“When the world’s largest small-sailboat manufacturer decided to expand to electric boats, they chose a rim motor coupled with a RIB –  Rigid Inflatable Boat – as the best package to introduce the world to their new company.

RS Sailing made big news at BOOT Dusseldorf this January when it announced a new sister company – RS Electric Boats – devoted to boats powered by electrons instead of wind. Because of their reputation and status in the industry they knew they had to get the first boat exactly right and spent two years developing the world’s first production RIB with a fully integrated electric drive.

Most electrified RIBs are standard RIBs with an electric outboard replacing a fossil fuel motor on the transom. Of course there is absolutely nothing wrong with that – the workboat introduced by NaviWatt last year and the new Pure Watercraft outboard and Highfield RIB combination for the recreational market are both great electric options.

RS decided to do it differently, though, perhaps because their deep involvement in sailboat racing led them to look at the needs and desires of local yacht and sailing clubs for quiet, odourless coach boats to be used at regattas. Their response is the Pulse 58, which addresses those needs but also has lots of features that any boat owner can enjoy.

Rim motor is ideal for coach boat use

One of the key elements of the Pulse 58 as a response to coach boat usage is the rim motor and system from RAD Propulsion. A rim motor is exactly what the name suggests – its propeller blades are attached to, and driven from, the circular rim of the motor, instead of the usual set up of propellers being attached to a central hub.

rim motor showing how there is no internal hub and the propeller blades are attached to the outer rimThe rim motor is seen more commonly on large vessels where they are used as thrusters to aid in steering, or on underwater remote controlled ‘drones’. They are characteristically quieter than propeller/hub motors, and they are also less likely to get entangled with fishing line or other items – like the lines of sailboats that might be in a regatta. For this reason, and also the safety of not having open propeller blades in crowded waters, the RAD rim makes a lot of sense for RS Electric.

The RAD team’s experience in rim motors comes from their background in robotics and naval architecture, and they worked closely with the RS Sailing team on the Pulse 58. One of the features RS knew they wanted was for the motor to be retractable, for times when the Pulse would be required to venture into shallow water. It’s a fairly simple proposition with an outboard, but more complicated with an integrated motor!

Developing that ability was part of the whole process of integrating boat and motor, which touched on almost every aspect of the boat design, right down to the basics of hull shape and dimensions.

rim motor on the Pulse 58 is powered by 8 battery packs seen in the case in the hull of the boatThe tunnel hull design formed by the RIB’s tubes coupled with a long waterline give decreased low speed drag to work with the instant torque of the motor. A structurally integrated case sits deep in the hull, holding the 57 kWh battery bank and providing a low centre of gravity for stability and comfort.

Regatta and training boat use can be extremely demanding – and unpredictable – so the  Pulse’s range is at least 35 nautical miles at its maximum speed (>20knots).

The electric tilt mechanism for the retractable motor is part of the overall system controlling and monitoring the motor, power reserve, range data and plotting/navigation features. One of the important items for regatta usage is the geofencing capabilities to control security and safe use.

On the Pulse58 all of these operations are viewed and controlled through a Raymarine touch screen, but the RADLink electronics system has been designed with a proprietary transmitter that can feed data to a Garmin display or many other mainstream electronics systems.”

Read the rest of the article here