NOT ONLY IPS: RIO YACHTS REDISCOVERS THE SHAFT DRIVE.

Rio Yachts and shaft drive: what are the advantages? Rio Yachts and shaft drive: the reasoning behind a unique choice.

Despite the European market being largely dominated by IPS and outboard-powered boats, shaft drive still offers countless and unique advantages. This is clearly demonstrated by Rio Yachts‘ decision to produce a series of models that, at the owner’s discretion, can be equipped with this transmission system.

It’s a choice that very few shipyards offer, driven by the strong demand from enthusiasts of shaft drive propulsion. And I’m not just talking about the flagship of the range, the Sport Coupé 58, but also the Le Mans and Daytona lines, where the 45- and 50-foot models can now be fitted with shaft drive. In this case, owners primarily opt for two engine choices: Yanmar and Cummins, both offering 550 hp, which easily push these boats beyond 35 knots. For the Sport Coupé 58, however, the preferred choice is Volvo Penta, with the 1,000 hp D13 model delivering truly impressive performance for the flagship.

To support this statement, a premise is necessary: the maneuverability gap that once existed in tight waters is now a thing of the past. Shaft drive—just like outboards and even surface thrusters—now allows for the same precise maneuvers that have long been a hallmark of IPS systems.

Thanks to interfaces with bow thrusters, the action of the propellers, and the adoption of joysticks and advanced electronics, all these transmission systems can now perform lateral and diagonal movements or hold position with pinpoint accuracy, regardless of the chosen setup.

Well, the first one is pretty obvious—it generates significantly less drag. The exposed surface area is much smaller compared to IPS, which, for the same reason, is highly susceptible to marine growth, especially barnacle buildup. Shaft drive, on the other hand, suffers much less from this issue, both because propulsion relies on a single propeller and because IPS units have considerably larger lower units.

The second advantage of shaft drive over IPS is undoubtedly its impact on the boat’s trim while underway.

Shaft drive PUSHES the boat forward, while IPS, with its forward-facing propellers, PULLS it toward the bow. As is well known, this type of propulsion—despite its other advantages—tends to lift the bow and lower the stern of yachts equipped with it.

This results in a less-than-ideal cruising trim, whereas with shaft drive, this effect is either absent or significantly reduced. As a result, shaft-driven boats maintain a much more level planing attitude, offering clear advantages—first and foremost, better onboard comfort and improved forward visibility.

Additionally, IPS-equipped boats are generally less responsive to tight turns. In contrast, shaft drive, combined with rudders, allows for a much tighter turning radius. This translates into more agile handling and a driving experience that better suits sporty boats.

Moreover, when it comes to both purchase and maintenance costs, shaft drive is significantly more affordable. IPS systems not only have a higher upfront cost but also demand much more in terms of maintenance expenses.

The advantages of IPS, on the other hand, are equally well known. They consume about 15–20% less fuel compared to an equivalent engine setup (Volvo to Volvo, for example), thanks to the higher efficiency of their forward-facing propellers. However, this benefit quickly diminishes if the boat isn’t used frequently, as IPS drives are particularly prone to fouling growth.