Diesel engine cost vs. gas
JASmith428
I was looking at a new 35 foot Tiara last fall. With twin gas 454's -
$239,000. With twin diesels similarly equipped - $298,000. Why so much
difference - really!! (not salesmen hype.)
IMQTPI
> jasmi...@aol.com (JASmith428) Asked:
Well, I'm no expert (Ha! Far from it!), but I can offer a
couple of anecdotes to the diesel vs. gas argument:
First, diesels are reputed to run forever. I *know* that they
are much simpler to maintain since I - bein' a girl and all -
am actually able to perform basic repairs and maintenance
on my Perkins T6.354 with little fear of screwing up.
Not much can go wrong with a diesel, from what I hear. If
you've got a problem, chances are it's because the engine
isn't getting air or fuel - both are relatively easy to fix (and
yes, I have had first-hand experience with this)...
Although, if something *major* does go wrong (and it
hasn't for me - yet <knock on fiberglass!> And there's over
2200 hrs on my engine) it's gonna cost a fortune...
Alternatively, gas engines *seem* (to me, anyways) to be a
lot more complex. I won't even tackle my Ford 302's -
it's more than my feeble little mind can comprehend ;-)
The other *plus* to diesels is in fuel economy. I'm sure that
someone will correct me if I'm wrong - but my neighbor,
who has a Chris Craft Coho 32 with twin 454's (I think!), and
I (aboard a big ole' honkin' Luhrs 32 S/F) made a similar trip
up to the Golden Gate bridge and back (don't ask me how
many miles). It cost him over $100 in fuel to make the trip,
and it only cost me about $13. Grant you, he did it *faster*
but he wasn't running at WOT - not by by a longshot...
One more positive for the diesel is in resale value. I can't
quote any facts or figures, but you will generally get more
for a diesel than gas...
I know that this is far from a scientific explanation - but I'm
pretty sure that *most* will agree that diesels are considered
better than gas. If I'm wrong, I'm not too worried - I can
handle the flames 'cuz diesel's not as explosive as gas
either! Heehee ;-)
QT***
m/v's Solitaire and Tartan
San Francisco Bay
Liveaboard advice at http://members.aol.com/imqtpi/private/qtboats.htm
Duane Clause
dollars for under 500 horsepower
CJ
>
> Can somebody "really" tell me why diesel engines cost so much more in a boat.
> I was looking at a new 35 foot Tiara last fall. With twin gas 454's -
> $239,000. With twin diesels similarly equipped - $298,000. Why so much
> difference - really!! (not salesmen hype.)
Assuming that you are talking about an approximate 350-400HP motor I
would say
that the difference of 60K is a rip-off. That price difference is
probably
negotiable, but you really need to consider a few things:
Engine Longevity:
A decent diesel engine should last you 10,000 hours, perhaps much more.
A
454 should give you between 1,000 and 2,000 hours of service.
Fuel Economy:
Figure around double the range with a diesel with an identical number of
gallons. My single screw 34' diesel gets 2.8 statute MPG at 38MPH. The
same hull with twin outboards would get about 1.2 MPG and a single screw
454 I/O should get about 1.5MPG.
Safety:
Diesel fuel takes a lot of heat to burn. Your insurance will be lower
and
you will have improved piece of mind.
Fuel Cost:
I can fuel my diesel for around 85 cents a gallon at the local dock, 93
octane gasoline at the same marina goes for around $1.65. Sooo, when
combined with the twice as good fuel mileage, you are talking about
a boat that is more than 4 times cheaper to run.
Resale:
Much better with a diesel.
On to the downside:
Diesels cost more; sometimes a *lot* more.
They omit some fairly nasty fumes when idling; often they make the
passengers sick when they are idling or trolling.
Not all marinas carry diesel.
My conclusion:
I bought a diesel boat primarily for the extra range. With 180 gallons
of fuel I can go about 500 miles comfortably. To go the same distance
with a twin outboard I would have to turn the boat into a floating fuel
barge. Since my primary use is extended offshore fishing, range
was the primary concern. If your primary boat usage is well within the
range of a gasoline powered vessel, then in my opinion, the extra costs
of a diesel are not worth it.
