Diesel outboards

Discussion in 'Diesel Engines' started by Pericles, Jul 19, 2020.

  1. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    I have a 2004 Merc 50 4 stroke must be close to 2000 now. Runs good.
     
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  2. Boatman1011
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    Boatman1011 Junior Member

    I’ve heard of very few petrol outboards running 10,000 hours, and by EPA they are all classified as category 1. For the new Sea Pro commercial line it’s a 3,000 hour target. All of the petrol outboards are considered class 1 by EPA which is 10 year 1,000 hour life target. The light duty rated diesels also fall within the same category 1 EPA classification. To get up to a 10,000 hour commercial rating within category 1 they have be able to offer a 5,000 hour warranty. I certainly understand how to do math and can figure out the payback, I guess my point was from what I read on the Cox engine in a boat tested in comparison with the Yamaha F300 the fuel saving was <20% unless your running at WOT. At that rate with the low fuel prices you’d likely have to run the engine more hours that its even rated for to ever get payback. It seems risky until the reliability is proven in the market for a Few years.
     
  3. fallguy
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    fallguy Senior Member

    right on...this is the big reason...even if you get twice the fuel economy and better hours; I was still worried about the dual crank design of the ob
     
  4. Boatman1011
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    Boatman1011 Junior Member

    I’ve never, ever seen a petrol outboard go 10,000 hrs. But I’m sure there’s one somewhere. Still, I’ll bet you it’s less the .001 % of the product produced. How could a manufacturer make a profit by designing something to last 10x what the industry regulates them to? I deal with several commercial operators and they all remove and sell after 2,000 hrs because the risk of breakdown is simply too high.
     
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  5. Eric ruttan
    Joined: Jul 2018
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    Eric ruttan Senior Member

    Why can you not read and comprehend?
    P51 and 70 year old military designs that never compeated in the market, bought at any cost, and were constantly meticulosity maintained by a motivated force, are not General Aviation relevant.

    Can gearboxes work? Sure. Have they worked? Sure? Do they gave a great record in the modern age? Nope. Are there exceptions? Perhaps.

    Your continued advocation for your 'correctness' and ignoring problems with you arguments, your statements, and your facts, makes you seem silly.
     
  6. KeithO
    Joined: Jul 2019
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    KeithO Senior Member

    The surviving boxer air cooled engines preceded the Merlins and Allisons by many years. Simplicity is great, but it doesnt scale well. Thats why there are no boxer engines below 100hp because they cant be built light enough, nor can they swing a big enough prop. The newest engine to be a commercial success in recent history was the HKS 700 which was a 2 cylinder opposed design with a reduction drive so it could swing a decent prop. There have been no recalls on this engine and it has a decent TBO, so there are no real technical problems. Many converted MCC Smart turbo gas engines have been sold in Europe in the FK series of aircraft. A diesel version of the same powerplant has also been sold, but in smaller numbers compared to the gas models. Both have proven to be very reliable powerplants at less than half the cost of Rotax and in a market where Lycoming and Continental offer nothing at all.

    So, believe it or not, I think we are going to find that the majority of new aviation engines 100hp and below are going to have reduction drives. They just have to be properly designed. The number of aircraft built that need more than 400hp are so few that engine development could never be viable.

    The other thing is that regardless of how you want to spin it, WW2 was a technical arms race and there is no doubt whatsoever that had the water cooled V engines not been built, it could have ended badly for a lot of people in Europe and across the Pacific. The same features that today are so criticised in general aviation, without a doubt made possible airplanes with the best performance ever achieved in the piston engine category. So the technology has been tested at the sharp end of the spear in actual combat and proved itself to be superior. Obviously there is an application range from 500-120hp where direct drive engines remain a good fit, especially in an industry as litigious as general aviation.

