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New sterndrive control system unveiled

The Axius system is among a host of new products from Cummins MerCruiser Diesel

The Axius system is among a host of new products from Cummins MerCruiser Diesel

I’m certain that by now you’ve read a few articles regarding the pod drive systems that are in the process of revolutionizing marine propulsion. Both the Volvo Inboard Propulsion System and the Cummins MerCruiser Diesel Zeus system provide easy, low-speed maneuvering and enhanced vessel control in close quarters and when docking through the use of a joystick that integrates control of the engines, transmission and steering.

These systems were designed primarily for boats around 35 feet and larger. For those of us with smaller boats, CMD has incorporated similar vessel control technology in a more familiar configuration.

I attended the CMD Expo in Charleston, S.C., in August and had an opportunity to operate boats equipped with several different propulsion systems, as well as the Zeus pod drives. These systems provided new and different themes based on familiar propulsion platforms, and give an insight into what lies ahead as a result of some innovative thinking on the part of CMD.

Among the boats I tested was a 33-foot twin-sterndrive cruiser equipped with a pair of 320-hp QSD4.2 CMD diesels and the new Axius sterndrive control system (formally referred to as Apollo). Axius is based on technology that was developed for Zeus, but rather than using pod drives mounted in tunnels, Axius controls twin independently articulating MerCruiser Bravo Three sterndrives powered by the compact QSD diesels.

Axius was developed by the MerCruiser division of Mercury Marine and incorporates its SmartCraft Digital Throttle & Shift, along with the SmartCraft Joystick Docking System. It is designed for sterndrive boats from 28 to 38 feet and doesn’t require special hull modifications. For those of you already considering the retrofitting possibilities, Axius does require a spacing of 37.5 inches on center to allow for drive articulation, which is 30 degrees out. (Zeus drives pivot outboard up to 45 degrees.) It is compatible with any Bravo Three sterndrive and all D series engines, according to the company.

Like Zeus, Axius has to be experienced to fully appreciate the level of control afforded by independently articulating drives. The system is operated through the SmartCraft joystick, which eliminates the need for bow and stern thrusters. The Axius sterndrives provide a great deal more lateral control than conventional sterndrives, allowing the boat to move sideways, at an angle or in a circle using the joystick. The SmartCraft joystick provides intuitive vessel control, making docking much less intimidating.

Controlling low-speed maneuvering also is easier and smoother with Axius. As you manipulate the joystick in any direction, the clutches apply thrust smoothly to the props, blending thrust and directional control without the harshness often associated with conventional sterndrive shifting. Once your low-speed maneuvering is complete, you can release the joystick to resume vessel control with the more conventional SmartCraft Digital Throttle & Shift, making use of the variable assist power steering and optional autopilot system. In this mode of operation, the drives work together, as you would expect from a conventional sterndrive system, but aren’t physically connected to each other.

The Axius-equipped boat was impressive to operate in both joystick and DTS modes. Plans are for an official introduction at the Miami International Boat Show in February, with limited production in 2008 and full production in 2009. I would look for additional features to be added, such as Skyhook station-keeping and automatic vessel trim, by the time Axius hits full production. The system was recognized by the National Marine Manufacturers Association with an innovation award at the International Boatbuilders’ Exhibition and Conference in October.

Another interesting test boat was a 24-foot center console powered by a jackshaft sterndrive. This type of installation is similar to a traditional “close coupled” sterndrive configuration, but the engine is mounted farther forward and is connected to the drive by a driveshaft, or jackshaft. The boat I tested was powered by a 230-hp QSD2.8 diesel mounted beneath the center console, leaving a clear transom (great for fishing) while maintaining normal deck height without requiring an engine box.

With the combination of the jackshaft setup and an efficient diesel, you can expect gains in range, fuel efficiency and reliability, and with the center of gravity placed nearly amidships, rather than close to the transom, the effects of wind and waves change dramatically. The boat was a pleasure to operate. Overall performance was as anticipated — good acceleration and well-balanced handling — but the smoothness and quietness of the engine was a surprise. If I were in the market for a new center console, the diesel/jackshaft installation would be high on my priority list.

CMD also is making strides in its engine offerings. Salt water can take a toll on marine engines and drives, and CMD has developed the SeaCore system for improved corrosion resistance. The SeaCore system uses industrial hardcoat anodizing, a closed cooling system and extensive use of stainless steel. The hardcoat anodizing is applied to all aluminum drive and transom surfaces that are exposed to seawater, including water and exhaust passages, creating an abrasion-resistant surface. The closed cooling system seals the engine from salt water and includes freshwater flushing ports. The SeaCore system also provides MerCathode active corrosion protection. CMD provides a two-year mechanical and four-year corrosion warranty with the SeaCore system.

CMD’s line of Quantum engines continues to grow with the introduction of the QSD2.0, QSD2.8 and QSD4.2 diesels. All feature a common rail fuel system, reduced noise and vibration, and meet Tier 2 emission standards, while providing increased fuel economy and cruising power, according to the manufacturer. The QSD2.0 is a 4-cylinder engine with four valves per cylinder. It’s turbocharged and seawater aftercooled, with ratings up to 170 hp at 4,000 rpm when used in sterndrive applications, and 150 hp with inboard propulsion. It is compatible with Alpha and Bravo drives in addition to the TechnoDrive inboard transmission. The QSD2.8 is a 4-cylinder engine with two valves per cylinder. Turbocharged and seawater aftercooled, it’s rated for 230 hp at 3,800 rpm in both sterndrive and inboard applications. The QSD4.2 is a 6-cylinder (two valves per cylinder) turbocharged, seawater aftercooled diesel rated at 350 hp at 3,800 rpm for both sterndrive and inboard applications.

Cummins MerCruiser Diesel is constantly upgrading its existing products in addition to introducing new ideas. There was a time when choosing a boat was the tough part, and you accepted whatever propulsion package came with it. Those days are gone. In today’s market, with the variety of propulsion options available, I would likely select the general style of boat, choose the propulsion system that best fit my needs, and then shop for the particular boat to accommodate that propulsion system.

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