Spirit Yachts has less than a month’s work left to finish the hull of its radical new e-foiler before it is moved to BAR Technologies for the foils to be fitted.
Built out of cold-moulded wood with a carbon fibre reinforced shell, the Spirit 35 Foiler combines stunning retro looks and craftsmanship with the very latest electric drive and foiling technology.
The 35ft (10.7m) project is due to be transported to BAR’s Portsmouth facility in May for the final fit-out, including the installation of its cockpit controls, lightweight titanium rudder, retractable foils and electric powertrain.
The details of this are secret but we do know that the take-off speed will be 14 knots with a fast cruise of 20 knots and a top speed of 28 knots. The battery’s running time at 20 knots is predicted to be around five hours, giving a range of 100nm.
The hull’s ring frames and planking are made from Alaskan yellow cedar but the topsides will be skinned with a decorative layer of African sipo finished with a high-gloss lacquer.
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She was drawn by Spirit Yachts’ CEO and chief designer Sean McMillan, who admits to taking his principal inspiration from a slightly smaller twice Gold Cup winning hydroplane of mid-1920s America called Baby Bootlegger, which sported a similar near-plumb bow, long varnished foredeck and a two-seat cockpit.
The latter is also rather reminiscent of a vintage racing car, complete with token fold-down aero-screens and the aerodynamic cowls enhancing gorgeous sloping aft sections. Incidentally those cowls actually hinge up and back to form part of an otherwise concealed and separate guest cockpit behind that will seat up to six.
The Spirit 35 Foiler is a relatively narrow design – the maximum beam is just 7ft 6in (2.3m), which means the length-to-beam ratio is around 4.65.
The actual underwater profile is a modified deep-vee – sharp entry forward, a single step amidships, and flattened off towards the transom. Sean McMillan says below the natural waterline is obviously all about lift, whereas above it is pure stylistic indulgence.
The bare structure of hull and deck are likely to weigh little more than 2,200lbs (1.0 tonne) and ultimately her finished light displacement will be just 5,280lbs (2.4 tonnes).
The retractable foiling control technology is a development of various active systems developed by BAR Technologies over the past decade, including Sir Ben Ainslie’s extreme-foiling America’s Cup racers and the foil-assisted Princess R35 sportsboat, which was unveiled back in autumn 2018.
Fabricated from solid titanium, the Spirit 35 Foiler’s retractable appendages consist of a single T-foil rudder aft, which will control the pitch and yaw, and twin leg and single bar forward, which has wide port and starboard aileron-style trim tabs on its trailing edge that control roll.
Underway the flying attitude will be adjusted automatically via an IMU that takes inputs from various ride sensors. Probably capable of powering over swells of up to 5ft (1.5m) in height, she should register a flying draught of just 2ft (600mm). We’re told she will heel in to the turns reassuringly.
However, with the foils retracted for displacement speed cruising in shoal waters or berthing, the normal draught should be little more than a foot (0.3m). When raised, those three foil legs will stand visibly proud of the superstructure.
Spirit Yachts has never been busier. Beyond this latest motorboat project, it has six other cold-molded sailing yachts at various stages of construction.
It has just completed an electric 44fter, and is also working on an electric 52fter, a 68fter and no fewer than three 72fters in hand.
In response to question regarding the cost of building the Spirit 35 Foiler, BAR Technologies’ CEO John Cooper responded with “reassuring expensive”.