MS-Fins Hyper: A high-end fin with air channels – an interview with developer Michael Still

“The better is the enemy of the good” seems to be Michael Still’s motto. The standard “MS-Fins X7” had already impressed our surf testers, but the next generation is already undergoing rigorous testing. We recently had the chance to try out a special prototype: the ‘Hyper’ fin gave the Starboard Futura – which was already highly manoeuvrable with the standard fin – even less drag whilst maintaining the same fin size, whilst also offering a more stable glide. A fin with exhaust vents on the trailing edge, ventilated by ingenious channels running through the fin bolts and the fin blade. The “Hyper” demonstrates technical perfection, combining theoretical and practical know-how from Formula 1.

​In testing, the MS-Fins Hyper offered less drag whilst maintaining a more stable glide.

​How did you come up with the name?

The effort involved was clearly going to be so huge and the idea so crazy that I thought: ‘This will either be absolutely brilliant or an absolute disaster.’

Was there an initial catalyst for the idea?

As is always the case, I found myself thinking about what could be done even better. In the process, I came across a diagram illustrating the drag forces on the airfoil. The airfoil and the surface generate drag, as do the leading edge and the trailing edge. As far as the leading edge, surface and profile are concerned, I believe I’ve found the optimum for myself. The trailing edge, on the other hand, had previously been guided solely by the principle: sharper means less drag – blunter means more drag. Then, in a Lüderitz report, I saw a fin by Erik Beale with a cut-off edge. Whether this is due to cavitation (Ed.: Formation of vapour bubbles and pressure drop) I’m not sure whether it should be ventilated. It looked a bit rough in terms of workmanship, but I found the idea interesting. That’s because a boundary vortex and negative pressure form at the trailing edge of the fin – and that creates drag. I then set about looking to see if there were any working examples in aerodynamics, and found what I was looking for in Formula 1. In 2010, McLaren introduced a system called the F-Duct, in which air was channelled through a driver-controlled vent to the low-pressure side of the rear wing. This created the suction cup effect (Ed.: Contact pressure) reduces and makes the car faster.

And what is the purpose of the air intake on the fin?

If you eliminate the low-pressure area at the trailing edge by feeding air in to reduce drag, that’s a brilliant idea. And given that drag increases significantly as speed rises, and the low-pressure area draws in more air at higher speeds, the idea should offer advantages at higher speeds.

How does the air get there?

A framework is laminated into the fin as a placeholder; this is then removed once the material has set, forming the air channels (Note: individual pipes and hoses that can be pulled out upwards and backwards). The air ducts consist of vertical tubes running towards the tip of the fin, and channels that connect the tubes horizontally to the air outlets at the trailing edge. Currently, a size 44 slalom fin features four tubes and 14 channels.

That sounds complicated.

Yes, I used to take a lot of stuff to the bulky waste collection too. If something goes wrong, three hours’ work on building the frame and laminating goes down the drain, but the success rate is very good now.

Michi, thank you very much, and here’s to continued success!

​MS Fins: Fin guru Michael Still on the development and secrets of fast fins