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Is a Diesel Outboard Right For Your Boat?

For years, buyers of boats in the 35 foot and over range had a decision to make when buying a boat; gasoline powered or diesel powered.  If you were buying a smaller boat, you pretty much had one option (with a few exceptions) and that was gasoline, especially if the boat you were looking at had an outboard engine.  

Now, things are beginning to change.  Several manufacturers, including Oxe, Cox, and Mercury Racing have announced new diesel powered outboards that rival some of the best-selling gas powered outboards on the market today.    I’m not talking about the 16 HP Yanmar that is on your neighbor’s sailboat.  These are serious outboards in the 200 to 300 HP range.  On top of that, they are quiet and smoke free.

When comparing diesel outboards to gasoline outboards, there are similar comparisons when doing the same with inboards.  Diesels are more expensive and heavier but they are also more efficient and will typically last a lot longer than a gasoline model.  A typical 200 HP diesel outboard can weigh 250lbs more than its gasoline powered counterpart.  This is a consideration when deciding how much weight you want hanging on your transom.  Of course, that same diesel engine will also provide you with a 30 to 40 percent fuel savings and last three times as long with less maintenance. 

So how long does it take to recoup the increased cost of a new diesel outboard with the fuel savings that you get?  That depends on how much you use it, but one thing is for sure.  If you are just a weekend boater, you probably won’t.  For this reason, manufacturers are currently focusing their marketing efforts on commercial and military customers.  There is also a big market to power mega yacht tenders because that saves the hassle of having to carry a gasoline aboard the yacht.   But, what if you are a fishing guide and you are on the water 5 or 6 days out of the week?  Or, maybe you are just luckier than your friends and you have the time to use your boat every day.  If this is the case, maybe a diesel outboard could work for you.

Here are a few of the diesel outboard options out there.


Cimco Marine is a Swedish company that has a line of outboards from 125 HP to 300 HP (the 300 HP model was just announced and may not be available as of the time of this article).  Much like what Mercury and Volvo Penta have done, Cimco has taken a GM block and converted it to a marine engine.  Their models are belt driven for smooth operation and also feature a hydraulic clutch pack instead of clone clutches which make emergency stops more easily done without damage to the engine or drivetrain.  

Cimco has Oxe distributors in the US and many other countries.  


Cox Powertrain is a European company that was created specifically to develop a diesel powered outboard for the British military.  Since then, they have started selling to the private sector. They also now have distributors in the US.  Rather than converting an existing engine design for marine use like other manufacturers have, they designed theirs from the ground up.  Cox claims that by doing this, the consumer ends up with an outboard that can handle a marine duty cycle without having to be excessively heavy.  The only model I can find at this time is a 300 HP model,

Mercury Racing

Yes, you read that correctly.  I know that the terms diesel and racing don’t typically go hand in hand but Mercury Racing has developed a diesel outboard engine.  It is based on the 3.0 liter Optimax platform and produces 175 HP.  The unique thing about this model is that it is a two stroke diesel and it uses a spark ignition system.  It was specifically designed for military use and apparently as of this time, is only available to the US military.  My guess is that, like a lot of other military technology, it will eventually be available to the general public as well. 

So, the next time you need to repower your outboard powered boat, you may want to think about a diesel and see if it is right for you.

If you have any comments on the idea of using a diesel outboard, please leave them below.

Happy Boating

Captain Frank


  1. I would love to have one on my boats..

  2. Antonio F. SanpereMarch 4, 2019 at 7:33 PM

    Only if you can carry all that extra weight.

  3. If it was a T/T a diesel yacht/ship and they could share fuel and I wouldn't need gasoline tankage, yes; otherwise, probably not.

    1. Antonio F. SanpereMarch 4, 2019 at 7:38 PM

      Richard Fischel agree. I tried an open boat with the 30 hp Yanmar diesel back in 2000. Heavy and noisy. The 3Gm engine vertical.

    2. Antonio F. Sanpere they are still a bit heavier but definitely not noisy anymore.

  4. Torque for sure.

  5. Large vessels (fishing vessels, cruise ships, even coast guards etc) have strict limits on the amount of gasoline and other highly flammable fluids that they are allowed to carry onboard. There is of course no/few restrictions on the amount of fuel=diesel that they may have. For these purposes the diesel outboard used on tenders for large vessels, is genius, as they will be able to use the same fuel.

    1. Cappe Grönblom Fuel limits?

  6. James Puckett yes. Pretty strict

    1. I think that he is referring to the carrying of gasoline for tenders and such. You may have a large Mega-Yacht which will of course be diesel powered but if you are using a 30 foot center console for a tender then it will have gasoline powered outboards. This will require you to carry gasoline on board the yacht to fuel the tender. If your tender was also diesel, that solves the problem of having to carry gasoline (which is ore dangerous) aboard.

  7. Safer and more reliable

  8. Look at the twist of those props


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