Large Boats with Outboards

"...looking for a new larger boat and like the idea of outboards."

Why?

It's difficult to replicate power of up to, say, twin 1200-hp diesels with (mostly gas) outboards. Marine diesel usually less expensive, with usually better burn rate, than marine gas. 1000 gallons of diesel less flammable than 1000 gallons of gas. Et cetera...

-Chris

Are you interested in a boat that can go fast, or that can handle rough seas?
There are good reasons why outboards are getting increasingly popular, but seaworthiness ain't one of them.
When the going gets tough, it's as deep in the water as possible (hence one can be even better than two) and well under the bottom of your boat, not astern and possibly hanging in the air every other wave, that you want your propeller(s) to stay.

With the recent rise of big HP outboards, there are several new express boat, day boat and mid-range cat offerings entering the market. Most are sub 50-feet. There are many benefits to outboards but big boats still need ballast.

I'd just add that there is also a need for torque driven thrust for any vessel of size headed for open water.

Rite now, That big Merc V12 is having problems.
Great idea, just lots (LOTS) of problems.
Once these issues are resolved, It may turn into a good power package and the weight to horsepower ratio will be supper impressive on the stern, just not today.

In the future, that big lower end and mid section will have a diesel engine on top. I am looking forward to see that.
Sadly, these packages (gas or diesel) will be super expensive.

IMO; For cost, investment returns and cruising (fast or slow) nothing will beat diesel inboards.

(LOTS) of moving parts.

Haven't been paying strict attention, but seems to me diesel prices we were seeing as we moved the boat south last month were always at least $1/gallon lower than gas...

-Chris

Paid below $3 last week in Florida off a truck. Of course, gas is tumbling down as well when the state isn't pushing cigarette taxes on petrol...

Sold the boat with outboards. No more NON freshwater cooled engines for me.

And big diesel outboards could easily be designed to heat exchange through a closed loop...and that would be an interesting development.

That would only add even more weight to an elevated level. Once had a go fast with a pair of inboards I religiously flushed. Long story short, had several cooling passages clog with salt resulting in loss of a chunk of a piston. Before repowering my last outboard boat, one of the mid areas where cooling water flowed in a Yamaha developed a hole despite always flushing.

Why can’t the heat exchange be remote and on board the vessel just like the fuel tank?

Better yet move the entire engine into a low area of the boat to also put an end to the fish blocking "wall" and help with stability.

I have witnessed outboard power heads with attempts of coolant/cooling years ago. OMC SeaDrive was a great platform for this enhancement. Back then, it was counter productive for cost reduced HP on your transom.
Now days, there is no such thing as a cost reduced outboard. Now days, Darn things should already be coolant/cooled for the price.

First guess, I fear the diesel outboards are raw water cooled also.
I would hope soon the mfgs fix this.

If you remember, Bayliner tried something they called a "L" Drive (now I'm showing my age). Outboard power-head inside the hull confines that allowed a belt driven alternator, power steering and optional FWC.
Below the power-head, outside the hull, like a pod, was the trim-able/tilt-able, lower drive unit. A sail drive on good steroids/drugs. Great idea, no market or technology to keep it working correctly.
Merc shut it down quickly before they killed Force Outboards.

Later but still years ago; I remember when SlyRay made boats with outboards but covered them with a big hood that made the boat resemble stern-drives.