The star of the show-and-tell was the revolutionary Volvo IPS (Inboard Propulsion System), a through-hull propulsion developed by Volvo Penta about five years ago. Unique to Penta, the drive system puts the propeller ahead of the drive unit, which is located through the hull instead of behind as in a conventional inboard engine/outdrive or using a long shaft with P-brackets and rudder.
IPS mounts propellers on horizontal shafts, parallel to the hull. IPS has a host of advantages: It puts the puller propellers – contra-rotating on Volvo Pentas – in water undisturbed by the gear casing. And because they are parallel to the hull instead of being at an angle dictated by the 10-15 degree down angle in a conventional shaft configuration, there is no tendency to lift the rear of the hull and thus force down the nose. This means less water friction, less energy wasted lifting the boat and less drag on the hull. It also allows for a little additional optimization of the hull shape reducing or eliminating the “rocker” to compensate for shaft angularity.
