You’d have to be holed up in a yurt in New Mexico not to notice the trend toward larger outboards powering bigger and bigger boats over the past decade. Walk any boat show dock and you’re guaranteed to see five Seven Marine 627s hanging off the back of some 53-foot center console. There’s even a 65-foot “center console” on the market—it seems the “console” is as long as most Grady-Whites from just a decade ago.

Outboard-powered super yachts? Time will tell.

Outboard-powered super yachts? Time will tell.

With smooth, powerful gasoline outboards available up to 627 hp apiece and diesel outboards entering the market, the trend isn’t going to stop any time soon. (Assuming we can get enough propeller blade area behind each engine to transmit power to the water.) So, where is this all going?

627 hp x 5 = 3,135 hp. That’s within 65 horses of what’s installed in each new Hatteras 98 motoryacht. Today we have the horsepower (albeit gasoline) to replace inboards in a 100-footer with outboards. Since Volvo Penta now owns Seven Marine, I’d be surprised if they’re not already thinking about morphing their torquey diesel IPS system into an outboard configuration. Tomorrow we’ll have diesel “outboard pods” to supply a combined 3,000 hp to any kind of boat we can dream up.

Think about it: a large motoryacht with no engine room to speak of. No main engines inside the hull. No gearboxes, long heavy shafts or stuffing boxes. No exhaust system with huge, heavy mufflers and outlets running 25 feet to the transom. No main engine intakes or seacocks to spring leaks in the bilge. No engine room ventilation fans. We’d need only a relatively small pump room for the leftover equipment like generators, gyro, air-conditioning compressors, batteries and bilge pumps.

This will change boat design in the years to come. It will simplify the manufacturing process, since propulsion, steering and exhaust are all just bolted onto the transom near the end of the build schedule. It will make maintenance easier, as there will be fewer systems inside the yacht, just like today’s typical center console. Liquid loads will need to be positioned where they mitigate the heavy engine weights hanging off the transom, but we already do that on today’s big center consoles.

The creature comforts normally found on a 125-footer will fit nicely into a 100-foot outboard-diesel-pod-powered motor-yacht with no engine room. You want a huge side-opening tender -garage and spa? Check. A full-beam VIP stateroom? Check. How about a two-deck atrium leading to side-opening hullside doors, creating a beach club amidships? All this and more could be possible in a motoryacht with no engine room.

With three, four or five diesel-outboard-pods instead of two huge engines buried inside the boat, long-term maintenance could become easier, since overhauls could be performed “on the bench” instead of inside the vessel by simply unbolting the engine in question.

All of this is well and good for newly-designed and built boats. But since our fiberglass boats don’t just turn to dust like most old wooden boats, there may come a day when the outboard manufacturers look toward the refit market as well. Do you have an old Hatteras 53 motoryacht ready for a re-power? Three or four of today’s diesel outboards might do the trick and open up space for a gyro stabilizer, a fourth stateroom and a midships beach club in the process.

So while diesel outboards are in their infancy, you can bet they will become more plentiful and more powerful in the next several years. This will surely influence boat design and help create a new generation of vessels unlike any available today.

And don’t forget those little electric-powered outboards. They’re sure to grow as well. After all, even an outboard-powered yurt has got to be more fun than a stationary one.

This article originally appeared in the Summer 2020 issue of Power & Motoryacht magazine.

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