Foiling is becoming all the rage among boating enthusiasts the world over, and the commercial potential of foiling is just beginning to be realised, a potential innovative Swedish boatbuilding and technology company Candela is already exploring with some of its larger models.
The Candela 7, though, is designed more for recreational boating and was in some respects the development platform for the company – the 7.5m C7 has now been superseded by a new, larger, faster, and even more efficient C8 model, one of which is headed to our shores soon.
The owner of the only Candela C7 in New Zealand is Wanaka’s Kostya Marchenko, who also represents the Candela brand here. Kostya is a self-confessed foiling nut who enjoys a range of foiling watersports – and Wanaka is an ideal watersports venue, particularly in the summer months. He’s also a huge advocate for electric propulsion – he drives a Tesla – which explains his enthusiasm for the Candela brand. With masses of torque, the Tesla easily tows the C7.
The Candela C7 is an unusual looking boat, certainly on the trailer, which was custom built in Sweden. It’s a braked tandem-axle design with a combination of wheels and rollers. The central double row of rollers pivots for easy launch and retrieval and an electric winch does the winding. While the trailer seems quite lightly built, it is certified by NZTA.
One of the keys to the C7’s impressive performance is its light weight. All up, it weighs just 1.4 tonnes, but the hull is just 90kg! The rest of the boat’s mass comprises batteries, the motor, hydraulics, foiling equipment, cooling pumps and electronic and ancillary gear.
The hull is constructed from hand-laid carbon-fibre, as are the hydrofoils, including the outboard T-foil. In ‘flying’ mode, the C7 rides on a single transverse hydrofoil amidships, supported by two uprights that pivot slightly fore and aft at the behest of Candela’s computerised hydraulic active control system, which also twists the foil for finer control. The foil retracts under the hull, the uprights sliding inboard between the seat backs on either side of the boat.
The C7’s computer takes data from a pair of ultrasonic sensors in the bow which assess wave height and wave interval in real time, from gyros, an accelerometer, GPS and a compass. It interprets all the data and uses a clever algorithm to alter the foil’s angle of attack, making continuous adjustments for wind, wave height and load up to 100 times a second. The outboard T-foil is also actively controlled to maintain pitch and stability.
Candela has developed not only the foiling set-up, but also the hydraulic active control system and sophisticated software controlling it, which all work together to achieve and maintain smooth, level flight. It’s a very impressive technology suite.
Conditions on the lake for our afternoon with the Candela C7 started off sunny and calm, if a little nippy, at least for the Aucklanders among us. Kostya launched the boat singlehandedly and brought it alongside the dock so we could board. The electric motor is housed at the top of the outboard leg, rather like a conventional outboard powerhead, but the streamlined leg or skeg is much longer, extending 1.5m underwater. The outboard has three positions: fully tilted for trailering; intermediate for low-speed manoeuvring in shallow water; and fully down for foiling.
Marchenko describes the motor as happy collaboration: the electric motor itself, its control system, and the battery are all by German marine electric propulsion leader Torqeedo, while the housing, actuation system, skeg and rear foil are Candela. The Torqeedo 400KWh Deep Blue battery is essentially the same as is used in BMW electric vehicles – in the Candela, it’s water-cooled and comes with an eight-year warranty.
The boat looks much more conventional in the water. It’s a bowrider design with relatively low freeboard. The hull forward of the foil has a wave-breaking v-section, but behind the transverse foil the boat is virtually flat-bottomed for ease of planing. We were grateful for the optional bimini top and side windows, which protected us from the chilly slipstream.
The windscreen is acrylic (glass in the C8) with a walkthrough window and door panel to the bow. The interior is stylish, in a Scandi-chic sort of way, but hardly luxurious. Sculpted back-to-back seats, plus a pair of seats across the transom and seats in the bow, are upholstered in attractive light-coloured fabric, but to save weight the padding is minimal.
There’s storage in the under-seat transom lockers, but these also house fuse panels, fire extinguisher and charging cables, with more in the glovebox and under the bow seats. The C7 gets teak floors and coamings, as well as cleats and fender clips down both sides, otherwise, the interior and exterior is simple and clean.
