Anyone who wants to get out on the water in absolute light winds is faced with the question: "Which is better? A low- or high-aspect foil?" We tried out the two new products, the Ultra Jet 2000 and the Jet HA 1840, as examples.
On land
Manufacturer Naish offers a modular foil concept in which front and back wings of different sizes and models can be combined. The Ultra Jet front wings have a low aspect ratio ("low aspect ratio"), i.e. a comparatively small span in relation to the surface area, and are available in six sizes (850/1050/1250/1650/2000/2450 cm2). On the other hand, there are the stretched high-aspect wings of the Jet HA line, which are available in sizes of 640/840/1040/1240/1440 and 1840 cm2. Regardless of which front wing you choose, the wings are mounted on a 64 centimetre long aluminium fuselage. Naish traditionally uses thinner M6 Torx screws to mount the foil to the board and attach the wings. The components are characterised by a high fitting accuracy, the screws were still tight even after long sessions. The connection between the mast and fuselage is reminiscent of a fin box familiar from windsurfing - here too we had no problems with loose screws, Naish uses thick M8 Torx screws at this point. The mounting plate is additionally secured to the mast with a cross bolt to prevent it from shaking loose. If you opt for a "Semi Complete" set consisting of fuselage, front and back wing, you will also receive screws, suitable tools, a bag and cover for the wings.
On the water
We swapped back and forth between the two front wings in different conditions to determine the differences in performance. The prejudice that thicker profiled low-aspect wings such as the Ultra Jet 2000 take off earlier is only partially confirmed. From a physical point of view, this is true insofar as even a lower speed is sufficient to generate enough lift for take-off. In practical tests, however, it is also noticeable that the High-Aspect-Foil offers slightly less drag due to its thinner profile and therefore achieves the necessary (higher) take-off speed with comparable pumping effort. The situation is different after take-off: Both foils are wonderfully stable around the transverse axis ("nose up, nose down") and easy to ride in the water. However, the Jet HA with its mighty 112 mm span has a slight tendency to roll around the longitudinal axis. In order to keep the foil stable on course, it needs to be evenly edged and even in manoeuvres you have to consistently load the edge in order to always remain in control of the situation. Generally speaking, it helps to surf the Jet HA 1840 with footstraps, as this gives you better control over the foil. The Ultra Jet 2000 is noticeably easier to control in this respect - with its smaller span of 100 centimetres, it is stable and has less life of its own, the radii can be varied more easily in manoeuvres and the foil can be controlled more precisely.
The GPS measurement to determine the top speed was also exciting for us. Due to its thinner profile, the Jet HA 1840 initially feels like it offers less resistance - you think you're faster here than with the Ultra Jet 2000, where the supposed speed limit is more noticeable. However, after a few well-powered runs, a look at the GPS reveals that the actual difference is less than expected: on both test days, we were able to accelerate the Jet HA 1840 to 31.5 km/h with a 5.0 wing, while we reached 30.6 km/h with the Ultra Jet 2000. This shows once again that the top speed potential of foils is not only defined by the aspect ratio, but also depends significantly on the wing size.
Naish Jet HA 1840 & Ultra Jet 2000 Foil - the conclusion
With the Jet HA 1840 and the Ultra Jet 2000, Naish has two wings in its range that also offer very good light wind suitability thanks to their harmonious take-off behaviour. In this size, the Ultra Jet convinced us even more for light wind freeriding, for foil manoeuvres and for the needs of wingfoil beginners, because it is even easier to ride and appears more light-footed in manoeuvres. The Jet HA 1840 is primarily the better choice if downwinders in small wind waves are on the wish list. As expected, the Jet HA offers even better glide due to its larger wingspan.
