Would you pay for this alternative engine....

It weighs 60% more, costs twice as much, but lasts three times as long and uses 25% less fuel.

That is the Cox 300 hp diesel outboard compared to a gas outboard. Weight is around 825 lbs and price is going to be around $50,000.

It struck me before saying "no", that we do that every day with diesel inboards. They're substantially more expensive and heavier than gas engines but we've come to appreciate the benefit.

Cox showed their 300 at FLIBS on an Intrepid center console.

I can see some benefits for certain users.

-> Offshore fishing boats can benefit from extended range and reducing operating costs.

-> fishing charters (6 pack) can benefit from increased duty cycles and range.

-> high duty cycle usage (Harbor master, pump out boats).

I think it all depends on how much you use them and how hard you run these engines.


If you run it at 150 hp or less and use it 300+ hours a year then it may make some sense. The fuel economy will pay for a lot of the extra costs and it may very well get three times the life of a gasoline outboard. Another plus is the extra range that the reduced fuel consumption allows.



But if you run the snot out if it like a lot of outboard owners do and only use it 100 or so hours a year then neither the fuel economy nor the reduced longevity at high power usage will pay for itself.


David

I hope they have corrosion issues under control. Doubt it has closed cooling. Outboards last on avg 10-15yrs in sea water and corrosion is usually what takes them out.

That's a lot of weight per 100 HP, on the transom. Could see commercial applications where weight isn't an issue. User plans to put a lot of hours on the engine at 150 HP, and the ability to reduce draft is a big advantage. I'm visualizing a shallow draft or pontoon style steel push boat. Would think that could be a good market if they offered a tall gear lower unit that could swing a larger diameter flatter pitch prop. Also could see that same configuration being a winner for the 25 to 30' Seatow or TowBoatUS boats.

Ted

Will there be qualified repair techs. in your area and in areas you plan to cruise to?

What is the proof that it will last 3X longer? Just because its diesel does not automatically generate longevity. They sure aren't tractor engines!

I would wait to see how they hold up in practice. Check with me in 5-10 years. For me it’s too critical and too expensive a part to take much risk.

They were very impressive, as was the Intrepid, as usual.
There is certainly a market for these engines, and all the reasons not to buy them do not apply to the target customer.

BandB said:

Cox showed their 300 at FLIBS on an Intrepid center console.

Click to expand...

Not for me!

The next generation of heavy fuel (diesel or kerosene) will weigh about 1lb /hp and with 2 moving parts be way cheaper to mfg.

They offer a 30% savings in fuel burn at max hp which gets even better at part throttle.

5 year wait unless the Chinese jump in.

Diesels last longer for two reasons, one inherent and the other designed in.


The inherent reason is that diesel fuel is a decent lubricant. It helps reduce wear on things in contact with the fuel like valve stems and seats and to some degree piston rings.


The other is that diesels are built tougher. They have more bearing area, stronger bearing webs (not distortion), crankcase walls etc. Yes you could build a diesel probably as light as a gasser but it wouldn't last long.


The fact that this engine weighs 60% more than a gasser seems to indicate that they didn't cut corners although part of that weight may be a coolant system with a water to coolant heat exchanger.


David

Diesel outboards have been around for some time now. I met a fellow (KK42 owner) who had a diesel outboard and swore by it. Expensive but it was quite old and still clunking along. Not sure of the make or HP.

Wouldn't have one on a bet. Cost and weight rule them out. As for dependability....humbug. The new electronics are great. Even an old model with a carb can run forever. Easy to work on and dependable. What more do you want from an outboard? But that's me.

On a trawler, best weight is in the middle of the boat, not on the transom. Meaning the engine should be in the middle of the boat.

2 of these's on a big cat would free up a massive amount of space

Is it Cox, or Oxe? I’m at METS and talked to the Oxe guy this morning. It’s Swedish built, based around a GM 4 cyl diesel. To my surprise, it’s had EPA cert and been selling in the US since 2014.

