COX 300 hp diesel outboard motor

[Nick14]

Apparently COX has a 300 hp diesel outboard motor.

https://boattest.com/boats/front-runner/26cc-w-cox-cxo300-diesel-power-2023?utm_medium=email&_hsmi=381796731&utm_content=381796731&utm_source=hs_automation

It's not cheap. I've seen prices on line quoting $55,000-$89,000 for one. But then that's comparable to a 300-ish hp Cummins 6.7 diesel, and even cheaper when you consider the usually stratospheric high installation costs of replacing an inboard engine.

Outboard power is all the rage with gas engines. At the recent Newport Boat show it seemed like most of the powerboats under 40-ish feet are now outboard powered, and some even bigger ones sporting an astonishing 5 or even humongous gas outboards hanging on the transom (how would you even go about flushing so many motors? It would take all day).

Too Much Power? 5 or 6 Outboard Engines Boat Trend - My Boat Life

Boat brands are opting for the trend of more power by equipping luxury center consoles with 5 or 6 outboard engines

www.myboatlife.com

Will trawlers or other cruisers follow suit with diesel outboards?

 

[rslifkin]

Personally I wouldn't want them on a trawler or similar. From a weight distribution, stern water access, and maintenance access perspective I have a strong preference for shaft drive inboards. Just about anything else compromises at least one of those criteria. And for maintenance access, it's a few concerns. Outboards, pods, etc. all increase the number of maintenance tasks that require a haulout and also increase the chance of needing to call in a factory trained tech vs being able to DIY.

 

[Gdavid]

I doubt trawlers would be the best application for these diesel outboards, but planning cruisers like Ranger Tugs and Cutwaters which have several designs already configured for outboard would make sense. I could also see a case for outboard diesels on first responder craft.

For a displacement or semi displacement trawler, while they could be made to work, I would see the small displacement and lack of freshwater cooling reducing the expected service life. Additionally, a non-planing trawler is more likely to find itself pitching heavily in a sharp chop which may allow the prop to cavitate. We try to avoid these conditions, but if I was stuck in really nasty stuff, losing thrust or fear of damaging my engine as the motor comes clean out of the water is a concern. On a planning boat, the bow rises pretty early with acceleration, allowing the stern to dig in, I don't see a large trawler behaving this way.

I'm sure there will be some, it just doesn't appeal to me.

 

[Nick14]

Huh… I have the opposite perspectives. I agree stern access is blocked with outboards, but seems to me engine access, maintenance, and repairs are all much easier with outboards (to say nothing of the vastly easier replacement).

Unless you’re lucky enough to have a big boat with a true walk-in engine room, most machinery spaces on medium size boats are a ‘hands and knees’ crawl space. As it is on my boat. When I was younger that was no problem. Now, thanks to the delights of osteoporosis getting on my hands and knees in a crawl space is an invitation for much pain and being laid up for days popping Naproxen’s like M&M’s. Not fun.

Friends of mine have outboard boats. Most routine maintenance and checks are done standing up, or sitting next to the engine. Prop issues are addressed simply by tilting the motor out of the water instead of needing a haul out. It’s painless (pun intended) in comparison, and very different from most inboard layouts.

Weight distribution is important. You couldn’t take an inboard boat, delete the engine, and just hang outboards on it. But with proper engineering many boats have been successfully reconfigured to outboard power (Back Cove, True North).

I’m not sure about outboard power for full displacement boats. A high speed engine and prop would seem to be the opposite of the slow turning, high torque, big prop that goes best with full displacement speeds. But for semi-displacement or full planing, could be ideal.

I think and agree your comments very much apply to pod drives, which I personally would never own even if given to me as a gift. But outboards seem to have many advantages for some applications, boat types, and owners.

 

[Blissboat]

Diesel outboard(s) inspire out of the box (or out of the boat) thinking. Repowering a gasoline powered boat is an interesting potential use case. Overcoming the effects on the vessel's trim angle ought to be manageable, as gasoline engines tend to weigh less than inboard diesels, and there'll be all that newly liberated real estate in the engine compartment.

The COX motors are big, heavy and expensive. OTOH, an outboard is relatively easy to snatch off the boat for repair or replacement.

Those of us who like trawler-type boats, at least in my case, are attracted to protected running gear. Outboards are incompatible with that, given the expensive lower unit sticking down below the bottom of the hull where the propellors have unimpeded water flow. I think Gdavid is right in Post #3 above - we're unlikely to see a lot of shiny new outboards hanging off the transoms of trawler yachts.

