extent that I take precautions, have systems that help to manage that risk, and conduct preventative maintenance - just like I did/do with aircraft that I flew, other smaller boats, cars that I drive, and the myriad generators, power washers, lawn mowers that I own. I'm by no means a wrench-head, but upkeep is pretty straightforward with basic handtools.

I'm pretty much a day cruiser, with occasional expeditions to the barrier islands off AL and MS or a run to the Florida panhandle. She's good for 150-200 miles with reasonable reserves. Fuel economy? In my experience, and doing maybe 200-250 hours underway per year, the cost of fuel is one of the less expensive items in boat ownership.

When I bought her (yes I had her surveyed by an old established surveyor who knows old boats), everything was sound - but not pretty. I talked to a lot of guys who operate 454 powered work boats (lafitte skiffs, mostly - working small operation fisherman) who swear by the big block Crusaders. last a long time, easy to maintain, relatively inexpensive to replace/rebuild when compared to a lot of diesels. Decided that, net out, for that boat and my intended use - she worked. And never looked back.

If I were one of you guys in the PNW who runs up to Alaska now and then, I'd have never considered her. If I had believed everything I read about the 35' or 40' "cutoff" for gassers I wouldn't have bought her. But for my deal, the gas power works out perfectly. I don't have a shred of diesel envy.

I saw a few of that engine on the lake, in ski boats. As an interesting point on Crusader engines, Correct Craft, the builder of Nautique, purchased PCM and Crusader engines last fall. Crusader had an excellent reputation on ski boats, although generally smaller than the 454.

I agree with your "it depends."
 
Has anyone noticed a steady price difference for the same make of boat gas vs diesel? Me personally, I've seen MS40's have about a $20k price premium for diesel (that buys a lot of gas). I'm not sure if that's because a diesel MS40 is rare, though.

Yes, I've noticed a price differential as there is new and used. I think it's greater percentage wise on used boats, but that's because of the perception that diesels have a longer life. They do, but that may not come into play, just as it hasn't for you.
 
That'd be a Floscan - not sure what a floquip is.

Either gas or diesel fuel consumption is going to increase geometrically with speed. However, I have a hunch the curve is steeper for gas. When I did the 27 knot runs I didn't have the Floscans, but I imagine fuel burn approximated a DC-3's.
 
It's not so much a "differential" as a discount for gas. I think used gassers (mid 30 to 40s) in the boat brokerage business are viewed pretty much like a used car dealer sees a full size 6 cylinder pickup - something he's got to sell because he's in the business. They "set" the prices to move it.

As BandB stated, gassers will inevitably be cheaper, all other factors being equal.
 
A question, not an opinion or claim......

I wonder if back in the heyday of the whole production diesel cabin cruiser thing, which I suppose might be said to have gotten kicked off by American Marine and their Grand Banks series so in the mid-1960s, were there gas engines that would have done eqally as well in that "Dependable Diesel Cruiser" role (to steal American Marine's slogan for the Grand Banks line)?

There were a whole raft of automotive/industrial/agricultural diesels from the likes of Ford of England, Perkins, and so forth and they had a fairly proven record of longevity, reliability, and efficiency plus the diesel safety factor.

But were the gas engines of the day equally up to that particular cruising boat job?

I have a friend whose farther bought a new Richardson 28' cabin cruiser in the mid-50s. My friend and his brother still own and occasionally use the boat today (it lives on Seattle's Lake Union). Power is a pair of Graymarine (I think) raw water cooled gas engines. The range of this boat is quite low and the engines seem to need a fair amount of tweaking and tuning to keep them running correctly, although how much of this is due to age and infrequent use and how much to the fact these engines were like this I don't know.

I know gas was the power plant of choice in the cruisers made during that same time frame by Chris Craft and other similar makes.

But specifically in the slow, heavy, economical, relatively long range world of the production cruisers like GB, CHB, etc., did diesels get their foothold simply because they offered a better propulsion solution in that era than the available gasoline engines?
 
Just to go back to the OP's question - I think the real answer is: It depends.

