The Outboard Expert: Yamaha F350 — Meet the New Boss

New horsepower leader enters outboard arena.

21st February 2007.
By Charles Plueddeman

hown in triplet configuration on this Grady White 360, the F350 is the most powerful stock outboard currently on the market.

hown in triplet configuration on this Grady White 360, the F350 is the most powerful stock outboard currently on the market.

With a dramatic flash of strobe lights and a clap of electronic thunder, Yamaha previewed its new mega-outboard, the 350-hp F350, at the Miami International Boat Show on February 15. The motor won’t be available for water testing until May, but Yamaha (www.yamaha-motor.com) revealed specification and technical details at Miami.

Reported dry weight for the Yamaha F350 is 804 pounds, or about 212 pounds more than the 3.4-liter V6 Yamaha F250.

Reported dry weight for the Yamaha F350 is 804 pounds, or about 212 pounds more than the 3.4-liter V6 Yamaha F250.

Here are the basics. The motor is a double overhead-cam 60-degree V8, displacing 5330cc, or 325 cubic inches. Reported dry weight is 804 pounds, or about 212 pounds more than the 3.4-liter V6 Yamaha F250. The motor features variable valve timing, ionic combustion sensors, a new anti-corrosion system, massive forged motor mounts and transom bracket, heavy-duty gears and drive shaft made of hardened steel, a special series of propellers, and a new air-intake labyrinth designed to keep water intrusion to a minimum. It is also the first Yamaha outboard to feature a digital drive-by-wire throttle and shift control. Yamaha says the motor’s astounding weight is a result of its desire to make the F350 extremely durable, and reliable enough to take far off-shore. Yamaha has simply made every component stout enough to handle the motor’s rated thrust as it presses against the transom of a pretty big boat.

If final development stays on schedule, Yamaha should be shipping the F350 to boat builders this summer, and it will be available through dealers for re-power later in the year.

The motor is a double overhead-cam 60-degree V8, displacing 5330cc, or 325 cubic inches. and features variable valve timing, ionic combustion sensors,

The motor is a double overhead-cam 60-degree V8, displacing 5330cc, or 325 cubic inches. and features variable valve timing, ionic combustion sensors,

Yamaha Marine Group President Phil Dyskow envisions this new motor hanging on the transoms of boats weighing 20,000 pounds and more, and noted that sales of outboard-powered boats over 26 feet are up 30 percent in the past four years.

“The F350 will allow our boat builder partners to make outboard-powered boats that could reach 40 feet or more in length,” said Dyskow. “At the same time, it’s a great power solution for a lot of existing boats.”

Yamaha says that it worked closely with a number of its “partner” boat builders — including Grady-White, Edgewater, and Pursuit — as it finished development of the motor. More than a year ago, Dyskow used the Grady-White 360 Express (www.gradywhite.com) as an example of a boat that would be perfect for his big outboard. With an LOA of more than 39 feet and a beam of 13 feet 2 inches, the 360 Express has a dry weight of 15,000 pounds without engines. In the past, a boat of this size would be powered by inboards. Instead, Grady design the 360 Express for outboard power, and so far it’s been rigged with triple Yamaha F250 motors.

“Why hang outboards on a boat like the Grady 360?,” said Dyskow. “Because when you move the power outside of the boat, you gain performance and a lot of space. Builders will now be free to add a larger midcabin, for example. Twin outboards will probably cost less than twin diesel inboards, they will be faster, and they will be easier to service.”

And with the introduction of the F350, the Grady 360 can run with twin outboards, rather than triples, and have motors designed specifically to move the mass of a heavy boat.

Yamaha also expects to do a brisk business in the repower market, replacing 250-hp outboards that delivered marginal power and performance on heavy boats. According to Yamaha, the F350 produces 40 percent more thrust than the F250. The F350 is designed to mount on the same center spacing as Yamaha F250 motors, and the brackets use the same bolt holes as those motors, although the F350 takes two more bolts, for a total of six fasteners on each bracket. Yamaha has also been consulting with Teleflex to make sure there are steering cable components available to handle the weight and power of the F350.

Some more details on the engine: It will be built on a dedicated assembly line in a new facility in Japan, so Dyskow does not think there will be any limits on production capacity, a problem that plagued Yamaha when its first big four-stroke outboards were introduced. The powerhead was designed from scratch for this application and has more than 600 new parts, but Dyskow points out that its cylinder dimensions are the same as those of the four-cylinder F150, so in simple terms Yamaha started by mating two F150s at the hip.

The new Yamaha Saltwater Series XL props have a diameter of more than 16 inches, and will be offered from 17- to 25-inch pitch.

The new Yamaha Saltwater Series XL props have a diameter of more than 16 inches, and will be offered from 17- to 25-inch pitch.

Last year Dyskow told me he thought the biggest engineering challenge in developing the new motor would be in the design of the prop and gearcase. To work well in its intended application, the F350 needs a lot of prop blade area. The new Yamaha Saltwater Series XL props have a diameter of more than 16 inches, and will be offered from 17- to 25-inch pitch. This motor has a larger-diameter prop shaft, so only the new prop series will fit on the F350, and these props also won’t fit on any other Yamaha models. I assume every other component up the drive line is equally over-sized and machined from stout materials.

The new Command Link Digital Electronic Control will throttle triple engines with twin levers, has automatic engine synchronization, a trolling feature that fine-tunes engine speed in 50-rpm increments, and has a plug-and-play capability for easy rigging of a second helm station.

At Miami, Yamaha said the F350 will have a suggested list price of $26,245 ($27,375 for counter-rotation), which really seems quite reasonable. Consider that a current Yamaha F250 has a list price of $20,490, and that a triple-engine set-up will cost about $62,000, compared to $53,620 for twin F350s. We hope Yamaha lets us make that performance comparison in May.

Yamaha F350 Specifications

Block configuration V8 60 degree
Displacement 5.3 Liter (5330 cc) (325 ci)
Prop shaft horsepower 350 @ 5500 rpm
Cylinder heads DOHC/32 valve with Variable Camshaft Timing
Compression 9.6:1
Full Throttle RPM range 5000 ? 6000
Fuel induction Sequential multi-point Electronic Fuel Injection
Fuel type Regular Unleaded (Minimum Pump Octane 89)
Alternator Output 50A (40A @ 1000rpm)
Gear ratio 1.73:1
Controls Command Link – Digital Electronic Controls
Weight 25″ shaft / 804 lbs
C.A.R.B. 3 Star
MSRP $26,245

Editor’s Note: Charlie Plueddeman is the editor at large for Boating, the nation’s largest boating magazine.


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Charles Plueddeman is Boats.com's outboard, trailer, and PWC expert. He is a former editor at Boating Magazine and contributor to many national publications since 1986.

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