Elegant electric boat perfect for remote Maine lake

When a long-time client of Stephens Waring Yacht Design of Belfast, Maine, wanted a boat to maximize enjoyment of a new vacation home on an island in a remote lake, the decision was already made that electric was the key.

Having test-driven traditional ICE-propelled boats and disliking the noise, exhaust, and appearance, the choice was clear for the client that a custom electric powered boat would be the perfect match for the serenity of the pristine lake environment.

Commuter boat, also watersports

It also had to have plenty of utility, though – able to carry several passengers with endurance and reliability, on the 2-mile journey to and from the home dock to the mainland.

On top of that, the client also wanted performance. The boat had to be ready for recreation and fun, including occasional tubing and waterskiing, with a top speed of 25MPH.

The end result is the elegant and stylish Isobel, a 26 footer of cedar and composite with an electric propulsion system by the UK’s RAD Propulsion.

elegant electric boat Isobel seen at the bow

Stephens Waring is a custom naval architecture and engineering firm whose specializes in blending classic sailing yacht design with the latest in materials and technology.

They also do powerboats, and the company is no stranger to electric propulsion. In 2010 they designed Zogo, a 29 foot hybrid diesel/electric-runabout built by French & Webb that features a solar canopy.

All of this has given them a deep appreciation for the efficiencies of how a boat moves through water and their experience was well put to use in designing Isobel.

Light weight wood-composite

With gasoline or diesel powered boats, if you want to go faster or farther, it’s pretty easy – just add a bigger motor or more fuel. Not so with a wind or electric powered boat, especially one that planes. Weight and hull design matter.

electric boat Zogo designed in 2010
Zogo electric-hybrid boat designed by Stephens Waring in 2010

As they note on their website, “For design of any planing watercraft, weight is the enemy of speed and range.The careful use of wood-composite construction for Isobel—cedar-strips sheathed in fibreglass for the hull and a plywood/foam/plywood sandwich for the deck and cockpit sole deliver a light displacement of around 1,300 KG (with two persons aboard), as well as a cost-effective custom build.”

The overall styling of Isobel demonstrates how efficient design is also beautiful. She has a sleek profile with mid-century modern styling that draws inspiration from the elegance of 1950s Rivas. She cuts through the water effortlessly at low speeds, then gets on and holds a plane with equal ease.

A low sheer allows comfortable stepping aboard amidships, the shallow draft makes trailer-launching viable even on a rudimentary ramp, and her stern platform allows for water access and facilitates fun for swimming and skiing.

RAD 40 electric outboard with swivel lower leg

That maximizes the impressive capabilities of the RAD’s 40 kiloWatt / ≈ 55 hp electric outboard that they chose to propel Isobel.

RAD Propulsion came out of the world of building electric motors for autonomous underwater vessels. Their experience in the mechanics of electric propulsion is uparallelled, and when they decided to put it to use on an electric outboard for consumers and OEMs, they took a clean sheet approach to the design.

The first thing they questioned was why tilting up an outboard motor had to take away useful space on the deck of the boat.

So the RAD 40 has a low, compact profile where the outboard remains behind the transom eve when tilted up and doesn’t intrude into the deck area.

The next ‘RADical’ idea was to make the movement of the lower unit, or lower leg, independent from the electric powerhead. It swivels a full 180 degrees while the head stays in place – providing exceptional control and manoeuvrability.

Isobel comes with a RAD 55kWh battery pack that produces 350 volts, supports fast charging via CCS standard system, and can go from 20 percent charge to 80 percent in under an hour. For a truly green, zero-carbon, and economical footprint it can be charged from the island’s off grid solar infrastructure. It takes more time, but who cares when enjoying a cool summer evening on a quiet lake?

See the RAD 40 on the Valkama Picnic cruiser

At full power the system provides a range of 25 miles or about an hour of top performance operation. This equates to half a dozen round-trips to the mainland at top speed, but with most commuter trips moderated to a cruise speed of 12-15 knots, the electric runabout’s range is doubled.

Pete Byford, Chief Technology Officer at RAD, said of the partnership: “Stephens Waring came to us with this project looking for a drive and battery for an electric commuter boat, without compromising on performance, style or ease of operation. We are delighted to partner with them and Isobel is a beautiful boat that the RAD 40 compliments perfectly.”

Elegant electric boat performs equal to ICE

For both S-W and RAD, one of the most exciting things about Isobel is showcasing an electric boat that can perform equal to similar ICE counterparts, but with the added enjoyment of near-silent operation, no noxious fumes, no oil and gas slicks and almost zero maintenance.

Bob Stephens, of Stephens Waring Design, said: “From our first interaction the RAD team have impressed us with their expert engineering knowledge and attention to detail. The RAD 40 with its standout design and superior operating features makes it the ideal choice for the high spec Isobel. We are looking forward to getting testing underway to deliver the finished boat to our customer later this year and hope this will be the first of many projects with RAD.”

RAD Propulsion   Stephens Waring Yacht Design

RAD 40 in Plugboats Marketplace

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