How about a 4bt Cummins? I didn't see it mentioned but it's lighter than the 6bt (just as durable too) and should be tunable to around 200hp.

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1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k

The guy on yachtsurvey is a biased idiot. He even admits that he thinks diesels are stinky and slow. He used to build "race engines" Yeah, okay Jerky, so did I but at least I have the facts straight. If engines aren't lasting in boats its because the owners are morons. Since both gas AND diesel engines don't seem to last and mostly because of lack of maintenence and care, whats that tell you? The engines are crap or the owners are idiots? Granted pushing any engine to higher horsepower MAY be detrimental to lifespan, IF you don't monitor the cooling and lubrication systems. There are plenty of marine engines out there that have 2000 and 3000+ hours on them without issue. Of course the engines in the shop are low-hour engines. They haven't been maintained! Duh! The ones that have are still running and you don't see them. The yacht club I frequent has plenty of high time engines happily doing their jobs. Diesels are expensive to maintain? I guess his marina must be charging and arm and a leg for oil changes and fuel filters..... RT

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When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K

MBZ automobile engines do not have the correct style of injection pump for marine applications. In order to function on a boat (or in a stationary power application too), these IPs need a speed governor that works over the entire RPM range of the engine, not just at idle-1000 RPM like the IPs on the 616, 617, 603 et al...

Operating a boat with an ungoverned diesel engine would be a gold-plated PITA...you would have to constantly adjust the throttle whenever operating at any speed other than dead slow.

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Never a dull moment at Berry Hill Farm.

Small diesel engines are generaly used in displacement hulls . In a planeing hull such as you Well Craft is I would think there would be very little GPH advantage over The Ford engine to justify the cost..........

William Rogers.........

Yes and no.

I had a 28' cruiser that had twin Mercruisers with about 225hp I think. At 20 knot cruise, I burned about 20 gph.

[ By the way, this boat had "exploded" after refueling by the the PO. Either forgot the blowers or didn't allow enough time. Blew out the windows, fried all the wiring and scared the crap out of a lot of people. It was the last time the owner stepped on the boat. I found out about this the day of our closing and almost backed out on the deal. But it was practically a new boat and the deal was pretty good. BUT, I always new this boat had a past, and not a pretty one.]

I have a friend with a 36' express cruiser with twin 454's that burns 35-40 gph at 17 knot cruise. He is hating life with marine fuel at $2.50 a gallon.

I currently have a 42' cruiser with twin Detroit Diesel 471's rated at 300hp each. I cruise 17 to 18 knots and with the generator on burn less than 20 gph. Back when fuel was $.70 per gallon, I could run around all summer for about $500.

Basically I burn 1/2 the fuel at 2/3 the cost per gallon as my friend to do the same trip. Not to mention that the diesel boat will hold its value much more than a gas boat will. Mine is still worth what I paid for it 7 years ago and his has depreciated another 40% in the same timeframe.

BTW, the boat is a 1981 Ocean Yacht with about 1600 hours on the Detroits and they have never been overhauled. Still very strong, but there are indeed some expensive maintenance issues. I just had a fuel cooler replaced to the tune of $800. Ouch! Even doing much of the work yourself, the oil and all filters will set you back a bit of change.

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Alan Hamm
'87 300SDL 277K Miles
'89 560 SL 68K Miles

There are lots of 4 and 5 cylinder Mercedes deisels used in sailboats. I recently saw a 46-foot Hinckley (top-o-the-line) with one. If they are marinized correctly, they are truly great. If my old Perkins ever gives out in my sailboat, I'm going Mercedes.

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1984 300Sd 210k

Former cars:
1984 300D 445k (!!) (Strider) Original (and not rebuilt) engine and transmission. Currently running on V80 ( 80% vegetable oil, 20% petroleum products). Actually not, taking a WVO break.
1993 300d 2.5 275k. Current 120/day commuter
1981 300SD 188k (Hans) Killed by a deer

My family had a 26' fiberglass trauler with a 4cyl NA Isuzu diesel engine in it. I remember looking up the specs on it (We had a couple of gas Isuzu Troopers at the time and I was dreaming of an engine swap) and it wasn't a high horsepower engine (~70hp). It pushed that boat just fine up to a max of around 15knots. I'd expect a marinized mercedes diesel would do just as good of a job, as long as you could find a way to properly get the power to the prop. The Mercedes engine has more torque and horsepower at the same RPM

I'm no expert but I don't remember reading about any bolt on transmission for a Mercedes diesel. That would be the first step for me. I'd be surprised if marinizing it would be a huge hassle.

