It seems you can’t read a magazine or attend a boat show lately without stumbling across some futuristic propulsion system that eliminates parts once considered vital to a boat’s anatomy. While traditionalists may grumble about boats that need no rudder or propeller shaft—or steering wheel, in some cases—there are good reasons to take a closer look.

The simple truth for power boaters is that steerable “pod drives” such as the Volvo Penta IPS or the Cummins MerCruiser Diesel Zeus drive represent breakthrough technology in the recreational boating market. At a time when engine makers are making great strides in performance, pod drives represent the leading—some might say the bleeding—edge of propulsion technology.

Incubated for years on commercial vessels, pod drives do away with traditional running gear in favor of propellers mounted on swiveling “pods” that sit below the boat. The props draw power from separate engines, move independent of one another and are capable of maneuvering the boat—or keeping it still—in ways that traditional twin-engine installations cannot duplicate, even with bow and stern thrusters.

While there is still much to be determined as the few thousand “early adaptors” who own these systems put them through their paces, manufacturers claim that these units are more efficient, more maneuverable and offer better fuel economy. They also have some intriguing capabilities, such as station keeping, the ability to keep the boat steady in one place using only the drives.

While critics say these units are expensive, difficult to retrofit and vulnerable to floating debris, converts argue that pod drives will be offered as an option on scores of production boats in coming years. In fact, that list is growing past brands like Sea Ray to include more conservative companies like Silverton—and even Grand Banks.

SEA TRIAL Video by CMD shows Zeus Drive in action.

First to develop and deploy a pod drive for recreational boats was Sweden's Volvo Penta, the same company that invented the sterndrive and the dual contra-rotating prop set. Volvo’s entry is the Inboard Propulsion System (IPS), which sat alone in the market for several years and has been installed on roughly 2,000 boats, according to its manufacturer.

However, it has since been joined by the Zeus system, created by Cummins MerCruiser Diesel, a joint venture of Cummins and the MerCruiser division of Mercury Marine. Zeus is only now being offered for sale, though several boat builders have committed to using it in their new designs beginning in 2008.

The two systems differ in some significant ways—IPS propellers face forward and Zeus props face backward—but both use computers to interpret the helmsman's commands and move the boat appropriately. By using differential thrust and independent pods in a twin installation—the technical term is azimuthing—the computer can move the boat directly sideways or spin on its axis without separate bow or stern thrusters.

You will hear the marketing people from each company argue the merits of forward-facing versus rear-facing props; debate the slightly different exhaust arrangements; and discuss the capabilities of the integrated trim plate that is part of the Zeus pod. But much of this may eventually be lost in the background.

The companies involved in the Pod Wars may not admit it, but the benefits to the boater from either system are similar: significantly enhanced low- and high-speed maneuverability; fuel economy improved on the order of 30 percent; and the advanced capabilities that come with electronically controlled and interfaced systems. Technology add-ons like precision autopilots and speed control also get better when connected to pod drives.