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Axius takes the technology down to sterndrives

Axius is a sterndrive control system from MerCruiser that takes advantage of advances in computer and electronic technology developed for the Zeus pod drive system.

Axius is a sterndrive control system from MerCruiser that takes advantage of advances in computer and electronic technology developed for the Zeus pod drive system. Axius sterndrives provide considerable more lateral control than conventional sterndrives, allowing the boat to move sideways, at an angle or rotate within its own length.

Read the other stories in this propulsion package: Dawn of the diesel outboard?   Kicking it up another notch   New outboards at a glance   POD Power

Working through Mercury’s SmartCraft DTS (Digital Throttle and Shift) and its electronic/hydraulic power steering, Axius controls independently articulating MerCruiser Bravo Three sterndrives to provide low-speed joystick docking and maneuvering, making boat handling simple and intuitive.

“Anyone can dock and maneuver a sterndrive boat, where previously it was an intimidating and often-

embarrassing task,” says Rob Noyes, vice president of marketing for Sea Ray Boats, of Knoxville, Tenn.

Designed for twin-engine applications, Axius is a combination of several components that are electrically interconnected to provide almost seamless directional control of the boat, without the use of bow or stern thrusters ( The drives can rotate independently up to 30 degrees outboard (Zeus pod drives rotate up to 45 degrees), allowing the full thrust of the prop to be directed for precise maneuvering. Axius breathes new life into sterndrive systems that appear to have been bypassed in the technology race over the past few years.

“Axius is being installed on boats from 28 feet to 40 feet,” says Noyes. Beyond 40 feet is where conventional inboards and pod drives come into the picture. That seems to cover a lot of ground, providing alternatives for the boater who is looking for a midsize package he can own and operate.

The user control that brings Axius to life is the SmartCraft joystick, which provides intuitive directional and speed control. Like the pod drive systems, Axius needs to be experienced to be truly appreciated. I have operated several early test boats equipped with Axius and can vouch for the manufacturer’s claims. It blends the engine’s thrust and the sterndrive’s directional control without the harshness often associated with more conventional propulsion. Experiencing the simplicity of operation and enhanced overall performance of Axius-powered boats has reopened my eyes to sterndrive boats and their flexibility.

Operation of Axius-controlled boats is intuitive. If you want the boat to go directly to starboard, just push the joystick to the right. If it’s port you want, move it to the left. The joystick allows you to move at an angle, such as forward and to starboard at the same time, by moving the joystick accordingly. Minor midcourse alterations are just as simple.

Axius lets you turn the boat 360 degrees within its own length by simply rotating the joystick knob. The independently articulating drives work to create additional thrust and leverage, thereby spinning the boat in its own length. The more rotation you give to the joystick, the quicker that the boat will turn. The rate or speed of boat movement also is controlled by the joystick. To increase boat speed in a specific direction, just move the joystick a bit further. The boat will follow the joystick, with directional control and thrust proportional to the degree of joystick movement.

When you back off on the control, the boat responds instantly. Parallel docking between other boats is made almost effortless. Just pull up alongside, find the open space and move the joystick directly toward the dock. The boat moves neatly into the vacant space. Any compensation required for the effect of wind and current can easily be handled with slight movements of the control. (The feature-laden Axius Plus, with its auto yaw control, simplifies this even more.) When more finely tuned docking maneuvers are required, such as maneuvering within a slip or confined area, you can select the docking mode, which provides for more-

refined close-quarters operation.

The ease of controlling the boat masks the actual operation of the drives, but there is a lot going on below and behind. While you are effortlessly moving the joystick, the sterndrives are operating independently (without tie bars), steering in different directions while simultaneously applying thrust, often in opposing directions, and seamlessly responding to your joystick input.

Conventional sterndrives require the user to select forward or reverse gears and combine throttle and steering input for each drive — all while trying to determine if the boat is reacting as you anticipated. With Axius, joystick movement is translated into boat movement.

Axius Plus options provide advanced piloting features such as auto heading, which through its integrated electronic compass allows you to lock on to the boat’s heading and maintain that heading, keeping the boat on course through rough seas and windy conditions. It also allows you to alter that course in 10-degree increments.

The advanced auto yaw control, like the auto heading feature, uses the integrated electronic compass to maintain the boat’s heading, which is very useful in docking and close-quarters maneuvering. I found this feature especially helpful when parallel docking in windy conditions with an opposing, swiftly moving current. Yaw control allowed me to concentrate on the boats docked tight in on both ends of ours. It allowed me to minimize one concern and operation from the undocking process.

The Axius system has to be programmed and calibrated by the manufacturer for each specific boat model in which it is installed, because each vessel has its own particular handling and performance characteristics. The joystick controls are designed to function within a limited engine rpm range, depending on the particular boat/engine combination. My test boat was limited to 1,800 rpm. Beyond the preset rpm, or any time that you want to switch to conventional controls, releasing the joystick defaults the vessel systems back to the SmartCraft Digital Throttle and Shift, which then makes use of the variable assist electronic/hydraulic power steering. In this mode of operation, the sterndrives work together as with a conventional system but aren’t physically connected to one another.

Axius is an impressive system that certainly enhances sterndrive performance and handling. Aside from the low-speed maneuvering aspect, MerCruiser reports that when compared with inboard performance, Axius is quicker to get up on plane and will do so at lower speed. It reportedly raises fuel efficiency by more than 30 percent and top speed by 20 to 25 percent, according to the manufacturer. It costs less than pod systems and offers power choices of 260- to 425-hp gasoline engines in addition to the diesel packages.

Even so, you’ll pay more for Axius, as you will with any new technology. Although I have not seen any firm price structure, partially due to the variables in engine, boat and accessory combinations, there will be a premium. But Noyes suggests that if a conventional twin-engine boat will run you around $150,000, it isn’t hard to justify moving up to $165,000 to take advantage of the new technology. Last October, Axius was recognized with an Innovation Award from the National Marine Manufacturers Association and Boating Writers International.

Sea Ray already is delivering Axius-equipped boats to dealers, and Noyes says that “for the new model year, we will have Axius available on every sterndrive boat we build.” In addition, you can expect to see Axius installed on boats from Formula, Rinker, Maxum, Bayliner and Crownline.