    The bottom line is that this series of outboards has a transmission. It doesn't matter whether it has belts, spur gears, helical gears or whatever, its obviously not a direct drive longtail kind of engine. The transmissions used in regular outboards are pretty crude, yet have been considered acceptable for decades. Imagine if Honda next month announced that they were going to introduce a CVT transmission into their outboard lineup ? Given how long CVTs have been in commercial production in cars, it would not even be a technical accomplishment, just a new application. If it happened, this company would be dead overnight because their fuel economy benefit would probably vanish or the break even point on their outrageous prices could never be reached. We ll just have to hope that one of the regular outboard manufacturers gets with the times and starts offering something newer than 1950's technology...
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    2000 hours on any large outboard represents a small fortune in fuel used, way beyond the purchase price and servicing costs, any calculation of the viability of diesel outboards for a particular application, involves a number of factors to be weighed up, even including whether you want to cop the smell of diesel fumes.
     
  8. Boatman1011
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    Boatman1011 Junior Member

    Post a few links of outboards that have 10,000 hours, or 5,000 hour outboards that are still in good shape and for sale. There’s NOT a commercial registered petrol outboard on the market, 100% of them are rated for a pleasure, 1,000 life. You realize the average annual usage is 50 hrs/yr, and most of the engines struggle with corrosion long before wear-out of the rotating assembly or gear train. This was the original intent of my question - even if the diesel power head and drivetrain can actually hold up for 5,000+ hrs, corrosion will still be a major hurdle for any outboard product. With the big manufacturers they’ve been a around long enough to know how they hold up to corrosion but these new diesel outboards are so scarcely located around the world its difficult to understand how well they deal with this major hurdle.
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  9. Boatman1011
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    Boatman1011 Junior Member

    I’m not sure that’s completely correct unless your running 2,000 hrs at WOT. All the manufacturers light-duty warranties prevent you from running more than 1 hour out of 8 - 12 at WOT. So it all comes down to the boat hull and duty cycle your running. With a 70% duty cycle load it takes about 5,000 hrs at todays fuel prices where petrol and diesel are priced about the same here in the U.S.. However, commercial operators in Europe have a benefit that diesel is cheaper than petrol and they can claim the VAT back for diesel.
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    Running WOT is bad practice full stop, I am talking cruise speeds on plane. Naturally if you cruise for half an hour, to fishing grounds, then troll for fish for six hours, then half an hour cruise home, things are different.
     
  11. Rumars
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    Rumars Senior Member

    I am really interested to know how some of you come to expect such high hours from this engines. I am talking about the 300hp ones, wich are standard car engines on their car horsepower ratings. Just to be clear, Oxe uses the BMW B57 engine, Cox the Ford 4.4l V8 and Klaxon the Steyr SE6 (M16UI). Now a modern engine like this ones would be expected to run 500 000km in a car before exhibiting any problems. To get 5000 hours out of one as an outboard would mean that 1 hour of cruising speed is like driving the car at 100km/h on the freeway. That is a fact I have trouble with, keeping even a heavy SUV at that speed is not going to use even half the power. You can compare the fuel rates, that gives a clear indication of used power. And if the outboard uses the same power as the car (with similar fuel consumption) we have several problems. First is buying a much bigger engine than needed and driving around additional weight, and second the fuel consumption difference to a gas outboard drops and it takes much longer to recoup the price difference.
     
  12. KeithO
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    KeithO Senior Member

    The aviation diesels just made it to 2100 hours a few years ago, the Continental CD 135 specifically. And those motors no longer have any automotive parts in them, not even the block. And there are several parts that require prior replacement at 1200 hours like the transmission, alternator and fuel pump. At full hours they have to be replaced, there is no overhaul program.
     
  13. KeithO
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    KeithO Senior Member

    Did your ego get hurt somewhere ???? Awful touchy about someone else's product...
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    What the odd exceptional case may be, is less interesting than what the average result is. Most outboards in recreational use would be lucky to get to the 2000 hours, the old two strokes might have got to 1000 and needed a re-build.
     

  15. brendan gardam
    Joined: Feb 2020
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    brendan gardam Senior Member

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