The main feature at the helm is a 12-inch touch-screen display. It provides fingertip control of the boat’s systems and displays operational modes, battery status, power consumption per mile, percentage of engine power used, range and navigational data. Charts are by Navionics. A second panel with buttons and a rotary dial provides manual vessel control.
With everyone aboard, Marchenko moved us off the dock into deeper water before fully lowering the propulsion unit and hydrofoil. Then, with a clear 300m run in front of us, he pushed the throttle forward and the C7 accelerated, quickly reaching lift-off speed, which is somewhere between 15 and 18 knots, depending on load.
With four adults aboard it was closer to 18 knots, but once the magic number was reached, the C7 rose clear of the water to fly 100cm above the surface of the lake. As soon as the boat began foiling, power use dropped dramatically, from 100% of available engine power just prior to lift off, to 20% or less when foiling. The noise levels also drop away, though there was some mechanical noise from the motor and hydraulic chattering from the active control system as it went about its work, but in general the foiling experience was both serene and surreal.
We flew off down the lake, riding flat and level, banking gently into turns, and enjoying the stunning scenery. In standard default mode the boat banks 8° in turns, which keeps the g-forces on the passengers under control; in sport mode, banking angle increases to 12°. In reality, the foiling turning circle is large, so turns are gentle affairs – just allow enough sea room. Turn too sharply and the computer will take over and land the vessel.
There’s really nothing to driving the boat – the computer takes care of all the mechanical aspects, leaving you to steer and manipulate the ‘throttle’ which regulates electric power to the motor. The electric motor has a nominal power output of 85hp, which doesn’t seem a lot for a 7.5m boat. But this is no ordinary boat and foiling is so efficient that 85hp provides ample performance.
Our top speed was 29 knots using 60% of available engine power, while a comfortable 20- to 22-knot cruise speed delivers the best ‘economy’ and range. Above 25 knots, progress becomes noisier due to foil cavitation, noticeably so above 27 knots. There’s no wake to speak of, regardless of speed.
Range/endurance is pretty decent, too: 50 miles (80km) in ideal conditions, but more realistically, says Marchenko, 40 miles with two people and the canopy. Boating on Lake Wanaka with his family of four, Marchenko regularly travels 35 miles, depending on wind and wave conditions. To minimise the chance of inadvertently emptying the battery, the C7 reserves the last few miles of range, which must be completed at displacement speed.
All in all, I found the Candela C7 an interesting and surprisingly easy to operate vessel, especially considering its ground-breaking technology. But in some respects, and despite its not inconsiderable price, it still felt a little like a work in progress, which in many respects it is. During our time with the C7 the flight height fluctuated a little unnervingly at times, especially in choppier water, and the noise of the hydraulics became more noticeable the harder they had to work. Nor was the electric motor especially quiet, though much quieter than a conventional outboard. Candela has sold 35 of the handmade C7 model worldwide, paving the way for its new, bigger C8, which, says Marchenko, has addressed these minor concerns and made many more improvements. The C8 will be the first real production model for the company.
By design, the Candela C7 will only foil when the wave height is less than 1.1 metres. As the wave height limit approaches, the computer and the hydraulic control system must work progressively harder to maintain stable flight, as we experienced on our return journey.
By the time we’d finished enjoying Glendhu Bay, conditions on the main lake had deteriorated considerably. At the widest part where the wind funnels down three different arms, we encountered confused metre-plus waves. The C7’s hull struck a few wave tops in quick succession before the computer said “Enough!” and cut the power, bringing the boat off the foils for a computer-controlled splash-down. With hindsight we should have worn the seatbelts, which I’m guessing are fitted to keep occupants in their seats when this happens!
A couple of subsequent attempts to maintain foiling failed, the computer automatically reducing power when it was unable to compensate for the boat’s pitching and rolling. The safety protocol works as designed.
We finished the journey at displacement speed, but with ample battery capacity in reserve – at five knots, power consumption is the same as at 20 knots, around one kilowatt-hour per nautical mile.
After the exhilaration of flying, the last few miles tootling along at seven knots made for a slightly disappointing end to a fun day aboard such a technologically advanced boat, which – while clearly not suitable for choppy conditions – still feels like the future of powerboating. Electric is coming, so is foiling. Bring on the C8.