It is belt driven in two different locations. Apparently a shaft drive as used in typical outboards can’t handle the torque. There is a belt drive from the engine to the transmission which is roughly middle of the lower unit. Then another belt drive from trans to prop shaft at the bottom of the lower unit. It also eliminates the bevel gears which apparently are a weak spot.

Interesting tech. I didn’t ask about price.

twistedtree said:

Is it Cox, or Oxe? I’m at METS and talked to the Oxe guy this morning. It’s Swedish built, based around a GM 4 cyl diesel. To my surprise, it’s had EPA cert and been selling in the US since 2014.

It is belt driven in two different locations. Apparently a shaft drive as used in typical outboards can’t handle the torque. There is a belt drive from the engine to the transmission which is roughly middle of the lower unit. Then another belt drive from trans to prop shaft at the bottom of the lower unit. It also eliminates the bevel gears which apparently are a weak spot.

Interesting tech. I didn’t ask about price.

Click to expand...

This one is Cox and, yes, Oxe has been around awhile. The use of the term "selling" is one that might be argued as I know it's been offered for sale, but not sure how many, if any, have actually sold. So far I don't see any outboard diesel manufacturer gaining any traction. Teaming with a builder is probably a good approach, but I don't see most Intrepid buyers even considering the possibility. Top end speed is far more important to them than torque or fuel consumption. That's why inboards and even pods have had no success in center consoles.

I'd suggest they put one on a loop boat of some size and quality and then invite all the boating magazines to follow as they chronicle the year. However, that's a big gamble that it goes trouble free. But that to me was genius on the part of Beneteau and the Swift Trawler, doing just that.

Otherwise something like a huge promo deal to Sea Tow or Tow Boat US to outfit a bunch of boats and test, all at the manufacturers expense or at greatly cut prices (like 75% discounts, 25% of normal).

Building the greatest mousetrap has no real significance if you can't sell anyone on it.

djmarchand said:

I think it all depends on how much you use them and how hard you run these engines.


If you run it at 150 hp or less and use it 300+ hours a year then it may make some sense. The fuel economy will pay for a lot of the extra costs and it may very well get three times the life of a gasoline outboard. Another plus is the extra range that the reduced fuel consumption allows.



But if you run the snot out if it like a lot of outboard owners do and only use it 100 or so hours a year then neither the fuel economy nor the reduced longevity at high power usage will pay for itself.


David

Click to expand...

I do not understand this....
If you run the diesel at say 100hp demand @ 300 hrs and the diesel gets 25% better mpg the difference would be about 420 gal per year.
If you run the diesel at say 250 hp demand @ 100 hrs and the diesel gets 25% better mpg the difference would be about 350 gal per year.
Where we are the costs of gas are always a good deal more than diesel.

With all that said I have not owned an outboard powered boat that could successfully support that extra weight on the transom without problems.

Guess I'm kind of lost on this conversation, and the consideration of outboard power for other-than dinghy propulsion. What is the applicability of this Cox diesel outboard to the kind of boating this forum aspires to? From the Cox website, the outboard is shown aboard boats much more suitable to outboard power (center console, fast movers in general terms). Even at 800+ pounds, perhaps a fit to those kinds of boats.

But again, it's not clear how these engines, and outboards in general, have applicability in "trawlers" (whatever THAT means). These boats are typically designed for long distance, open water (which includes coastal) voyaging, carrying significant hotel loads and significant hull volume for comfortable passagemaking. Is it reasonable that an outboard will ever be suitable for this market?

It appears there is a subset of the "trawler" market that values high speed, albeit at VERY high cost compared to more traditional cruising powerboats.
And a subset that values overland transport to reach cruising destinations. And a subset that is willing to forgo amenities in favor of reduced cost. I get all that. And for these markets, perhaps such a high-speed diesel outboard makes some sense.

But good grief. Hanging one of these monsters off the transom of a larger (40'+, for instance) heavy displacement "trawler" and expecting a miracle to happen simply is lost on me. For example, the Cox outboard is optimized for high speed operation. It swings a relatively small propellor, turning at a relatively high RPM to achieve it's rated power. Appropriate at 30+ knots perhaps, but at 10????

