Diesel Outboards....

[oscar]

They are out there, but mostly not in the USA from what I can see. Does anyone know of diesel outboards being sold in the US with adequate support structure?

 

[Paul in Saudi]

I have oft wondered the same thing. I have never seen a diesel outboard anywhere. I suppose it is a pollution thing.


No having to carry two fuels would be a good idea.

 

[Ski in NC]

I think there are three in the mill right now, none US based or much supported:

OXE: Euro car based engine somewhere around 150-200hp

Cox: Prototyping a big v8 around 300hp. Been a few seen in the flesh, but not sure if in production. I think based in the UK. Big thing!

Neander: Very interesting two crankshaft two cylinder around 50hp. Their design solve much of the infernal two cylinder vibration issues. I think this was sold to Yanmar who apparently put it in production. Never seen one stateside in the flesh, probably more focused on the international market.


Diesel outboards probably won't sell well in the States for several reasons. They will be expensive. They will be loud. They will be heavy for the power they make. Also, with direct salt water cooling the corrosion gives them about the same 15-odd year service life gassers have before corrosion does them in.

And fuel prices stateside (for now) are pretty low, with diesel actually commanding about a $0.50 premium over gasoline (at least on the road, where most outboards fuel)

I can see an advantage in commercial apps like small ferry tenders to mooring fields, crabbers, clammers, etc... But with such limited acceptance in the market, support will likely remain sketchy. If I needed OB for commercial use I would not be the first guinea pig. Stick with well proven, popular and well supported gassers. Even if the fuel cost ends up a bit higher.

Apparently in some areas (Euro, etc) due to taxation and fuel prices, they make enough sense to support their development.

 

[Nomad Willy]

Diesel engines were not on pleasure boats 60-70 years ago because they were just too heavy. Then there was the expense and the stinky and the noise and the vibration ect ect. One should ask how they ever made it into pleasure boat engine compartments.

Then there was outboards. And they became heavier rather than lighter because of the 4 stroke thing.

But the expense, noise, stink and especially weight still held the diesel OB back. And vibration dosn’t help. To power a sizable boat the torsional vibration rears it’s ugly head. Standard inboard diesels are few and torsional vibration is part of the problem. Except for small diesels like mine (37hp) torsional vibration is a significant issue. since weight is such a big factor for outboards the only easy way to tame torsional vibration is wa big heavy flywheel. But then there's the weight Issue usually slamming the door shut.

So if you consider many of the reasons together diesel engines still aren’t popular on small boats (except trawlers) it’s not hard to understand why diesels are great for tractors and trucks but for pleasure boats .. not so much.

 

[syjos]

Yanmar had a couple diesel outboards back 20 years ago but they were low HP and heavy. They were used commercially. I looked at one for a get home motor but the weight and cost kept me from buying one.

They are producing diesel engines using Germany's Neander Motors revolutionary Dtorque engine design. Dtorque engines were initially developed for motorcycles but other uses are coming.

A Dtorque 50 hp diesel outboard weighs 385 pounds.

The Dtorque has two connecting rods per piston and two counter rotating crankshafts resulting in a low vibration, high torque 2 cylinder, common rail, turbo engine.

 

[jleonard]

Yanmar had a couple diesel outboards back 20 years ago but they were low HP and heavy. They were used commercially. I looked at one for a get home motor but the weight and cost kept me from buying one.

Block Island used to have 2 of them on their pump out boats. I'm thinking they were 40 HP. That was a prefect application IMO. Lots of idle and barely off idle time.
They were a little noisy but not bad when compared to the older 2 strokes.
Talking with the operators back them they said they would go forever on a tank of fuel.

 

[smitty477]

Block Island used to have 2 of them on their pump out boats. I'm thinking they were 40 HP. That was a prefect application IMO. Lots of idle and barely off idle time.
They were a little noisy but not bad when compared to the older 2 strokes.
Talking with the operators back them they said they would go forever on a tank of fuel.

At one point Block had at least 5 and likely more but that was quite some time back - not sure why they moved away from them after the half dozen or so years they were in service.

