A cut above5/27/15
The company’s entire range of marine leisure engines is currently certified for US EPA Tier 3, as well as for EU RCD Stage 1, and already today meets the stringent RCD Stage 2 emission limits — well ahead of 2016 EU legislation. “We are meeting the world’s most rigorous emissions requirements in advance to serve our customers in the best way,” says Tom Tveitan, manager of laws and regulations for Volvo Penta.
But whenever an engine is built to satisfy the requirements of a stringent piece of emissions legislation, its fuel efficiency rarely improves. In fact, it often decreases drastically when emissions improvements are made.
Engineering adjustments can go some of the way toward regaining ground in fuel efficiency. Volvo Penta makes engine improvements — for example, using a twin-turbo solution combined with an increase of fuel injection pressure — that combat a reduction in fuel efficiency to some extent. The biggest gains in fuel efficiency, however, are made with Volvo Penta’s complete driveline — including the engine, propellers, transmission, controls and the EVC (electronic vessel control system) with throttle and steering. Other features, such as the Glass Cockpit, joystick steering, Dynamic Positioning, and autopilot also play a role. The complete system, which is included with both Volvo Penta IPS and sterndrive systems, improves fuel efficiency by 20 to 30% over a traditional inboard shaft engine (at speeds of no more than 31 knots). Volvo Penta is currently one of the few engine companies to supply a complete driveline to OEMs.
“To achieve maximum fuel efficiency, the entire driveline package needs to be developed at the same time, by the same company – you can’t just randomly drop components into the driveline and expect it to behave with the same kind of efficiency as a tailor-made system,” says Fredrik Celander, Volvo Penta product planning manager. “The harmony of the engine, driveline and controls has a positive effect on performance, handling and acceleration.”
In addition to the customized driveline, Volvo Penta’s duoprop propeller system, almost entirely unique on the market, also promotes greater fuel efficiency. Where counterforces exerted on single propellers can cause a boat to move sideways, the duoprop’s second propeller counteracts rotating water flow and allows the boat to move in a more efficient straight line. A single propeller also has to be up to 40% larger and situated further down beneath the boat. That requires a larger boat body — which creates more drag. With a duoprop system, the boat can also travel as slowly as 18 knots and still be on plane — which gives less resistance and uses less fuel. And because the propeller is straight, not facing down in the water, the boat’s bow is not pressed downward, for improved performance.
More power, more room
The primary advantage of the Volvo Penta IPS and system for end users is clear: a significant savings in fuel efficiency. For boat builders, this is also a distinct advantage. As fuel efficiency increases, engines can be downsized with no impact on performance. A smaller engine and engine room can create more space in a boat — and sometimes dramatically so: a 50-foot boat installed with a powerful but more compact Volvo Penta IPS system can often provide the same amount of accommodation space as a 60-foot boat.