Servicing this thing will be problematic for those of us that operate our boats in the water 100% of the time. Even a simple oil change is a genuine PIA with the boat in the water. Lower unit service is impossible. Even routine oil and coolant checks require hanging over the transom, removal of an awkward and heavy engine cowling (and not dropping it overboard!), and contortions to simply reach the dipsticks. Have multiple outboards? Multiply these contortions accordingly. Or Break Out Another Thousand to let your marine professional do so, and cruise via cellphone and credit card.

As mentioned by others, diesel outboards have been around for generations. There lack of significant penetration into the recreational outboard market even in vessels that are appropriate to outboard power, is apparent. That may change in the future, but I remain skeptical.

And unless and until the outboard motor manufacturers, the "trawler" designers, and the builders decide to collaborate on suitable hull and powertrain variants that can accomodate outboard power for coastal and offshore voyaging in a "trawler", this topic is moot and simply academic to me. Introducing this topic to this forum is fine, and that's what this forum does best. But for what my opinion is worth, I suspect it will remain a topic outside the mainstream, at least in this forum, and certainly for me.

Regards,

Pete

jungpeter said:

But again, it's not clear how these engines, and outboards in general, have applicability in "trawlers" (whatever THAT means). These boats are typically designed for long distance, open water (which includes coastal) voyaging, carrying significant hotel loads and significant hull volume for comfortable passagemaking. Is it reasonable that an outboard will ever be suitable for this market?

It appears there is a subset of the "trawler" market that values high speed, albeit at VERY high cost compared to more traditional cruising powerboats.
And a subset that values overland transport to reach cruising destinations. And a subset that is willing to forgo amenities in favor of reduced cost. I get all that. And for these markets, perhaps such a high-speed diesel outboard makes some sense.

And unless and until the outboard motor manufacturers, the "trawler" designers, and the builders decide to collaborate on suitable hull and powertrain variants that can accomodate outboard power for coastal and offshore voyaging in a "trawler", this topic is moot and simply academic to me. Introducing this topic to this forum is fine, and that's what this forum does best. But for what my opinion is worth, I suspect it will remain a topic outside the mainstream, at least in this forum, and certainly for me.

Regards,

Pete

Click to expand...

First, in the world at large, outboards are the most common propulsion system and recently have been gaining share. How does that fall into the trawler world? Well, Beneteau is spending tons of money to build and promote their new Antares line. That's 21 to 27' and in effect a smaller, less expensive cruising boat than the Swift Trawler. Wasn't all that long ago, everyone laughed at the concept of a Swift Trawler, but it's become probably the largest selling trawler type boat on the market. We've seen more efforts into building trawler types with outboards. A 27' Antares comes with up to 2 x 200 hp so a single 300 hp diesel wouldn't be adding excessive weight. In fact, if a manufacturer were to work a deal with Beneteau for a special diesel version at no added cost, I suspect Beneteau could make it a success. Perhaps one of these diesel engine manufacturers ultimately is purchased by a boat builder.

I've heard many times on this site people say firmly they'd never own a gas powered boat. While I don't agree with that, I know there are a lot of people who feel that way so perhaps they'd like these.

A 27' Ranger Tug was matched with a 300 hp Yamaha. I don't see a real issue with a 300 hp diesel even with the extra weight if the boat weight distribution was right or made right.

Outboards are gaining everything. We now have center consoles up to 65' with five 627 hp outboards. Now, take that same boat and outfit it for slower cruising and place three 300 hp diesel outboard on the back and perhaps a nice boat.

Right now, I see the big issue original purchase price. However, life of engines is important to some outboard purchasers. Tow boats outfitted without outboards sure go through a lot of refits. We own a 39' Contender with triple 300's and it's had very high usage and the engines already exceeding normal lives. We're trying to decide whether to repower or replace the boat. I noted on the SeaVee web site looking at used boats they have that a lot of buyers are trading at around 1000 hours. A lot of used CC's are repowered so basically new engines. Would the owner have kept them if the engines were longer life engines?