 

[rslifkin]

The point about limited prop size and pitching in chop are definitely a concern.

For maintenance, some stuff on outboards is easy, but then some stuff like a gear oil change can't be done in the water. And that's often an every 100 hours thing on outboards. For some use cases that would mean multiple haulouts per year for maintenance. From that perspective, I'd much rather crawl over to a trans, sit down next to it and change the fluid.

 

[Gdavid]

From the boat manufacturing side, I could see the appeal, and it is at least in some part responsible for the growth in prevalence of larger gasoline outboard boats (as well as owner preference). The proper configuration of an inboard drive train is critical to the success of a boat, and it is easy to foul up the installation. The manufacturer is significantly dependent on the engine and transmission manufacturers in turning out a well-functioning boat and when there is a vibration in a new boat, there is a lot of finger-pointing. An outboard negates a lot of these challenges and is attractive for manufacturers.

 

[PierreR]

I predict you will see just that. Trawlers with diesel outboards coming out in the next 5 years with swim platforms designed around them. Why? For most boaters maintenance and breakdowns and hiring it done are the single biggest point of stress and worry. That stress point alone is why people buy new boats. They think they are like new cars, good right out of the gate and yacht salesman are going to tout the advantages and paint pictures of gunkholing in two feet of water and all the extra space in a shorter hull.
I predict they will sell two to one over inboard trawlers.

 

[Figment]

There is also much to be said for getting the noise and heat out of the middle of the boat and hanging it out back.

I'm not instantly on board with the idea, but I'm certainly open to it.

 

[O C Diver]

At a quick glance:

866 pounds plus bracket on stern.
100 amp alternator.
Small propeller diameter.

I can see this for a go fast planning hull but not a liveaboard trawler. As mentioned, the propeller size would be totally wrong for a displacement hull. Taking a current trawler hull design wouldn't work do to the tremendous weight shift astern. Also, the depth of the average transom (as a single engine application) wouldn't work without a bracket (moving the weight further out). Then factor in the 300 HP, as being too much (for a single application) until you exceed 50 to 60'. At that length the risk factor for dunking the engine in heavy seas becomes very real. Lastly, a 100 amp alternator for a trawler with a house bank is a joke at best.

Ted

 

[Notorius]

What about reliability of this COX engines ? There is no long statistic.

 

[Portage_Bay]

From the boat manufacturing side, I could see the appeal, and it is at least in some part responsible for the growth in prevalence of larger gasoline outboard boats (as well as owner preference). The proper configuration of an inboard drive train is critical to the success of a boat, and it is easy to foul up the installation. The manufacturer is significantly dependent on the engine and transmission manufacturers in turning out a well-functioning boat and when there is a vibration in a new boat, there is a lot of finger-pointing. An outboard negates a lot of these challenges and is attractive for manufacturers.

People far more knowledgeable about the boat building industry than I support this. I won't buying anything that new during my remaining boating years so it doesn't affect me.

 

[PierreR]

At a quick glance:

866 pounds plus bracket on stern.
100 amp alternator.
Small propeller diameter.

I can see this for a go fast planning hull but not a liveaboard trawler. As mentioned, the propeller size would be totally wrong for a displacement hull. Taking a current trawler hull design wouldn't work do to the tremendous weight shift astern. Also, the depth of the average transom (as a single engine application) wouldn't work without a bracket (moving the weight further out). Then factor in the 300 HP, as being too much (for a single application) until you exceed 50 to 60'. At that length the risk factor for dunking the engine in heavy seas becomes very real. Lastly, a 100 amp alternator for a trawler with a house bank is a joke at best.

Ted

All that is required is that you bastardize the term "Trawler" even further. Think seaworthy, salty looking more or less house boat type underwater configuration. Or, Aixopar on steroids.
I certainly will get better mileage than a gas boat. That is where the new boat market is heading.
Think new slow as 10 knots, not 8. People buying old boats are the only ones that care about efficiency and mileage. Many buy old trawlers that can't afford the 3mpg figure.

 

[O C Diver]

Think new slow as 10 knots, not 8. People buying old boats are the only ones that care about efficiency and mileage. Many buy old trawlers that can't afford the 3mpg figure.

Unfortunately cruising boats (trawlers) are no longer built for the top 25%, but the top 5%. Building boats to cruise at 1 GPM isn't a winning strategy.

Ted