Educate me on diesels

[Bottom Line]

I boat on on inland lake. I have read volumes(on CSR and SRO) of info on the efficiency and advantages of diesel engines. Most, if not all, of the new 40DA and 44DA ordered by the local dealer, have gas engines. Of course the 44DB and 48DA will have diesel, since there are no other options. I have talked to several owners of larger boats, and they don't like diesel. I guy on my dock just bought a '04 380DA. I asked him he looked at a '97 450DA that is for sale at our marina? He indicated that he would not own a diesel because because he was tied up next the this 450DA last year and he had black soot on the side of his boat after they untied and the diesel smell with the genny running was awful. I am not trying to get a gas vs. diesel debate started. Is there a strong diesel smell when runnng the genny? Do the engines smoke alot? There are a lot of very knowlegable diesel owners on this site...so please educate me.

 

[fwebster]

Some people have a "thing" about diesel smells. If you do, then pony up and enjoy spending the $4/gal for gasoline.

For most people, however, this is a very minor adjustment in their boating career and the trade offs greatly off set the little adjustment period you go thru.

As long as you are considering a diesel made after about 1994-5, soot shouldn't be a problem. The engines are very clean buring and the only time you will get any smoke at all is immedieately upon start up if the engine is cold, which is a characteristic of all diesels. Soot on a transom is one of the indicators you learn to watch for. If you see soot on the boat, then something is usually wrong with the prop pitch, the bottom condition, or mechanically with the engine. I've got a 450DA and the only time I see any accumulation at all is when the bottom is dirty and I run at close to cruise rpms. On a 35 degree day, I get about 5 seconds of "cold engine smoke" then none at all.

All diesel engines consume a lot of intake air.......it has to go somewhere once it has burned with the fuel, so the volume of the exhaust is significantly greater than with a gas boat. In other words, there is just more exhaust with a diesel. On the rare occacions when you are anchored with the generator exhaust on the up-wind side of the boat and the wind is very light, you may notice the generator ehaust smell..but you would with a gasoline generator too. The difference, however, is that the diesel generator expells much less CO than the gas one.

One more thing about smells......raw unburned diesel fuel has a distinctive odor that most people don't like. If your engines are adequately maintained, you should never smell raw fuel. In fact, the presence of raw fuel odor is a danger signal telling you to go look at your engines and fuel system to find the source because you have a leak.

You asked some specific questions and I hope I've answered them. If we need to debate the gas vs. diesel thing again, I'm up for it, but the only objections to diesel power in a 40+ ft Sea Ray that are valid boil down to the fact the the initial cost of the boat is higher and some boaters are not willing to adapt to the smells.

 

[Alex D]

You should see my slip neighbor with his 1990 420DA with 375hp Cat 3208s in there ... when he leaves we have San Francisco style fog all over the marina .. :lol: those engines were just recently fully tuned (pump settings and injector clean and test) up by Cat after he had a head gasket fail and they still smoke like hell ... good engines though ...

 

[fwebster]

All I can say is your neighbor isn't done yet. The 3208 is an older design but your description is not what one should expect from 3208's.

 

[Alex D]

All I can say is your neighbor isn't done yet. The 3208 is an older design but your description is not what one should expect from 3208's.

Yeah, in the early 90s I used to drive Ford Louisville tandem trucks on the farm with naturally aspirated 3208s with 220 hp. It's the blue smoke on cold start that he's got and that is quite obnoxious ... I remember that from the farm trucks too.

My neighbor with the 38AC with 3116s does not have that smoke, but man do those exhausts throw soot and water against my hull when he fires her up and let's her idle for 10 minutes. The water literally shoots a good four feet striaght out of the side exhausts. I always have to wash my port side after he leaves.

 

[Bottom Line]

Frank...thank you for the info on diesels. I have become interested in diesels from reading all of the posts. What is extremely interesting is that you guys with 42-45 boats with diesels have about the same fuel burn as my 300DA does with gas. I have never driven or riden on a diesel powered boat (except a cruise ship)...but you mention getting diesel engines to a lake boater...and they kind of turn their nose up at you. About the only diesel powered boats on our lake are in the 45+ range...where gas engines are not even an option. I envy you guys on the coasts where diesel is much cheaper than gas...on our lake it is only 30-40 cents cheaper that gas...not much of a difference. Frank....thanks again for your education.

 

[osd9]

........ where diesel is much cheaper than gas...on our lake it is only 30-40 cents cheaper that gas...not much of a difference. ..........

Not so lately.....here in NJ, where gas prices have been going down, the price of diesel has stayed the same.

I just went with a neighbor on Monday to fuel his 38DA with Gas. At the local marina....regular gas (87 octane) was $3.02 and Diesel was $2.77...that's only $0.25 less for the diesel. And on the roads....regular gas.... $2.39...... and diesel.... $2.65.