Now, I don't think diesel outboards will ever be a success with the current companies offering them. They need a lot bigger money behind them. They need someone like Volvo or Mercury or Yamaha to jump on them. Before you say Volvo doesn't do outboards, they bought Seven Marine so they do very large outboards. Oh, a 627 weighs 1094 lbs.

Outboard power on coastal cruisers is very close and five years from today you'll see a lot of them out there. Another boat I'll mention is a 36' Aquila Power Catamaran. For those looking for loop boats, worth considering. Twin engines from 200 to 350 hp. Maximum speeds from 27 to 37 knots depending on engines. 2 cabins, 2 heads. Outboards are gaining everywhere. As to diesel outboards, I don't see anything happening there as long as it's just the current players.

I agree they make sense on smaller trawlers. If nothing else, recovering the interior engine space and using it for living space is a big win.


I'm no naval engineer, but do know that a larger diameter prop is more efficient, and can deliver more power to the water. With fast boats this is less of an issue because a smaller screw can turn quickly and be in pace with the boat's speed. But for slower boats where the power needs to be delivered at slow speed, I suspect there is a cross-over point where the small prop of an outboard just can't effectively deliver the power. I know work boats that struggle with this today. Not sure where that cross-over point will land, and how it will move over time.


Regardless, it's interesting to see. The OXE guy I talked to said their US customers are currently all government and commercial, which makes sense.


BTW, I wonder whether these various diesel outboards are independently developed, or if it's not the same machine being sold under different brands and channels?

twistedtree said:

BTW, I wonder whether these various diesel outboards are independently developed, or if it's not the same machine being sold under different brands and channels?

Click to expand...

Answered by own question. Nope, they are all different.

Yanmar will be bringing a 50 hp to the US market sometime next year.

https://www.yanmarmarine.com/News-detail/YANMAR-LAUNCHES-THE-DTORQUE-111-TURBO-DIESEL-OUTBOARD/

Heave to wait and see if this is a good thing. Not having two fuels on baord for large boats a plus.

Rough Magic said:

Yanmar will be bringing a 50 hp to the US market sometime next year.

https://www.yanmarmarine.com/News-detail/YANMAR-LAUNCHES-THE-DTORQUE-111-TURBO-DIESEL-OUTBOARD/

Heave to wait and see if this is a good thing. Not having two fuels on baord for large boats a plus.

Click to expand...

Very interesting to see all performance specifications compared one to one vs a similarly sized gas engine.

Since for many here that would be on a dinghy, a comparison of inboard RIB's, a Williams 445 which comes with a gas by Textron or diesel by Yanmar. 100 hp gas vs 110 hp diesel. Hopefully, the outboard can overcome the disadvantages of diesel. On that boat, the gas version weighed 957 lbs and the diesel version 1661 lbs. The gas would run 40 knots and the diesel 35 knots. Range in the diesel was about 15% greater. The diesel cost 20% more in the boat.

Now, I found a couple of things interesting on the dTorque. First, I can't find the weight mentioned anywhere. Maybe I'm just overlooking it. Second, their target is workboat. That makes sense as the use better able to accommodate the weight and willing to pay the extra to get the longer life. I can't see the 50 hp diesel having a place on small RIB's or on other dinghies.

Seems it could be a good choice for a semi displacement pocket trawler. I remember reading it weighs 398 or 400 lbs.

Rough Magic said:

Yanmar will be bringing a 50 hp to the US market sometime next year.

https://www.yanmarmarine.com/News-detail/YANMAR-LAUNCHES-THE-DTORQUE-111-TURBO-DIESEL-OUTBOARD/

Heave to wait and see if this is a good thing. Not having two fuels on baord for large boats a plus.

Click to expand...

Basically the Neander design. I guess Yanmar bought Neander.

