At the Düsseldorf boat show earlier this year, RS Electric, a sister company to RS Sailing, a U.K. builder of dinghies, beach catamarans, and small keelboats (RS Aero, RS Feva, RS 2000), introduced the Pulse58, a new rigid-hull inflatable with some unusual features. With Hypalon tubes, a large cockpit with nonskid surfaces, saddle seats, and a tow post aft, the boat fits right into the fleet of coach boats buzzing around at every major regatta. A closer look reveals the innovations in this 5.62m (18‘5“) RIB: an electric rim drive, developed by RAD Propulsion, a U.K. start-up; and a dual-tunnel hull (aka M-hull) built from recyclable flax and basalt fibers, post-consumer polyethylene (PET), and resins with more than 20% bio content.
A Different Drive
Hubless electric rim propellers are used as thrusters on large yachts or commercial vessels. This drive reverses the propeller blades, keeping the thick, strong side on the outside, while the thin, pointy ends, which normally would flex, stay near the center, thus reducing cavitation and the attendant inefficiencies. Also, in a boat with a rim drive it’s safer to maneuver around people in the water (i.e., during rescues). The drive, called e-30 (for 30 kW), uses belts to transmit power from twin motors to the hub drive. Based on automotive technology, an electronic management system controls all aspects of drive, motors, and battery condition, as well as the tilt mechanism that retracts the drive into the transom in shallow water.
Electric power is from a Hyperdrive Gen4 14-cell modular lithium-ion battery pack, with 51.8 nominal voltage and 130-amp continuous discharge current, installed in a structural compartment under the cockpit floors. In its press materials, RS Electric claims a range of “at least 35 nautical miles at its maximum speed (>20 knots), so it can be expected to last for a day’s use under normal RIB usage and distances.”
RAD Propulsion was co-founded by Daniel Hook and Richard Daltry in 2019. The two naval architects formerly owned and operated ASV Global, a company specializing in electrically powered autonomous surface vessels.
The company is also working on smaller drive models (i.e., for kayaks and stand-up paddleboards) and aims to supply packaged solutions to OEMs. Those include the propulsion unit, steering, navigation, and an electronic control system, with an ID tag to customize access and user privileges (like on a shared computer). It’s a data-centric approach that relies on permanent connectivity to the cloud via wireless transmission. RAD says it plans to remain “battery agnostic,” because the technology moves fast and is dominated by big automotive players, who are driving the market.
The Pulse58 Pushes Sustainability
The firm’s joint project with RS has integrated electric propulsion with the custom hullform of the Pulse58—a long waterline and two tunnels that run parallel to the keel for its entire length to reduce drag, thus promising better performance and range. Core materials of the structural parts are wood and recyclable PET core (manufactured from post-consumer packaging waste). RS says this closed-cell foam has limited resin and water absorption and does not promote corrosion or suffer degradation over time. In an effort to create a more sustainable product that lends itself to recycling at the end of its service life, RS employs a combination of Biota Flax 200 g/m2 2×2 twill and enriched basalt fibers that “use low-twist technology to provide a combination of sustainability, performance, and processability.” Also, the company says that the custom infusion epoxy from Pro-Set has 26% bio content.
The price for the Pulse58 as announced was €99,950 (about $109,000) for a boat with the “fully specified standard inventory including 57-kWh [battery] capacity, electronic touchscreen display, Tech Grip cockpit nonslip, and five years of software updates.”
RS Sailing, 19 Premier Way, Abbey Park, Romsey, Hampshire SO51 9DQ, U.K., tel. +44 (0) 1794 526760.
RAD Propulsion Ltd, Merlin House, 4 Meteor Way, Lee on the Solent, Hampshire, PO13 9FU, U.K., tel. +44 (0) 23 9387 0380.