About a month ago that wasn't the case...Diesel was typically $0.75 to $1.00 less per gallon than gas.

 

[Asureyez]

Why Diesel

I believe diesel power is a safer design for marine use. Less explosive opportunity and will deliver more BHP to the prop. Heavier boats need "Power to the Prop!"

As for smelly exhaust ... cold diesels in mechanical engines can't burn off the fuel because the block is cold and rob compression heat and diesels run on heat, and they like it hot. Older naturally aspirated engines without air heaters will smoke badly until they warm up. Newer designs are much much better. I have 2001 build Cummins Turbo mechanical engines and they will smoke very lightly on start up and once hot ... nothing. After an 8 hour run there will be little or no soot on the transom except immediately around the exhaust bypass outlet.

Newer electronic diesels are amazing in their lack of exhaust particulate.

I know many boaters on inland lakes don't consider diesel power due to higher purchase cost and low availability of fuel. So I suspect one has to consider the cruising ground in this decision.

Then there is resale to consider ... a 40 foot anything in gas power will have a market on the lake its in ... try to get it sold on coasts ... another issue.

I know a gas powered 40 SR in So Fla is a problem to sell at all to the local market. But a diesel 40 on Lake Lanier in Ga might suffer a similar fate.

I won't tell you that new diesels are less complicated than gas because with the new electronic engines, that isn't so. The newones take a electronic tech to tune them just like gas power today.

 

[Alex D]

........ where diesel is much cheaper than gas...on our lake it is only 30-40 cents cheaper that gas...not much of a difference. ..........

Not so lately.....here in NJ, where gas prices have been going down, the price of diesel has stayed the same.

I just went with a neighbor on Monday to fuel his 38DA with Gas. At the local marina....regular gas (87 octane) was $3.02 and Diesel was $2.77...that's only $0.25 less for the diesel. And on the roads....regular gas.... $2.39...... and diesel.... $2.65.

About a month ago that wasn't the case...Diesel was typically $0.75 to $1.00 less per gallon than gas.

True here too ... gas at the marina is now $3.02 for regular and 3.10 for 93 Octane. No diesel on the lake.

 

[Bottom Line]

True here too ... gas at the marina is now $3.02 for regular and 3.10 for 93 Octane. No diesel on the lake.

Alex...if there is not any diesel on the lake, where do the diesel guys get their fuel?

 

[Alex D]

True here too ... gas at the marina is now $3.02 for regular and 3.10 for 93 Octane. No diesel on the lake.

Alex...if there is not any diesel on the lake, where do the diesel guys get their fuel?

The marina has a diesel truck from a distributor come in and fuel them ...

 

[Four Suns]

I'll throw a couple of my thoughts out here.

If your boating is confined to a 10 mile lake and there is no diesel fuel on it, then obviously a diesel boat doesn't make sense. I will add that I would even question if a 40+ foot Sea Ray (diesel or not) makes sense. If I was going to put a boat that big on a lake, I think I would look at some of the nicer houseboats (and I'm not joking) and put some water toys on it... it would be cheaper and more fun on the lake.

The other thing, that Chad talked about, you have to be concerned about is what the sphere of buyers/sellers are in these bigger boats. Having a gas bigger boat limits the probable buyers to the lake and not the coasts or bigger rivers. Taking long cruises (5+ hours per day) in a gas 38+ foot boat is just not practical due to range and engine design. When I talked to the sales guy here about the 36DB with diesels, he said the gas version had a very short range (less than 150 miles) and was not practical on the coast here. However, less than a 150 mile range on a 10 mile lake is fine.

As far as the smoke... well... Diesel technology is advancing (or has advanced) to the point that is just not an issue. My Onan 4 cylinder diesel generator runs at a low 1800 RPM, makes very little noise in the sound box, has no turbo, puts out no smoke, and will probably outlive me. I had the raw water hose plug up on it last weekend and it still didn't smoke/smell and I had my hand right over the exhaust port on the hull wondering where the water was. Gas generators (marine use or not) are noisy, smelly, and dangerous and just not meant to run for 96 hours straight at cruise and on the hook (I've done it). I don't know anyone in their right mind that would leave a gas generator running overnight at anchor in any Sea Ray. That's like trying to beat a train at the crossing: "You might make it... you might not... but the consequences are really bad". But hey... "look at all the money I saved by buying gas and TURN OFF THAT LIGHT, TURN OFF THE AC, AND CLOSE THE COOLER BECAUSE WE CAN'T RUN THE GENERATOR!" However, I do run my diesel generator through the night. Also, I'm not sure of the life span of these low-rpm diesel gennys are but I bet it's on the order of 20,000 hours.