It is a two cylinder four stroke, but with a neat twist: Dual counter rotating crankshafts. This allows nearly perfect dynamic balance. In a normal single crank 2cyl engine, the balance is horrible. Like really bad. I have not seen or heard this thing run, but looking at the design I think they are on to something sweet. We shall see.

Depressing that the Yanmar page states that this is not EPA certified. Probably due to NOx emissions. Denying such a fuel efficient machine market entrance due to NOx in the marine environment just seems silly. How many of these are going to be running in urban environments where NOx is an issue? Maybe one or two as water taxis in a big city. Burning a few gallons a day, with the resultant NOx how many grams?

Kind of like wood chippers now having high tech particulate filters and NOx catalytic reduction. How many wood chippers running in urban areas and how many grams of pollutant are prevented by such expensive gear?? Geez.

Rant over.

BandB said:

It weighs 60% more, costs twice as much, but lasts three times as long and uses 25% less fuel.

That is the Cox 300 hp diesel outboard compared to a gas outboard. Weight is around 825 lbs and price is going to be around $50,000.

It struck me before saying "no", that we do that every day with diesel inboards. They're substantially more expensive and heavier than gas engines but we've come to appreciate the benefit.

Cox showed their 300 at FLIBS on an Intrepid center console.

Click to expand...

$50,000 is about the cost of the diesel-powered cruisers I am looking at so not an option for me. I as a low hour per year, boater can't see that engine being viable for me. I do plan to cruise the loop, but even that would take a few trips round to make that diesel OB worth it.

Originally Posted by Rough Magic
Yanmar will be bringing a 50 hp to the US market sometime next year.

https://www.yanmarmarine.com/News-de...ESEL-OUTBOARD/

Heave to wait and see if this is a good thing. Not having two fuels on baord for large boats a plus.

Click to expand...

Since we have two 50hp Suzuki outboards hanging on brackets on our boat, I looked into this further and downloaded the owner's manual.


The gasoline Suzuki 50hp weighs 102 kg (225 lbs). The Yanmar diesel 50 hp weighs 175 kg (386 lbs).


Too heavy for our boat.

Miz Trom said:

Since we have two 50hp Suzuki outboards hanging on brackets on our boat, I looked into this further and downloaded the owner's manual.

The gasoline Suzuki 50hp weighs 102 kg (225 lbs). The Yanmar diesel 50 hp weighs 175 kg (386 lbs).

Too heavy for our boat.

Click to expand...

Is it?

I just did a test to convince the dealer I bought his demo Pompano 23 from to order a 100 lb heavier 90 hp engine vs the 250 lb 70 Yamaha that I have.

I shifted 150 lbs back to the transom underway to see how much the speed dropped. I was pleasantly surprised to see only a 0.1 to 0.2 mph speed drop at a 15 mph starting point. This was for a less than 3,000 lb boat with full fuel, gear and two persons on board. I could get that speed back by revving another 100 rpm which represents about 3 hp more.

My boat has a similar hull shape to yours and is also built light. The TT35 weighs about three times mine and another 320 lbs on the transom might not be a killer. You will probably lose about 10 hp at 15 mph due to the increased weight on the transom.

I am not suggesting that the Yanmar outboard diesel is a valid alternative for your boat, only that weight may not be the killer you think it is.

David

djmarchand said:

I am not suggesting that the Yanmar outboard diesel is a valid alternative for your boat, only that weight may not be the killer you think it is.

David

Click to expand...

I would say on 90% of boats that carry twin 50's, adding the 322 lbs of twin diesels wouldn't be a huge issue, but on Miz Trom's boat it absolutely would be too much, based on issues and challenges she already has.

I would think on most dinghies it would be an issue both in running them and in lifting and storing.

I would think on most workboats, it would not be an issue and this is where it's really targeting.

Now, I think your testing is very smart. We worried on a boat about weight we intended to add such as a second generator, a freezer, items beyond the builder's norm. Prior to doing so, we took weight and placed it on the boat in the locations and took the boat out and ran it with that weight.