Just my $0.02, you can keep the change.
Clint
G. Schnauzer
Tiara 35"
The difference is essentially $60k. Say 20% profit for everybody that ever
touched the engines leaves $48k.
Take out the price difference for gas vs. diesel generator since that has to
change also - maybe also large kW Say $5k for generator leaves $43k. Two
engines = $21.5k each.
Factor in economy of scale. Number of 454 built probably measured in
hundreds of thousands per year. Number of diesels this model for Tiara and
everybody else probably less than 10,000. Basic overhead and manufacturing
costs will be much higher on the low production diesel.
Factor in heavy duty construction. The diesel is built to overall more
heavy duty specifications, therefore higher actual manufacturing costs.
Factor in all the add-ons to the basic engine such as headers, gearcases etc
are all low production & heavy duty = more expensive.
Factor in "marine application" which is always more expensive (cynical view)
no matter what it is.
Since no one else seemed to be actually answering the question I thought
this might start the ball rolling and perhaps someone who really knows will
jump in.
--
G. Schnauzer
JASmith428 <jasmi...@aol.com> wrote in message
news:19990114170322...@ng112.aol.com...
Gould 0738
more in a boat.
>
>I was looking at a new 35 foot Tiara last fall. With twin gas 454's -
>$239,000. With twin diesels similarly equipped - $298,000. Why so much
>difference - really!! (not salesmen hype.)
>
One of our local surveyors was once a mfg rep for a major diesel engine mfg.
Just like Schnauzer said; the diesel market is much smaller than the gasoline
automobile engine market (and most gas boat engines are
"marinized" versions of the same power plant found in the family station wagon)
so there is no economoy of scale.
Bringing us to *marine* diesels. How small is the marine diesel market in
relationship to the
overall diesel market? The company this local surveyor used to rep for used to
produce all of the diesels for their marine division on
*one* (!) production day per year.
This puts a lot of overhead costs (to maintain a presence in the marine diesel
market) onto the back of a small number of units being sold.
Jumbo costs apiece.
One of the major magazines did a study a few years ago comparing the costs of
owning a boat purchased new with diesel engines and
an identical boat purchased new with gas engines. They made some assumptions
about engine hours per year, etc; and projected that both boats would be sold
in x years (the diesel reselling for more than the gas). If my aging memory
serves me well, I seem to recall that after several years of use and eventual
resell, the diesel was no more expensive than the gasoline engines.
The longer you plan to keep your boat, the more sense diesel makes. If you are
looking at the 35 foot Tiara as an interim boat until your Amazon.com stock
splits enough more times that you can afford a Feadship (next year?), the
cheaper engines might be a better choice.
K Smith
I guess I agree with the other answers, resale value, safety,
reliability, fuel consumption/cost, maintenance costs, service life etc.
but there are some real reasons for the extra initial cost like;
(i) The average diesel say Cummins 320HP or Cat, is built to much
higher tolerances than the average Chevy. This applies to nearly every
component.
(ii) Even some similar looking components are in reality very different
say;
(a) Valves, high quality running on top quality valve seat
inserts vs average quality running directly in the cast iron head which may
or maynot have some induction hardening.
(b) Pistons, Forged high quality with at least 4 sets of rings
& sometimes inserts vs maybe cast & three rings.
(c) Connecting rods/gudgeon pins, high cost alloy forgings
running large bearing surfaces, & well retained pins vs cast rods with
press fit/retained pins.
(d) Crankshafts, forged steel sometimes with seperate balance
weights vs an iron casting.
(e) Cam drives, properly engineered/lubricated gear drive
systems vs a chain on sometimes placky sprockets.
(f) Lubrication, very high capacity pressure system, with spray
nozzles that keep a continuous jet of oil cooling the underside of the
piston with every section of the engine directly fed vs a modest system
with no piston cooling & relying on "splash" lubrication for many minor
components.