You might find a better deal money wise with a used engine/transmission package.

Another resource is:
http://boatdiesel.com

-Tad

No doubt they are great engines for marine applications. They just need the correct fuel control system. It would be great to find out how MBZ designates the marine application engines used in those Hinckleys and what IP they use on them.

FWIW: MBZ Diesel Marinization Link

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Never a dull moment at Berry Hill Farm.

Why a 28 foot boat if it's used for water skiing
when there are boats much smaller and faster that should use less fuel? What kind of speed do you get with the 302 ?

I belive you will find that Mercedes marine engines are much more that just a car engine with a few mods. It sounds like a nightmare project to me and I can see no way that a 617 with it's 120 hp is going to be fast enough for skiing. I love diesel boats and though about getting a Grand Banks when I lived in Fl.........

William Rogers......

Thanks for all your replies! I'll try to answer a few more questions.

The boat currently is an inboard/outboard which I will be replacing with a bravo unit (I'm considering the Bravo III but I'm concerned with their corrosion problem).

The boat is used for a number of tasks, scuba diving, water skiing, fishing, and occassionally when weather permits, long distance expeditions.

Fuel range is a big problem, When traveling to some prime scuba diving spots, I have to carry an additional 100 gallons of unleaded in 55 gallon drums on deck to make the trip.

I was reading some articles about some diesel engines mercedes produced for prototpyes that were essentially modified 617 engines with larger injectors and bigger turbo, which put out 190 horspower.

As far as the swap goes, just about anything will fit in the engine compartment provided the engine isn't too tall of heavy (leaves out the cummins 5.9), there is no transmission to bolt up to, only a bell housing which appears to have been hacked from a chunk of aluminium.

I's like to limit the cost of the engine replacement to 5000 or less, as the new outdrive is going to cost me that!

Thanks for all your comments, I've definatly got some thinking to do.

Any outdrive will corrode if you leave the boat in salt water. I don't know what they cost and they might not be cheap, but the plastic Volvo outdrive is the best outdrive out their now. It is tougher than aluminum, is more efficient, and has a remote oil resivor. So at least you can catch the water in the oil before a bearing is wiped out. For five grand good luck, remember you will need new tanks, fuel lines, engine mounts, maybe new guages. Depending on the year of the boat the stringers may be getting soft, that could be a can of worms. If you went to a fuel injected 302 you would probably be doing better. It is a heavy boat for a single small block to push along.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

As a side note, one of the most versatile and durable engines is the legendary HINO 4WD and 6WD, these long lasting engines have been used as marine, commercial truck and bus as well as road roller applications and gensets. They are virtualy indestructible and last over 500,000Km with severe commercial abuse.

YANMAR...YANMAR...YANMAR

They take an inline (6) six Toyota block and add a 24 valve head
along with other "refinements" and end up with an engine
totally designed from the "crank" out for MARINE use.

Toyota Land Crusier inline (6) engine 204 H.P.
Same short block "YANMARIZED" 315 H.P.

Hint: watch any film of a parasail boat. It's powered by this
engine!

I think this is a very interesting thread.........

Williaqm Rogers........

After studying the schematics of the Bosch pump, I believe you are wrong about the govenor on the 617 pump. If you carefully follow the pump description at
:EDIT: removed bad link

you'll see that there is indeed a mild form of "governing" at mid throttle positions. They call it "torque control" and is described on page 10/7. The flyweight sleeve position still has a mechanical feedback loop to the control rod position.

Anyway, how would it be any different than his gasser 302 with a simple carb installed? The carb has no governing in that installation. I fail to see how it would so bad for cruising in a boat, but OK in a car driving down the level highway.