Boating: Revolution in the making

The Swedish giant Volvo Penta has long been at the leading edge of marine power technology.

Now, by turning the propellers around, it has taken another huge step forward.

The company calls the discovery IPS, which stands for Inboard Propulsion System. Introduced to the world's marine media in Spain late last year it created quite a stir, as things truly revolutionary tend to do.

Now it is about to do the same here.

IPS uses forward facing, contra-rotating propellers, two per unit, in a steerable drive mounted through the boat's hull.

The props pull, rather than push the boat through the water.

"Conventional inboard installations were at a dead end," says Lennart Arvidsson, technical project leader of the IPS project. "It was impossible to squeeze much more out of the technology, so our team got creative.

"Forward-facing propellers are logical, it's just that no one has taken this approach before in the recreational sector of the industry.

"Because the propellers are mounted at the forward end of the propulsion unit they can function in undisturbed water and thus achieve maximum efficiency.

"The propeller backlash is exactly parallel with the bottom of the boat, which means all the power developed drives the boat forward.

"Efficiency is further enhanced by the twin-prop technology with counter-rotating propellers, since rotation losses are cancelled out."

This means greatly improved efficiency, especially at speeds above 30 knots where shaft drives require more horsepower for ever-decreasing gains in speed. At 38 knots Volvo claims 38 per cent better efficiency for IPS over shaft drives.

The company says the system is setting new levels in fuel economy, performance, safety, comfort and simplicity of handling. There are two systems, IPS 400 and IPS 500 and both are suitable for boats ranging in size from 12m to 15m.

With the 400, the propulsion unit is mated to a 310hp DC-310. The 500 is combined with the 370hp DC-370. Exhaust emissions are extremely low and will meet the requirements due to be introduced in the European Union and the United States in 2006-07.

Volvo is offering these two models exclusively, but expects to add IPS at both ends of the range.

At the upper end, the system can be extended to accommodate Volvo's D12 engines and 700-plus horsepower for boats up to 20m.

Twin installation means each engine is connected to its own propulsion unit, which is steerable and functions like a rudder. Because the propulsion units turn, the propeller thrust is aimed in the desired direction, making for better manoeuvring.

Says Arvidsson: "All boat owners want simple, safe and intuitive driving and the best way to achieve this is through steerable propulsion units. But we did not stop there.

"By controlling the steering electronically we have improved both performance and operating safety."

The system, from steering unit to propulsion units, is electronically controlled and integrated with Volvo Penta's EVC electronic platform. This links each unit to a steering gear powered by an electric motor. The system processes the driver's steering-wheel movements and instantly converts them into steering movements of the propulsion units.

THE company says a key safety feature of the IPS system is that it is designed to minimise the damage caused by running aground.

The propulsion unit is built to withstand low-speed groundings, such as in harbours. Under severe stress - if the boat runs aground or hits an object in the water at planing speed - the propulsion unit is designed to break loose at pre-determined break points, thus protecting the hull from damage and reducing the risk of leakage.

"We spent thousands of hours testing in every conceivable situation in an effort to create problems and ensure our safety functions were effective," says Arvidsson.

The IPS system will be featured on the Volvo stand at the Auckland International Boat Show at Viaduct Harbour from March 10 to 14. A Genesis 400 Targa fitted with the IPS 400 will be on the marina in front of the Loaded Hog.