I have a real outlier - a 76 43' Viking Double Cabin - identical hull to their sportfisherman - just infilled the SF cockpit to make a stateroom. Power is twin 454 Crusaders rated at 350 hb - carbeurated with electronic ignition. The Hobbs show about 1650 hours. I have no objective history on the engines other than knowing through serial numbers that the blocks and heads are time commensurate with the build date for the boat. Original? Repowered with correct vintage remans? Rebuilt in place? Dunno.

Viking produced a couple of hundred over the period of 76 to 83 (?) or so. They were optioned with either the Crusaders or 6-71s. Talking to the Viking guys over the years (including Paul, who project managed the DCs but has since retired) it seems they were about 50/50 diesel/gas. But no hard records.

I do know that the old girl will still make the Viking advertised numbers for speed (27 K) and that the oil analysis results for the past 4 years is good and stable. Compression is good all holes.

Normal operation is either in "trawler" mode at about 8.5 - 9 K (2200 rpm, 8 gph by Floquips) or (if I'm feeling flush that day) a planing sweet spot of 13.5 - 14.0 K (3200rpm).

Am I worried about the safety factor of gas? Yes, to the extent that I take precautions, have systems that help to manage that risk, and conduct preventative maintenance - just like I did/do with aircraft that I flew, other smaller boats, cars that I drive, and the myriad generators, power washers, lawn mowers that I own. I'm by no means a wrench-head, but upkeep is pretty straightforward with basic handtools.

I'm pretty much a day cruiser, with occasional expeditions to the barrier islands off AL and MS or a run to the Florida panhandle. She's good for 150-200 miles with reasonable reserves. Fuel economy? In my experience, and doing maybe 200-250 hours underway per year, the cost of fuel is one of the less expensive items in boat ownership.

When I bought her (yes I had her surveyed by an old established surveyor who knows old boats), everything was sound - but not pretty. I talked to a lot of guys who operate 454 powered work boats (lafitte skiffs, mostly - working small operation fisherman) who swear by the big block Crusaders. last a long time, easy to maintain, relatively inexpensive to replace/rebuild when compared to a lot of diesels. Decided that, net out, for that boat and my intended use - she worked. And never looked back.

If I were one of you guys in the PNW who runs up to Alaska now and then, I'd have never considered her. If I had believed everything I read about the 35' or 40' "cutoff" for gassers I wouldn't have bought her. But for my deal, the gas power works out perfectly. I don't have a shred of diesel envy.

Bravo!
 
Here's a question I'm really interested in:..... Why can't I psychologically wrap my head around the idea of buying a boat with a pair of Big Blocks?
Probably because you are afraid, one day, they might go BANG.
 
Probably because you are afraid, one day, they might go BANG.

Or perhaps he's just not after speed. My last two lake boats were a 25' Bowrider with 2x310 hp and a 30' Bowrider with 2x430 hp. On the lake there were a lot of boats in the 50 mph and up speed range and big block engines were quite common. Mercruiser 8.2 engines and their various options were very popular engines. Single engines for 25' and under, twins for larger.

Oh and we put heavy hours on them and no BANG. Now we did maintain them well and also used them reasonably, going through the proper break in and then never running them more than 5-10 minutes at a time at WOT, varying speed regularly, and using only original equipment parts and manufacturer recommended fluids.

Almost all the ski boats and wake boats had big engines and they held up well in spite of being subjected to a lot.

Now, not to bring up another hot discussion taking place recently as it was on diesel, not gas, but many of these builders of stern drives and inboard gas engines have gone to pretty large displacement vs. hp. That allows RPM to be kept in a reasonable range which I do think helps with a gas engine. You're talking in the engines we had 430 hp out of 500 cubic inches so RPM maxed at 5,000.
 
"But were the gas engines of the day equally up to that particular cruising boat job?"

For trawler crawler speeds there were loads of engines. If you only need 30-60 hp at the shaft the old Chrysler were a smooth 6 cylinders .Palmer was another choice.

Even with the early mfg , metalurgy and assembly methods many would run 2,000 hours or about 7 years till the sea water cooled units rusted thru.

Sadly in that era only about 10 hp per gal was the norm, today with a modern gas 14 is not hard to do.

Even so 4gph was a dollar an hour of fuel cost.

The biggest problem with gas today is the difficulty of finding non ethanol fuel while on the cruise.
 
