Diesel outboards for NC’s and MerryFishers

[lynnardm]

This thread is for discussion of the new diesel
Outboards that are in development and their possible suitability for a jeanneau NC or MerryFisher.

I am aware of two companies that have or are developing large diesel outboards. The companies are OXE and Cox

Cox is developing what they call the CXO300. This may be a good fit for something like an 895. Production is planned to begin the 4th quarter of this year. Captain Ron and I will be going on a boat test demo of a preproduction engine on Monday. We will give a report of our observations.

Capt’n Lynn

[timbray]

One suspect these things are going to be quite a bit more expensive than the Yammie 150/200/250s on the backs of all the Jeanneaux, and for that matter, on the back of like a third of the powerboats in my marina.  So you'd need to do a lot of cruising to see any fuel savings.  What are the other good reasons for switching?

(Also, these days, thanks to ethically-challenged auto makers, diesel is starting to have a bad image from the environmentalist angle - I wonder what the emissions story is?)

[dogbreath]

I copied the following from www.boats.com/reviews/cox-cxo300-diesel-outboard-review/

"Running with a diesel outboard will net you a boost in reliability, longevity, and economy. So, why doesn’t everyone do it? Aside from initial cost – the CXE300 is expected to go for around $50,000, or about twice the cost of a gasoline outboard with the same amount of power – weight is a big issue. And yes, these engines do weigh significantly more than their gasoline counterparts. The new 4.6-liter Mercury V8 FourStroke, for example, has a listed weight of 538 pounds; Yamaha’s F300 Offshore V6 weighs 562 pounds; and the Suzuki DF300A tips the scales at 639 pounds. The Cox tops them all significantly, with a dry weight of 826 pounds."

I own a NC 895 with twin f200s. I like the redundancy of twin outboards, for the peace of mind. I also enjoy (o.k. - need - lol) the maneuverability twin outboards provide. Given that I can purchase two Yamaha f200 for $38,000, considerably less than one CXE300, the math of a single diesel outboard does not look favorable to me as a recreational/pleasure boater.

The closing paragraph in the above linked article states: "Will we see diesel outboards replace gasoline models in marinas all across the nation? Not likely. As we’ve noted they have plenty of down-sides as well as advantages. However, the Cox is likely to fill a very real niche in the boating world. Commercial outfits and governmental agencies that put thousands of hours a year on their engines are likely to find a diesel outboard quite attractive. And there’s a very real draw for those tender and fishboat owners, too."

Dogbreath

[lynnardm]

Capt’n Ron and I did get out for a demo of the COX CXO300 last week in Port Orchard Wa. The engine was a prototype and detuned to around 250 horsepower. They had a 16” dia 3 blade prop. It was on a police style heavy aluminum boat with an enclosed aluminum helm/salon. In size and weight it was a bit less than an 895. Engine noise was reasonable, perhaps a bit more than a Yamaha f300. We did take decibel readings but since this was a prototype I’m not including them at this time. We did a slow start and then cruised slowly up to around 35 mph. When we asked the operator to do a fast hole shot he said he couldn’t as the engine would overpower the prop and over-rev. I then asked to do a fast acceleration from about 20 mph and same answer. This was no surprise. Given the small size of the prop with an engine with this much torque this is what I would expect. Larger diameter and more blades are called for. The distributer plans to be back in the beginning of the year with a production engine. Hopefully they will have an adequate prop installed. So in summary, So far it appears like a great design but I have a lot more to learn about this new diesel and look forward to testing a production engine. Before closing, I do have one comment about the article posted above regarding weight. The author compared the CXO300 to other 300 outboards. This diesel engine has power (torque) significantly above gas engine setups like twin Yamaha 200’s or a single 425. I expect speed to be similar these setups. So I consider the diesel at a bit over 800 lbs to be a weight savings.

Capt’n Lynn