Diesel-electric propulsion: Near-silent operation up to 9.5 knots.
Zero emission hotel mode: No internal combustion engine is required to operate all on-board systems while at anchor.
Shaft alternator power generation: The economical navigation mode, with a single main diesel engine turned on. The two propellers can be powered and generate enough electricity for the entire yacht.
Traditional direct diesel engine propulsion: Ensure ssimplicity and reliability of traditional transmission and guarantees at the same time the traditional fast cruise speed performances of the Yacht.
Booster power mode: maximum performance, top speed increased up to 1.5 knots and faster acceleration using Electrical & Diesel power together.
The Hybrid system is a combination of twin MTU 2,400 hp diesel engines and electric motors added to each propeller shaft, operating in parallel with the MTU diesels.
Despite the massive disparity in the rated power of the diesel engines and electric motors, they deliver roughly the same torque to the propeller shafts - up to a diesel speed of 1000 RPM. As a result, the electric motors can drive this SL 106’ yacht up to 10 knots. When in diesel engine mode, the electric motors can either be used to boost the diesel engines for faster acceleration or can be driven as powerful generators.
The system additionally includes 2 x 250 kW KOHLER permanent magnet DC generators and a 150-kW/h lithium-ion battery pack. The battery pack can deliver power to overnight air-conditioning at anchor without running a generator (one of the key goals of the system).
The electric motors can handle all low-speed propulsion until the battery pack is depleted. This eliminates the most inefficient range of diesel engine operation at the same time as it delivers a remarkably quiet ride (another of the key goals of the system). At 9 knots the range in calm waters is around 10 miles. Once the battery pack is depleted, either the generators kick in, or one of the diesel engines can be engaged driving its electric motor as a generator which powers the second electric motor.
The combined propulsion and electric motor load on the operating diesel engine is sufficient to drive it into a relatively efficient part of its fuel map, resulting in substantial overall fuel savings as compared to the conventional practice of running both diesel engines at light propulsion loads.