Technology
The best of everything
When Spirit Yachts and Ben Ainslie’s BAR Technologies set out to create a wooden foiling motor launch, they choseWest System and Pro-Set epoxies
Wood is not a material that’s typically associated with the very latest technologies. Yet the Spirit/ BAR 35ft electric foiling motor yacht is proof that timeless natural materials can be the perfect choice for bleeding-edge projects when it is combined with appropriate resin and reinforcing systems. An ethos that's always driven
Spirit Yachts is one of innovation. The Spirit/BAR foiler is a collaboration of like-minded thinking that combines founder Sean McMillan’s design and styling flair with the yard’s outstanding constructional skills, the expertise in high-speed foiling craft at Ben Ainslie’s BAR Technologies and a visionary, receptive owner. ‘The design brief was for a
classically styled powerboat with a clear-coated hardwood finish and aesthetics that paid homage to the Gold Cup racers of the early 1900s,’ says Spirit Yachts’managing director Karen Underwood. This is, however, a subtle deception as the boat lifts onto its foils at a speed of only 14kts. This is a critical aspect in creating
an electric yacht with a long range, as resistance drops so much once foiling that power consumption falls well below that of displacement
62 SEAHORSE
vessels that can only proceed at very modest speeds. Nevertheless, this commission required a step change in design and engineering to create a boat that looks right on her moorings and at displacement speeds, while also having the right underwater shape for ultra-efficient foiling. An additional complexity is that the foils retract to reduce draught to only 0.75m (2.6in) which gives flexibility to access shallow berths and small harbours. BAR Technologies brought its America's Cup design and simulation skills to the project, helping to create optimised shapes below the waterline, with low-riding foiling technology employed to minimise resistance and improve ride comfort. The result is a 35ft electric boat with an impressive 100-mile range at 22kts and a top speed of 30kts, despite having a battery bank of a relatively modest size. This compares with the 25-70-mile range at five knots which to date has been typical for electric motor vessels of similar length. The foiler’s unique styling includes immaculate timber topsides along with a flexible deck layout that allows a six-seat open cockpit to be quickly
Above: with true classic styling and a spectacular clear-coated sipo wood finish, the Spirit/BAR foiler looks like a vintage Gold Cup racer until it lifts above the waves
converted into a two-seater spider configuration. Epoxy strip-planked construction
has long been recognised as an affordable, lightweight and very stiff option and the hull of this 35ft boat weighs just 596kg. It's amethod that has roots in the pioneering development and information that Gougeon Brothers gifted to every yacht designer and builder in the formofWest Systemepoxy products and literature. It was refined in the late 1980s by Grimsby (UK)-based boatbuilders Farrow and Chambers, who developed a loose-fitting tongue and groove profile thatminimises time needed to plank up a boat and gives optimal space for the glue that holds the planks together. Two thinner double diagonal veneers, also epoxy glued, contribute hugely to the overall stiffness of the structure. If lightweight, rot resistant
timbers such as cedar or Douglas fir are used, the resulting structure has an excellent strength to weight ratio as well as enviable longevity – these are boats with an inherent ability to last for 100 years. The hull is then sheathed in glass and epoxy, creating a layer with excellent resistance to point impacts and thus
CARLO BORLENGHI
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