As far as smoke on my big diesels, it's just not there but I have 2003 vintage diesels with the electronics. I've never cleaned soot off the back of my boat even after running for 12 hours. I have seen it on others but the newer diesels just don't do that anymore unless something is very wrong. I do have small amounts of white steam that come out the back under cruise but it's a trail of about 6 to 12 inches.

My 2 cents. And I've owned gas in a 380 Sundancer.

 

[Alex D]

The Gary-man is right on. Our lake is about 40 miles long and has 500 miles of shoreline. We never travel more than 40-50 miles a weekend. The market for express cruisers is strong as people cannot afford houses on the lake anymore ... prices have gone through the stratosphere in the past six years ... and are using boats to spend the weekend or the entire week and their vacations. Big boats sell fast on the lake ...everyone starts in the twenties and moves up to fourty plus footers within two to three years. We have several 500 dancers on the lake and numerous 38 and 42 ACs, tons of 340 dancers and a good amount of 380/410 Dancers. Our marina has over 50 34 foot and up Sea Rays and there are 13 marinas on the lake. There are two sail boat marinas with up to 40 foot sail boats too. SO big boats make sense on SML. Big gassers sell well for exactly the reasons the G-man mentioned and you can get more boat for less money, while not killing yourself with the fuel cost. It's a limited, local market that however expands to be significant if you consider it is relevant for of the hundreds of inland lakes (except the Great Lakes) in the US.

Big gassers do sell reasonably well ... just not on the coast ...

 

[jrirvine1]

I’m in the “Need to be Educated†camp regarding diesels and have just started to look at the pros and cons of the oil burners for our next purchase. Hey, it’s never too soon to plan and scope out the next boat. Right now, I’m thinking a 40 – 42 foot dancer with diesels, rather than a boat in the mid 30’ range with gassers.

A few weeks ago, at the marina, I was discussing engines with a retired coast guard diesel mechanic and found he had an unexpected and different perspective. He claims that the diesel only makes economic sense depending on how much you use the boat and how far you travel. If you spend perhaps an additional 20K or so for the diesels, but only travel an hour or two away from your home port once a month, then you will likely never realize the savings on fuel during the time you own the boat. This assumes of course that many of us only keep our vessels a few years before moving on.

An interesting argument and one that makes almost absolute sense, if there is such a thing. If you don’t plan on using the diesel for what it was designed for, then why pay the extra cost, as 20K can purchase a lot of gas for a few years.

 

[never monday]

Jim,
There are other factors to consider also. Maintainance cost are less with diesel, insurance is less, and with fuel on sale it makes more sense to me.

 

[ImpulseIII]

Jim. One of the biggest advantages to diesel engines in a larger boat is the value of that boat at resale time. You will recapture most of the additional cost associated with a diesel purchase.

All the other "benefits" of diesel ownership then become gravy.......

 

[Bottom Line]

If I was going to put a boat that big on a lake, I think I would look at some of the nicer houseboats (and I'm not joking) and put some water toys on it... it would be cheaper and more fun on the lake.

Gary...interesting you mention this...because houseboats have become very popular on Table Rock the last few years. They have huge living spaces...just like a house. Here are a few pics on a brand new one forsale on Table Rock Lake. A lot of the houseboats rarely leave the dock...especially when there is some wind, because they are so hard to dock in the wind. I just can't quite make the houseboat jump....I am only 42...maybe I need to be over 60 to enjoy a top speed of 7mph. This houseboat is about 18 X 85.

 

[Skip]

My only add to Gary's comments is that I do get a bit of smoke on cold start with my 2003 C series Cummins. This goes away after 15-30 seconds. I also get a little smoke when I come on plane after an extended run in a no wake zone, but it is neglible and not a nuisance. As to the effect of the smoke on the hull, no residue on the transom, no residue on the swim platofrm, but I do get a 12" diameter circle of light gray residue around my exhausts. I can live with all of that.

regards
Skip

 

[jrirvine1]

The next boat will be diesel. The mechanic dude was just trying to be helpful, as he also owns an oilburner.
I slip my boat on a nice bulkhead that we call Searay alley. We have a 44 Sedan bridge, 46, 410, 340, 300 and a 420 (sundancers). All have diesels except the 340 and my 300. None smoke much except the older 1990 420 on my starboard side. When he lights up, I need to go ashore until he is gone and the smoke clears the area.

I like the 2001 410. We sometimes run together for raftups and there is something about the lines of this boat that to me look “just right†while it is on plane and running at about 25 knots. What do you think Frank? Nice boat or what?

 

[ImpulseIII]

Nah........I really like the lines of a Bayliner better.. :grin: