The Swedish Coast Guard recently equipped a high-speed Cobra 35 patrol boat with Volvo Penta’s new D6-350 DPR in a twin-engine installation. The boat is normally fitted with two gasoline-driven 420 hp V8 engines. The purpose of the installation is to compare the performance and fuel efficiency of modern diesel technology with gasoline engines.
Equipped with the new diesel engines, the boat can reach a top speed of approximately 52 knots, barely 4 knots less than with gasoline engines. Most significantly, fuel efficiency is improved substantially.
“At the Cobra’s cruising speed of around 30 knots the diesel engines use 42 percent less fuel than the gasoline engines. This will result in significant cost savings for our activities in the long term,” says Jonas Gustavsson, a Marine Surveyor with the Swedish Coast Guard.
Similar results were measured across the entire speed range – fuel consumption was significantly lower for the D6-350 compared with the gasoline engines. The lower fuel consumption gives the patrol boats a greater radius of action.
Powerful acceleration with turbo and new drive
The new D6-350 DPR is equipped with a mechanical compressor that drives up the torque directly from low rpms and produces a highly powerful acceleration.
“When accelerating from a standstill to maximum speed, the diesels are in fact slightly better than the V8s, due largely to the compressor but also because the power transfer to the water is better,” says Jonas Gustavsson.
The D6-350 DPR engine is equipped with Volvo Penta’s new DPR drive, which has been developed specifically for speeds between 47 and 60 knots. The drive is identical to the DP version but has a smaller lower housing that is optimized for high speeds and stainless-steel propellers. The propellers generate responsive handling characteristics even at low speeds since the degree of cavitation is low.
“The maneuvering characteristic during a sharp turn are significantly better with the DPR drive since the engine maintains its engine speed throughout the turn,” says Jonas Gustavsson.
With its electronic controls and a new type of power steering, the D6-350 DPR is easy to maneuver even at low speeds.” We also felt that the drive line’s higher torque and more efficient power transfer produced increased maneuverability,” concluded Jonas Gustavsson, who also emphasized that the more than doubled service intervals is a further benefit of the new diesel engines.
The Volvo Penta D6-350, with its 350 hp is the world’s most powerful diesel engine with sterndrive, will be introduced during autumn of 2004. The engine has been subjected to demanding and extensive tests in a number of installations on a variety of boats before being launched.
For further information, please contact Ann-Charlotte Emegård, AB Volvo Penta, phone:
+46 31 66 84 18, E-mail: ann-charlotte.emegard@volvo.com