(g) Oil temp control, nearly all diesel have either a builtin
oil cooler or an external system, always thermostatically controlled so the
oil gets up to temp quickly but doesn't go over vs no oil coolers just
reliance on a too low operating temp.
(h) Diesel injection systems, pumps, lines, injectors, filters
etc are all precision equipment but fed clean fuel, will last many
thousands of hours vs spark plugs, distributors/caps, coils, leads, carbs
etc which are cheap but will need regular replacement with the labour costs
on top of the parts costs.
(j) General construction, very robust with lots of webs cast
in, many head bolts/studs per cylinder, nearly always replacable cylinder
liners/sleeves vs mostly light duty construction where the addition of
extra main bearing bolts is a cause for joy.
(k) Turbos, diesel engines of the type being discussed are
usually turbo (super) charged & sometimes also intercooled being very
expensive again precision & long lasting equipment vs run at normal
manifold pressures
(iii) Considering what you get in a modern diesel I say they're very good
value when you consider what you get, compared to the average say Merc.
Volvo/Chev. or particularly an outboard. (the new DFI OB engines make a
properly engineered diesel with a proper gearbox, low, cheap fuel
consumption, long life (at least 10 times) etc. etc. look really good
value) The Merc. Volvo/Chev engines can be upgraded & indeed they are by
Merc. themselves with special blocks, forged steel cranks, brand name
forged rods/pins, special high performance pistons, cyl. heads with good
valves & seat inserts, even upgraded lubrication with oil cooling, but by
then they cost heaps more than the diesel & will last even less time.
Karen.
K Smith
I forgot the closed, long lasting, corrosion free, proper operating temp.
coolant fluid cooling system with a proper heat exchanger vs raw maybe salt
water cooling which allows the engine to operated a too low a temp &
corrode very quickly.
Karen
BSteveMHSA
a domestic vehicle is about $6000 when buying an equivalent diesel for a
pick-up or similar. While some of the price of the diesel is used up in terms
of marinization, there doesn't seem to be any justification for the huge
difference involved here. (Other than the fact it says marine on it of course)
Rod McInnis
Gould 0738 wrote:
>
> Bringing us to *marine* diesels.
So just what is a "marine* diesel?
I know what a marine gas engine involves. Starter, alternator, and
distributor need the spark supression/flame shields. Fuel pumps need
dual diaphragm/controlled vents. Carburetor needs special float bowl
vents. Since a great many engines are used in a raw water cooling
system, the head gasket and "freeze" plugs are often different. Often
different camshafts are used.
How about the diesel? Since the fuel used is safer, do they have the
same requirments for flame suppresion on the electrical components?
Since they would tend to be used in larger boats, where fresh water
cooling is more standard, would they have different head gaskets?
I wouldn't expect there to me much difference between a marine diesel
and a standard diesel. Can somebody enlighten me?
Rod McInnis
K Smith
I think you're right, apart from the marinisation items,
(manifolds, h/exchangers, oil/trans coolers, marine intercoolers, marine
turbo housings etc.) there isn't much different in the engine itself.
Varies, but sometimes the electrics, (starter & alternator) are
"different" in that the housings are above ground (i.e. they have a
seperate earth lead. This is more for proper isolation than spark
suppression like petrol engines.
Karen.
Larry
>Can somebody "really" tell me why diesel engines cost so much more in a boat.
>I was looking at a new 35 foot Tiara last fall. With twin gas 454's -
>$239,000. With twin diesels similarly equipped - $298,000. Why so much
>difference - really!! (not salesmen hype.)
HEAVY PARTS! Diesels, with their 21:1 compression ratios, require much
heavier bearings, rods, heads, gaskets, cranks, etc. than gas engines.
There is more power, as the diesel injection CONTINUES to provide
power after the piston starts down. Injection systems are far more
complex than fuel squirters (gas "injection") or carbs. Precise
high-pressure metering of fuel oil is a science in itself.
Larry...Ahh, the smell of diesel fumes as we leave the dock!
We're now in heaven!