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To be clear, according to BoatUS gas outnumbers diesel by about 30 to 1 (or higher) for all boats sold. Once above 15,000 lbs diesels dominate. Many 35 to 45 foot boats made in the 70s had big block Chryslers or Crusaders, me being one. The diesel choices for boats made in that era focused on the very big and heavy 6-71, not a good choice for us weekenders back then.

Today's gas engines on the drawing board rival diesels for economy and will be a game changer in cars. BUT lots of electronics and very high CR required. Diesels have been problematic in maintaining emissions standards as they age in land based applications vs gas. As Euro standards tighten for smaller diesels, great new engines are springing forth.

Fun times abound in the engine arena that will hopefully move into the boating sector, whether gas or diesel.
 
But Tom,
Great new gas engines are comming at perhaps an even faster rate. I personally think diesels in cars will be a thing of the past eventially .. or sooner.
My gas Honda Accord gets well over 30 mpg average .. Probably closer to 35. It's a 33 - 3400lb sedan .. not an economy box. Just a hair smaller than my old Buick LeSabre. Fourteen gallons took us to Portland and back plus some at 535 miles. I can't believe anybody would need better millage. Why pay a lot more money for a diesel?

Marin,
Re your post #162 I think the older (50s & 60s) gas engines were very dependable if maintained and used regularly. Sound familar? Breaker points spark plugs and carbs needed regular servicing. Now that spark plugs last 100K miles in a car (I had one that did that w a carb) and gas engines are fuel injected the gas engines are not to be rejected for dependability. FF's point about alchol in the fuel is a good point though. I can't believe that still happens. Do they have ethanol gas in Europe?
 
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"My gas Honda Accord gets well over 30 mpg average .. Probably closer to 35. It's a 33 - 3400lb sedan .. not an economy box. Just a hair smaller than my old Buick LeSabre. Fourteen gallons took us to Portland and back plus some at 535 miles. I can't believe anybody would need better millage. Why pay a lot more money for a diesel?"


I have 2 of those Honda engines as well - but you ask a good question at the end.
"Why pay a lot more money for a diesel?"


Here is my reason - when I need to haul a lot of weight and/or load the engine up due to towing or snow the best choice is a diesel.
 
"but many of these builders of stern drives and inboard gas engines have gone to pretty large displacement vs. hp. That allows RPM to be kept in a reasonable range which I do think helps with a gas engine"


An observation which I would agree with in both terrestrial and marine applications. Once you start to add hp and FI to any engine the ratios begin to tell you how well the engine will last. At least in my experiences with adding hp to any engine.
 
I even had a two stroke OB in the mid 70's go from Juneau to Seattle without missing a beat. Was a late 60's Jhonson 3cyl 55hp engine on a 12 knot boat. This engine had three sets of breaker points.

Avoiding maintance is a favorite American bad habit. Forty to 50 years ago a favorite slogan to sell lots and lots of products is to present them as "maintance free". With the exception of water in the fuel the diesel engine was much better at running on w/o much maintance and got popular mostly for that reason I suspect.

Another thing to take note of is that earliest trawlers, then called heavy cruisers were mostly powered w gas engines. A typical boat was a strip planked, Monk designed "bridgedeck cruiser" w twin flathead 6cyl gas engines. I could be wrong about the number of, or percentage of gas and diesels but I'm quite sure at least in the 50's gas was more popular. Of course there was always a size point where most became diesels.
 
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"My gas Honda Accord gets well over 30 mpg average .. Probably closer to 35. It's a 33 - 3400lb sedan .. not an economy box. Just a hair smaller than my old Buick LeSabre. Fourteen gallons took us to Portland and back plus some at 535 miles. I can't believe anybody would need better millage. Why pay a lot more money for a diesel?"


I have 2 of those Honda engines as well - but you ask a good question at the end.
"Why pay a lot more money for a diesel?"


Here is my reason - when I need to haul a lot of weight and/or load the engine up due to towing or snow the best choice is a diesel.


I agree,
Even in the 50's lots of heavy equipment was diesel fot that reason. Single rear axel vehicles like school busses, vans and service vehicles were gas almost universally in the 50's. Dump trucks and other heavy duty vehicles hauling heavy loads on the highway more or less continously were diesels even then. Don't remember seeing a gas cement truck even though they were/are considered intermittent duty vehicles.

