The Loneliest Number
Posted: May 1, 2011
The ZF Pod system is the first ever to allow true joystick control with only one engine.
Most of us are familiar with the Volvo Penta IPS and the MerCruiser Zeus and Axius joystick docking systems. These magic devices allow even rookie drivers to dock and drive larger boats with an extremely short learning curve. They all use multiple pod drives that can articulate independently to vector the thrust around and move the boat in any direction when docking. But ZF Marine, the builder of MerCruiser's pod systems, is going it alone - literally - by creating a monopod that can be used in conjunction with a bow thruster to deliver shockingly similar results to the twin-pod joystick system.
The purpose of this setup is to bring the benefits of pod/joystick docking to the masses, so they can use one engine to power their boats, thus bringing down the price of ownership and the cost of operation. The system was first shown at the 2010 Ft. Lauderdale Boat Show and later at the 2011 Miami Boat Show, and members of the media were given a hands-on opportunity to try the ZF Pod. The first prototype boat we could get our hands on was a 34-foot SeaVee 340i center console.
Running the Numbers
Powering the ZF 2800 Pod with twin counter-rotating props was a 480 hp Cummins MerCruiser 5.9L QSB turbocharged diesel, which was capable of pushing this rig to 38 mph at 3500 rpm. At its best cruise speed of 32 mph, it got better than 2 mpg, which is impressive since it has a deep-V hull with 23.45 degrees of deadrise at the stern. Maneuverability when running with the single pod was fantastic, and because the engine wasn't hanging on the transom, ­balance was excellent.
In Easidock mode, the pod can turn 180 degrees, which is reduced to 30 degrees or less when cruising. Before Easidock is enabled, the ZF 185 AC bow thruster acts like a normal thruster and is independent of the drive system - except that it is reputed to be able to run for an hour straight, which is far longer than anything I've ever tried. Most thrusters seem to sense when you need them most and conk out at the exact wrong time. Another improvement over many thrusters that are all-on or all-off is that the thrust on this system is progressively stronger when you put more pressure on the joystick, giving drivers far better control.
When Easidock is engaged, the thruster and pod work in concert thanks to an onboard computer. Like its twin-pod counterpart, this system pushes the boat in any direction - even sideways or at an oblique angle. Because the bow thruster has the kind of "giddy up" to move a boat sideways against a current, you have to twist the joystick slightly as you push it sideways to track straight. A really handy feature is the iAnchor station-keeping function that keeps you planted in one place without having to work the stick.
The Future of One
So what is the future of this mono-pod system? ZF is a worldwide company with more than 61,000 employees, and it does more than $17 billion in sales per year (about 12.5 billion Euro). It has the ability to make this system available for a wide variety of boats, ranging from gas-powered 20-footers to 60-footers with 1,000 hp diesels. The system is an especially good fit for 27- to 34-foot cruisers, which could really ­benefit from single-engine economy and reduced weight.