Diesel Outboards

Discussion in 'Propulsion' started by Silverbreeze, Jul 4, 2016.

  1. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    Until a few years ago I had a boat with twin turbo diesels with mechanical injection.
    To lower the running costs I had an underground tank installed, filled up with heating oil (red diesel) with plenty of sulphur.
    When I sold the boat there still was a large amount of fuel left, so I decided to use that in my Kia Sorento common rail diesel and the Fiat Ducato RV. For over two years the vehicles have been on a red diesel diet without any problems except for the occasional "water in fuel" warnings, probably because the tank vent allowed some rain to get in when the weather was very bad.
     
  2. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    Why are you so stressed about the fuel quality? Bad experience?

    No I run a 1950 era DD 6-71 with H injectors , so never a problem with a Raycor 1000 and 2 filters.

    My concern is from the article in Professional Boat Builder that raises the problem of poor legal standards for fuel , and does offer a sort of solution.

    Multiple in depth filtration , which would be lots of added stuff to install and service in an outboard.
     
  3. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    what you can sell on the land and what you can sell on the water are 2 different things
    It has gotten very complicated for commercial vessels as multiple laws govern you and in stupid EU, dozens of laws where its almost not possible to prevent yourself from breaking the law either by using the wrong fuel or even having it in a tank that you dont use.

    http://www.yachtingmonthly.com/news/germany-fines-red-diesel-yachtsmen-3896
    http://www.cruiserlog.com/forums/f12/red-diesel-fines-in-europe-6048.html
    http://www.theyachtmarket.com/articles/general/red_diesel_and_its_effects/
     
  4. Capt Drake
    Joined: May 2015
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    Capt Drake Junior Member

    Many fuel suppliers provide clean fuel, unfortunately same can't be said about the retailers and how clean or well maintained they keep their tanks before selling it to you. That being said.

    Two tanks is not a bad idea, however, inconvenient solution. Lets say one tank ends up having bad fuel, if at any time one forgets to close a valve that will self balance tanks you'll end up with bad fuel in both tanks.

    Fuel filters are a good solution if you have a well laid out set up as Silver mentioned. Another solution for maintaining or making sure the diesel is kept clean is using a fuel polishing system.
    It can be set up for weekly polishing in which it will recirculate the fuel in the tanks. By using such system, when you operate your engines, the fuel passing through the filters has been pre treated and it will be cleaner thus filter life will be longer and quality and consistency of fuel reaching the engine will remain in optimum condition.
     
  5. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    "making sure the diesel is kept clean is using a fuel polishing system."

    Polishing only works well for inshore boats that do not see rough conditions.

    Any water in the tank may cause bugs to live at the fuel/water interface.

    The bug bodies and waste will stick to the tank walls and somply polishing the fuel does nothing to remove them

    Shake the tank a bit and the fluid motion can loosen this grunge to mix with the fuel and perhaps plug the filters.

    The solution is simple get rid of all the water in advance and use a bug biocide to be sure..

    No water requires at least a tank low point drain , or a hose fed to the tank bottom (usually way below the fuel pickup) to service the tank.

    The best is to install a marine fuel tank, (not just a box for fuel,) that has built in clean out ports as well as a servicible sump ,,, that IS serviced.
     
  6. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    Like Fred says... lots of filters. I have two engines. two fuel tanks, 6 filters. and day tanks.
    SO I filter when it comes is, then runs to large item filter, then it runs through a large micron racor, then through a smaller micron filter. I have everything duplicate, and the fuel on each engine comes from different sources. If one goes bad, I switch everything to the other tank immediately. If all this sounds silly it saves my neck about once a year. Most of the time the fuel comes with junk, water and even burnt oil.

    My next project is to get inside the tanks and clean them, there is always something in there. Stuff like fuel senders and hoses break down. On my truck, the plastic tank itself is breaking.

    So keeping your fuel clean is your most important mission with a diesel.
     
  7. keith_2500hd
    Joined: Jun 2016
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    Location: iowa,florida

    keith_2500hd Junior Member

    if you're running large enough fuel tank not to burn half of the fuel on trip. tanks in close to hull bottom, you're going to get condensation. your have to run a biocide and polishing setup, taking from low pickup. this will allow polisher to transfer water and trash to filtration unit. engine will normally run off pickup positioned above low pickups in fuel tank. old setup ran high volume lift pump, pulling through large water separator filters(large to smaller micron ratings, 30 primary then 10 or 5) the newer common rail run 1 micron to pressure pump. the old setup pumped extra fuel, performing polishing during engine run cycle and return to tank. in a boat I would always run a biocide, if you go through fuel use minimum treatment ratio.
     
  8. Capt Drake
    Joined: May 2015
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    Location: Florida

    Capt Drake Junior Member

    Fred, inshore or offshore boats will eventually end up in a marina or out on dry dock in "calm conditions", so a fuel polisher ran frequently will solve the problem. Their fuel filters can be set up with of various micron size filters and a water separator.
    If the boat will be in offshore for eternity; then a fuel centrifuge will be a solution for your water and dirty fuel issue. Otherwise a fuel polisher system works fine even with multiple tanks and avoiding the hassle of refueling on different locations.
     
  9. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    " boats will eventually end up in a marina or out on dry dock in "calm conditions", so a fuel polisher ran frequently will solve the problem."

    Depends , the usual setup is to tap into the existing engine fuel pickup (lazy and cheap) which is above the tank bottom , so any water is Never picked up to be filtered.

    With a pickup line that extends to the bottom of the tank, the water should be available to be removed.

    "then a fuel centrifuge will be a solution for your water and dirty fuel issue"

    These are wonderful , but expensive hunks of gear.

    For most folks a simple sump on the tank works as well with almost zero expense.

    The dirty fuel problem is 99% the fault of cheap boat builders that get away with installing a box for fuel, instead of a genuine marine fuel tank.

    Also at fault is the before delivery surveyor that does not inform the first purchaser about this long term maint hassle.
     
  10. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    YEP, same thing in Diesel trucks.
     
  11. Boatman1011
    Joined: May 2013
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    Location: Florida

    Boatman1011 Junior Member

    Does anyone actually have any experience with either of these manufacturers? I’ve talked to both at shows since 2018 and all I hear is they’re coming. Both OXE and Cox claim to be offering a 300 Hp by mid-year 2020 (now) but I can’t find anyone that actually has good experience with either.

    How is Cox going to keep a lower unit together with a 300 Hp diesel when MerCruiser, Volvo Penta and Yanmar are les than ideal on the I/O’s? I like to simplicity of the belt drive with OXE but I’ve watched their stock price since they went public 2 years ago and they don’t look to be hitting it out f the park. I do chartering and accumulate about 500 hours/yr so I think I can get payback on fuel economy but I’m nervous about taking a risk with such an unknown. I’d rather let someone else provide it before I take such a big chance. Thoughts?
     
  12. Silverbreeze
    Joined: Feb 2009
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    Location: Amsterdam

    Silverbreeze Bruno Tideman

    We are going to install both OXE 300 and COX 300 on identical boats so we can compare. Expected delivery early August. We have our RBB 900 hulls available in the workshop.
     

    Attached Files:

  13. Boatman1011
    Joined: May 2013
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    Boatman1011 Junior Member

    Thanks for that update, I’ll be interested to hear how they perform. I’m a little concerned with reliability on these new products with no proven track record. What are the prices for them?
     
  14. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    I can only assume they have step up gearing under the powerhead to reduce the torque in the gearbox?
     

  15. Boatman1011
    Joined: May 2013
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    Location: Florida

    Boatman1011 Junior Member

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