PS the Honda I spoke of is a 2013 w cvt transmission.

PS Diesel stern drive installations in small low aspect ratio boats are at a disadvantage because or the extra weight of the diesel engine.
 
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I have had the pleasure to work on a few of those old flathead six marine engines. Chryslers. Raw water cooled, engine turned around backwards with flywheel on the front. Tranny mechanical and shared engine oil sump. Based on car engine blocks around 250cid. The marinization was pretty well done. And engines seemed to last reasonably long even with raw water cooling. A few are still alive, but most of these had most of their lives in fresh water. The salt water ones are long gone.

Those engines did require a little tweaking of the carb to run right, but once dialed in that was a very sweet running engine!!! Nothing seems as smooootttthhh as a straight six. And you can idle them down to like 400rpm and not stall. And quiet. About 100-150hp.

Those were the go-to engines from the 40's into the 60's, then replaced by the overhead valve v8's. Diesels did not really show up in numbers until the early 70's oil shock. Lehman was a pioneer then.
 
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Normal operation is either in "trawler" mode at about 8.5 - 9 K (2200 rpm, 8 gph by Floquips) or (if I'm feeling flush that day) a planing sweet spot of 13.5 - 14.0 K (3200rpm).

Before I got too excited, I forgot to ask if that was a single engine or combined?



And no, I'm not afraid of "BANG". Never had anything but gas powered boats my whole life. Current sailboat is a '75 powered by an Atomic 4. Was raw water cooled until i rebuilt it earlier this year, now freshwater cooled. Runs like a top! Managed to avoid exploding these last 40 years :thumb:

I've actually had people tell me I'm going to die living on a gas powered boat. With the way people talk about gassers and how dangerous they are, I'd expect at least monthly fires at the local marinas. Nearly everything is gas powered out here. . .
 
The only downside to gas is it's eagerness to burn or explode so if one can get around that why would anyone want a diesel engine w it's propensity to vibrate, stink, make lots of noise, cost lots of money and be excessively heavy?
:thumb: I know that there are many on this forum who have gassers & it is not my intention to debate their choice but in an attempt to clearly explain my position on gas engines, I offer the following.....
 

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Yeah, that's it Codg.

Cool beans - that's aggregate - about 4 per side. That's based on the Floscan needles. I'm not sufficiently disciplined to make a sustained run @ say 8k, and compare the totalizer to the pump refuel numbers. Always seem to wind up with some relaxed planing speed in the mix. I use 1 nmpg for "trawler" leg planning and it's never too far off.

As to BANG - BoatUS stats attribute 95% of fuel fire claims to gasoline. Fuel fire claims are 8% of their total boat fire claims. 92% other - electrical and engine overheats predominate. Given my experience in getting quotes from BoatUS for my boat and talking to them, they are way more oriented to smaller craft than boats of the size we deal with here. In any case, the standard of "recognize the risk and manage it accordingly" applies.
 
Craig wrote;
"That Honda is not going uphill constantly either."
Of course not. Nor was I recomending anyone should put one in a boat either. I mention it as an example of gas engines becoming quite to very efficient now. Have no idea if it would take a 50 to 65% load continuously. I suppose it could be the major part of a 160hp OB though.
Awhile back I could tell when a guy started his Crusader FI gas V8 in a 26' Tolly ... I could tell because it ran so perfect.

Walt are you saying you have a strong opinion in #176?
 
Re: FF # 166 - Not a comprehensive survey by any stretch, but I'm not aware of any fuel dock between Galveston and Pensacola that doesn't pump non-polluted (non-ethanol) gasoline. That may be due to our locale - proximate to a bunch of refineries. No boat owner I know (jon boats to go-fasts and everything in between) would allow ethanol fuel in their tanks.
 
Re: FF # 166 - Not a comprehensive survey by any stretch, but I'm not aware of any fuel dock between Galveston and Pensacola that doesn't pump non-polluted (non-ethanol) gasoline. That may be due to our locale - proximate to a bunch of refineries. No boat owner I know (jon boats to go-fasts and everything in between) would allow ethanol fuel in their tanks.

It's that way where we live too, but we recently looked as a result of people here saying it and we found there are many areas of the country it is very hard to find non-ethanol gas.
 
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