Mercury Marine recently hosted a combination reveal and retirement party for its Verado outboard line. The introduction of its new V10 Verado 350/400 models also marked a farewell for the L6 Verado 350/400, the last descendants of the 2.6-liter supercharged platform that introduced the Verado nameplate 19 years ago. That’s a long run for any powersports product, and in that time, design tools, casting techniques and digital controls have advanced exponentially. Mercury has leveraged this technology, and a deep well of engineering experience, to fill the last gap in its new generation of Verado outboards with these all-new V10 models.
Boats with outboard power have also changed a lot in the past 19 years. Center-console models over 50 feet are now powered by four or five big outboards. Wide-beam day cruisers over 40 feet that previously would have had inboards now have multiple outboards on the transom. While these new Mercury motors will surely find a home on freshwater fishing boats and even pontoons, the primary mission of the V10 350/400 motor is to power this new generation of heavy, multi-engine boats.
The new Verado models have a V10 5.7-liter (349 CID) powerhead that is based on the proven design architecture of the V8 4.6-liter Verado 250/300 models that debuted in 2019. The V8 and V10 share a 92mm bore x 86mm stroke and use the same 64-degree cylinder angle, a commonality that eases manufacturing and supply-chain issues. The V10 configuration also allows Mercury to achieve a desired 5.7-liter displacement while maintaining the narrow profile—and 26-inch center-to-center multi-engine transom spacing—of both the V8 and the old L6 Verado models. This makes installation easier for boatbuilders and simplifies repower applications, as there are no new mounting holes to drill.
All-New Gearcase and Props
What is all-new descends from the powerhead. Mercury employed computational fluid dynamics design tools to create a 6.4-inch diameter gearcase that can accommodate a low, 2.08:1 gear ratio and a propeller up to about 18 inches in diameter. The gearcase is an inch larger than the V8 Verado gearcase, which carries a 1.85:1 ratio.
Paired with that 6.4-inch gearcase is a new line of Revolution X four-blade propellers. With up to about 17-inch diameter and very wide blades, the Revolution X props offer 35 percent to 50 percent more blade area than props popular for the 5.44-inch gearcase. The Revolution X props are available in a pitch range of 18 to 33 inches, compared to 13 to 26 inches for most other Mercury performance props. Only Revolution X props will fit the 1.5-inch tapered prop shaft of the V10 motors.
“The lower gear ratio amplifies engine torque to the prop shaft to help handle all the blade area, and also slows down propeller rotational speed relative to engine speed,” says Mercury Propeller Brand Manager Gary Diehl. “Our engineers love lower prop speed and more diameter because it improves efficiency while maintaining performance. By extending the pitch range to 33 inches, we can still power some pretty fast boats.”
The easy assumption is that a larger gearcase and propeller will increase drag through the water, but Diehl says the deeper prop and gearcase can be mounted higher on the transom. Most builders have moved the V10 motors up one hole, or .75 inches, on the transom bracket.
“A side benefit of our CFD analysis is the ability to shape the new gearcase to generate lift,” said Tim Reid, Mercury’s vice president of product development and engineering. “That helps lift heavier boats on plane, and at speed carries some boats higher in the water to reduce hull drag significantly. Faster boats can raise this gearcase up to a semi-surfacing level. We have tested it at speeds above 90 mph. It holds water well.”
The result is dramatically improved performance—on some boats.
During press sea trials for the new motors at Mercury’s Lake X in Florida, we ran a Boston Whaler 380 Outrage with quad V10 400 outboards to a top speed of 68.5 mph at 6350 rpm with 25-pitch props. Acceleration from 0 to 30 mph was just under eight seconds. A Mercury Boathouse Bulletin test report for the same boat model with quad 2.6-liter Verado 400 motors ran 59.7 mph at 6700 rpm with 18-pitch props and posted an 8.4 second 0-to-3- mph time.
We made a different observation running a Valhalla V-33 powered by twin V10 400 motors. With a top speed of 64.1 mph, the V10-powered boat was only 0.4 mph faster and 1.65 seconds slower to 30 mph than a V-33 powered by 2.6-liter Verado 400 motors. Granted, we ran this boat on a different day under different conditions, but we wondered what gives.
“Prior to the launch, we tested over 40 boat hulls with the new engine, and the performance deltas spanned quite a range, with the Whaler 380 seeing one of the largest improvements,” said Richard Todhunter, Mercury’s director of integration and current product engineering. “The average across all the boats was about 3 to 5 mph improvement in top speed. The variance on the Valhalla was attributed to how efficient the hull already is. The V10 carries load quite well, and you really see that on the heavier, traditional V bottoms.”
