56 Later production vessels will have a new bespoke battery pack. Rated at 63 kWh, the new pack is also smaller and lighter and has both the BMS and the PDU inside it. This will be fitted into a modified hull with a smaller battery compartment, the engineering team says. Also a 400V system, the new battery uses CCS2 charging. Enter the RAD 40 Getting propulsive power into the water is the function of the RAD 40 drive. RS Electric Boats has been working with RAD Propulsion almost since the inception of the Pulse 63’s development. Initially, RAD developed a ‘rim drive’ propulsor for the boat, an idea that the company explored and then shelved as far as this application is concerned. In a rim drive thruster, the blades are mounted on the inner portion of the rim and point towards the centre of the thruster, which has no hub. The rim also forms the rotor of the electric motor that powers the thruster. “It was good and efficient at the low end of the speed range, but didn’t quite have the top-end speed that we needed,” RS Electric Boats’ engineering team explains. The companies then experimented with a number of drive configurations using Mercury stern drives but these also lacked the efficiency necessary to achieve their top speed target with the power available. “We were only getting a top end of 16 or 17 knots.” The Pulse 63s currently in service use these stern drives, but boats are today being delivered with the RAD 40 system, now testing of that system is complete. The RAD 40 was the solution to the challenge of attaining the required speed. Resembling a compact outboard motor, this system packages a RADmanufactured electric motor that drives a custom-designed three-bladed propeller into a compact unit along with electric steering and trim systems. The entirety of that unit remains behind the boat’s transom when tilted up out of the water. At the heart of the tilt system is a pair of hydraulic rams that are fed pressurised oil by an electrically-driven hydraulic pump. The RSE engineering team notes that the RAD 40 is around 50% more efficient than any of the stern drive systems previously tried. “We now get 23 knots out of it on the same power as before,” they say. Weighing 60 kg, the RAD 40 measures 732 mm long, 401 mm wide and either 956 mm or optionally 1106 mm deep. This compact footprint maximises usable space. “It’s neat and doesn’t interfere with the hull too much. We still have a flat area at the back, which you don’t normally get if you’ve got a great big outboard in the way,” they add. Delivering up to 40 kW continuously, the system works more like a podded drive than a conventional outboard motor in that the lower section supporting the propeller is steered while the upper portion (the head unit) remains stationary with respect to the hull in azimuth, although the trim actuators are attached to it. The 300 mm diameter propeller steers through +/- 90°, giving the boat greater lowspeed manoeuvrability than most, even enabling it to spin around within its own length. Both steering and throttle use drive-by-wire control, while the throttle provides responsive forward and reverse control, a neutral safety mechanism and illuminated indications of trim and tilt settings. Drive-by-wire smarts The safety benefits and weight savings enabled by drive-by-wire technology were major factors in the company’s selection of RAD’s technology. In operational terms, some of those safety benefits come from the throttle’s programmability in that the power can be limited for certain users, and calibrated at the owner’s request. From a skipper’s point of view, the smart throttle is quite different from conventional throttles, according to Jon January/February 2024 | E-Mobility Engineering Ready for fast charging, the 400V RAD 40 provides up to 40kW (55 hp) of continuous power, integrating the inverter and motor in a compact housing. Both throttle and steering are drive-by-wire systems (Image courtesy of RAD Propulsion) With +/- 90° deflection, the RAD 40’s steerable leg adds significantly to the Pulse 63’s low speed manoeuvrability, enabling it to turn through 360° in its own length. The tilt system is electro-hydraulic (Image courtesy of RAD Propulsion)
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