Driving Higher Performance

By Craig Ritchie | April 29, 2025

Although they deliver higher speeds, lower fuel consumption and greater overall efficiency than competing powertrains, surface drives have never achieved significant adoption in the recreational boat market. But could a revolutionary new design change that?

Surface drives have long been popular among manufacturers of offshore racing boats and, to a lesser degree, among luxury performance yacht builders like Hinckley, Otam, Pershing and Mangusta. Yet despite offering a number of appealing advantages over other propulsion systems, surface drives have never managed to achieve mainstream popularity. Today, a New Zealand manufacturer aims to change that with a novel approach to surface drive design.

Surface drives are most closely associated with American inventor Howard Arneson, who in the late 1970s developed the steerable, trimmable surface drive that bears his name. A passionate fan of speed boats, in 1977 Arneson purchased a 40ft Arena Craft that was equipped with twin fixed-shaft surface drives. While impressed with the vessel’s speed, Arneson was unhappy with the boat’s handling. He subsequently developed a surface drive concept of his own which used an articulated shaft with multiple hydraulic arms to provide steering and trim control. In 1983, a 38ft Cougar Cat race boat rigged with Arneson’s new surface drives went on to win nine successive races and the offshore racing world championships, rocketing the surface drive to prominence in performance boating circles.

Surface drives achieve their high performance through the use of surface-piercing propellers, which reduce underwater drag by as much as 50% compared to sterndrives or conventional shafts. With the propeller blades and possibly a protective skeg representing the only running gear in contact with the water when underway, surface drives deliver significantly faster acceleration and higher top speeds than traditional drives or shafts, along with reduced vibration and reduced cavitation due to the propeller being vented to surface atmospheric pressure.

But for all their advantages, legacy surface drive platforms come with trade-offs. Underway, they can be louder than vessels with fully submerged running gear, and their semi-exposed props can throw a substantial rooster tail of water behind the boat, which some boaters may find unattractive. They’re also known for being less maneuverable at lower speeds, and more difficult to operate in reverse. Worse still, the arrangement of having the drives extend well beyond the transom on the water surface can leave the running gear vulnerable to impact damage when vessels need to maneuver in confined spaced like marinas.

A Better Way

Leigh Michau, CEO at Aukland-based Q-Marine International Ltd, set out to redesign the surface drive in order to address those shortcomings while retaining the concept’s many benefits. The result is the Q-SPD surface drive, which uses a clean-sheet design approach that he says significantly improves maneuverability and low speed performance, while offering greater durability and less frequent maintenance.

“Most of the surface drives that have been on the market for the past 40 years are developments of the original Arneson units,” he says. “And they work well enough, but they all share the same basic constraints which are inherent in the basic design. The Q-SPD drive consciously moves away from that traditional approach and leverages advantages in modern materials and more up-to-date engineering approaches to escape the challenges that are associated with legacy designs.”

Utilising a lightweight composite construction, Michau says the Q-SPD drive offers a more compact footprint with all hydraulic cylinders, lines and other essential mechanicals housed within the vessel. The result, he says, is not just a neater transom but greater reliability and lower upkeep than previous surface drive platforms. “Having hydraulics and bearings and tubes full of oil exposed to the water just is not terribly sensible,” he says. “I wanted to have a clean stern without all these hoses, so I decided all that stuff had to go inside the boat. Everything outside the boat had to be water lubricated, not oil lubricated.”

The result was a more streamlined and compact installation that could more easily replace a sterndrive, he says. The shroud-like housing is further said to contribute to quieter operation, while fitting easily beneath a closed swim platform with no need for ventilation grills and pipes.

“The first thing I wanted to do with the surface drive was to take the rudder off the back of it,” explains Michau. “A lot of legacy drives have the rudder positioned behind the propeller, where it is extremely vulnerable to damage. So, I thought let’s do something about that. I began wondering if there was some way to hang a rudder beside the propeller, which evolved into using two rudders which would act as a sort of shroud. That immediately provided an opportunity to leverage different dynamics, so that reverse thrust is going to be far more effective.”

The drive concept evolved to utilise a monocoque composite main structure, moulded using resin infusion of Eglass and carbonfibre fabrics in an epoxy matrix that is temperature cured for maximum strength. The resulting unit is significantly shorter than legacy surface drives, while weighing up to 50% less with its non-corrosive, composite construction.