 

[ben2go]

I looked into these a few years back. Most are not emission certified for the US. They are also about 3 times heavier than a four stroke gasoline equivalent.

 

[Sailor of Fortune]

I think if they ever get emission compliant in the US, the big market will be as pollution response boats owned by oil companies and commercial responders.

 

[mvweebles]

You're not the first to ask. Do they exist? Yes. Are they practical? No.

 

[Al]

https://www.mby.com/gear/cox-powert...300hp-diesel-outboard-engine-has-landed-99662

 

[FF]

These have DARPA bucks and are in the works for the military.

The diesel engine is 40 lbs for 40HP light enough to be used as an outboard.

 

[psneeld]

I think if they ever get emission compliant in the US, the big market will be as pollution response boats owned by oil companies and commercial responders.

The NRC vessel in Cape May had one maybe 10-12 years ago on their boom skiff IIRC.


Loved it but became an issue for repair and parts.


They may be on the rebound.... https://www.oxe-diesel.com/

 

[ben2go]

These seem to be the main players in outboard diesels.



https://www.oxe-diesel.com/


https://dieseloutboards.com/


Diesel Outboard Motors 5 to 80hp 4stroke 2,3,4 Cylinders water cooled


https://www.yanmarmarine.com/dtorqu..._medium=product-category&utm_campaign=Dtorque


https://www.mercuryracing.com/optimax-diesel-reporting-for-duty/


COX Diesel Outboard Motors

 

[healhustler]

Well, here ya go....low mileage Yanmar 36 HP Diesel outboard. Pricing pretty good too. This would be my get home engine if I could inspire the political will.

https://miami.craigslist.org/mdc/bpo/d/hobe-sound-outboard-motor-yanmar-diesel/7064863214.html

 

[psneeld]

I had to fix one for my boss one year as he made it part of a deal with a large environmental cleanup company that used them on their skiffs.


That was back in 2005 or so and parts were unavailable except through some very limited dealerships..could be different not but based on how many I have come across...my bet it is worse. I would check first but other than weighing a ton for it's size/power...it was a cool outboard.

 

[Jango]

Healhustler,


I would think the new Yanmar 50HP diesel could be a justifiable expense with a hydraulic jack plate / outboard lift as a get home engine. That would give me piece of my mind if I wanted to venture way off shore on an older single screw. From my searches over the years singles cost less, obviously less cost to maintain and great economical range.

 

[RT Firefly]

Greetings,
Mr. J. One of the arguments for a single power plant is lesser costs for maintenance and easier accessibility of components as compared to a twin installation. Consider how often one would be likely to service an outboard mounted in a less than comfortable location on the transom. An outboard is also much more exposed to the elements and sea conditions.



Are the savings realistic? Would one save that much in servicing a single inboard engine AND and an outboard as compared to twins? Would the added costs of purchase of a new diesel outboard AND associated mounting compare favorably with the replacement/repair of one of two twins?


It has been mentioned that 90%+ of engine failures are fuel related so one has to also consider a separate fuel supply for the outboard with sufficient capacity to enable a long enough run time to get you to safety or shelter.


There IS some merit for an outboard as a back up but seems a bit too complicated to me.


One last thing to consider. Is the vessel with the single capable of venturing "...way off shore"? Not too many are built or equipped for blue water as compared to the numbers of coastal cruisers available and are subsequently priced higher.

 

[Jango]

RTF,
Valid points on the outboard I thought as well. I was thinking though other than running every once in a while the a fresh water flush afterwards maintenance may be minimal. But I do know what salt air will do to machinery. Seen it often at many FPL plants in Florida. My preference is twins but have looked over a lot of singles on yachtworld and usually drool over the engine compartment room.

 

[Pete Meisinger]

They are out there. They are good, they are powerful. They are reliable and they will save you on fuel. They are available and they pass emission standards. They are backed with good warranties and there is service available.

They are heavy and they are EXPENSIVE!!

pete

 

[FF]

As with most boats engine selection , if you will run 1,000 or 2,000 hours a year , need over 300-350HP cont. or have range limiting fuel tanks , Diesel can make sense.


Otherwise , a modern gas inboard or outboard should be the low cost option.