Feels Fast
The experience of running a variety of boats powered by the V10 Verados was uniformly outstanding. The motors are counterbalanced to smooth perfection and are eerily quiet—unless the hot rod exhaust tone is engaged electronically. Throttle response is snappy, and if you have spent much time at the helm of a boat powered by the 2.6L Verado, you’ll notice how the V10 feels more athletic. The motor accelerates briskly right to the top of its rpm range. That’s a wide torque band at work. Mercury made every effort to reduce the weight of these motors, even drilling through the center of the crankshaft and camshafts so that “every ounce of metal earns its way onto the engine,” Reid said. With a 25-inch shaft, the V10 Verado has a published dry weight of 709 pounds. That’s 27 pounds more than the 2.6-liter Verado, but 18 pounds less than a Suzuki DF350 and a significant 243 pounds lighter than the V8 Yamaha XTO 425.
The V10 shares many features with the V8 Verado models and other Mercury outboards. The Mercury Advanced Midsection isolates the powerhead vibration from the boat. The Gen 2 DTS digital control incorporates control buttons for standard auto trim. Adaptive Speed Control maintains engine rpm as load changes, when climbing swells, for example.
The motors are compatible with all of the Mercury SmartCraft technologies, VesselView displays and mobile app. The dipstick and oil fill are located under the top cowl service door. The motor makes full power on readily available 87 octane fuel.
Mercury’s electro-hydraulic power steering system is standard with the V10, but we also saw a new electric steering system on many of the boats at the preview event. Electric steering will be an option to boatbuilders beginning in February, and by midsummer it will be standard on all joystick-equipped boats. Mercury says the enhanced response and precision of electric steering is most notable in low-speed joystick maneuvers.
Fathom Ready
To meet the escalating demands of boats rigged with powerful audio, multiple displays, appliances, chillers and stabilizers, the V10 has a new alternator that delivers 150 amps to the boat at just 1500 rpm. That’s more than twice the charging power of the 2.6L Verado models, and 50 amps more than the Yamaha 425 alternator.
The V10 Verado (and soon the V12 Verado 600) will also be available with a new 48-volt alternator designed specifically as a component of the Navico Fathom e-power system, an integrated lithium-ion auxiliary power management system designed to replace an internal combustion generator. It’s been available on some Sea Ray and Boston Whaler models for more than a year; in 2023, Navico will make this system available to boatbuilders outside the Brunswick family. The Fathom house battery banks can be charged by shore power or by the Verado alternators. With a standard 12-volt alternator, this charge rate is so slow as to not be very practical. The new 48-volt alternator changes the game. It offers a rate of charge almost four times faster and enables a new level of integration with the boat. When the boat is running at speed, the batteries can be bypassed and the alternator will directly power accessories through a convertor. The system will also maintain charge in the house batteries, which in turn charge the engine-cranking batteries.
A second charging function, called Power + Mode, turns the V10 Verado motor into a charging station. If the boat is at rest, say at anchor, and the house batteries reach a low charge threshold, the Fathom system will send an alert to the captain on the boat’s multifunction display, or through the Fathom app to a device. The captain may then engage Power + Mode through the touchscreen. In this mode, an outboard with the 48-volt alternator is started and throttled up to no more than 2500 rpm to charge the house batteries.
A number of safety protocols are automatically engaged in Power + Mode. Shifting and steering are electronically locked, for instance. If carbon dioxide is detected in a cabin, the motor is shut down. The cowl must be in place on the motor, and exhaust temperature and water pressure are monitored to ensure that the boat is in the water. The motor has a separate internal hour meter for Power + Mode, so the time recorded at this low rpm is not counted on the motor’s total run time. Mercury says wear on the engine is negligible at this low rpm.
The entire Fathom e-power system is scaled to the load demand of the boat as determined by gear and appliances installed by the builder. This determines both the capacity of the house battery bank and the number of 48-volt alternators added to the system. A quad-engine boat might have one or two outboards equipped with the 48-volt alternator, but could have one on each motor and gain more charging capacity.
One remaining hiccup with Power + Mode is that the outboard needs to run at least 1300 rpm to generate the 48-volt charge. So, a fishing boat trolling for hours at 700 rpm will be charging the house bank at 12 volts rather than 48 volts, perhaps not enough to keep up with load if AC, a stabilizer and other accessories are running. In this situation, you’d need to suspend trolling and drift in Power + Mode, run at speed to charge the house batteries, or get along without your AC.
The Fathom e-power system integrates components from Mercury and Navico Group brands, including Mastervolt, BEP, CZone, Ancor and Blue Sea Systems. All are part of Brunswick.
Color Options
The Verado 350 and 400 models are both available in four lengths—20 inch, 25 inch, 30 inch and 35 inch–to accommodate single and multi-engine applications. Color options include classic phantom black plus three tones of white (pearl fusion, warm fusion and cool fusion). The motors may be further personalized with accent panels in five colors or a customizable, paint-ready option.
The V10 Verado motors are now available to boatbuilders and will reach dealers for retail sale later in 2023. Retail pricing has not been finalized but is expected to be about $40,000 at each horsepower rating.
With the V10 Verado, Mercury completes an all-star team of large outboards designed to power modern boats.
This article was originally published in the February 2023 issue.
