Will Dynamic Stability System (DSS) revolutionize sailing?


In one of my many sailing magazines I found a picture in the summer of 2008 that electrified me and was immediately understood: Someone apparently had the idea instead of generating stability with (a lot of) lead in the keel, to use a lateral (laterally protruding) wing or foil to generate lift downwind of the boat and use this as righting moment (RM). 

A retractable foil, used only when righting momentum was required, was a proposition that intrigued me and I was keen to find out more about. I was excited because I hoped that a boat with two fundamentally different characteristics was within reach:

For light winds there is no need for an RM. What is important is a boat that is as light as possible with minimal drag and a lot of sail area. The foil disappears into the boat or is pushed to windward - into the air.

And for more wind an equally light boat, which thanks to the foil would still be stable downwind. The more speed the boat makes, the more RM the foil delivers, to an extent that cannot be achieved with conventional ballast keels.

Admittedly - I could have come up with this basically simple idea myself. But I was soon to learn that only the basic idea is simple, while the rest is highly complex.

"Dynamic Stability System" or "DSS" for short promises nothing other than "stability when you need it".

Thanks to the internet it didn't take me long to find the inventor and developer of DSS. His name is Hugh Welbourn, a British yacht designer with an America's Cup past, a huge network and the corresponding know-how.

Statistically we sailed our regattas in the summer half year to 80% in the range under 7kts wind speed. So for the most part, stability is the last thing you need. But because there were still the remaining 20% with more wind, the foil would be our insurance and our "turbo".

As a curious and communicative person, I shared my discovery with some sailing colleagues and friends to get to know their opinion. To my surprise (I was probably also a bit naive), I met with a majority of disinterest or even rejection. However, the negative reactions did not unsettle me but rather motivated me to develop a sport boat with this facility. This was all the easier for me as one of my best friends was just as fascinated by the idea as I was. Max Schmid (then owner and managing director of Bucher&Schmid in Lucerne) became my partner and together we founded QuantBoats. Today Max and I share the daily work.

In August 2008 Hugh invited us to join him in testing a 27' long DSS test carrier near Gibraltar. We flew there and experienced DSS live for the first time. The approach and implementation convinced us because we saw that it worked. We never imagined that we would change the sailing world with it in one fell swoop. The risk of failure was given and we calculated this possibility.

The adventure could begin. A few thousand e-mails and almost three years later, we launched the Quant28 in Lucerne and won the first regatta on the very first weekend - "out of the box", so to speak. However, it was a rocky road until it was so far.

The DSS story began long before we came into contact with the DSS 27' in Gibraltar. The first test with a converted Australian sports boat called "Boatspeed 23" took place in Brisbane (AUS) - in secrecy and about two years before we met Hugh. 

A foil was glued to the boat on one side only and connected to one of the outriggers (trampoline) on the boat in order to better transfer the forces developed by the foil to the boat. 

Already at the first test, the crew could experience what happens in reality: In a steady thermal of 10 to 11 kts, the boat made 9 kts of speed on the beat without the foil, with the crew weight all upwind. After the turn - the foil was now working downwind of the boat - and with identical wind conditions, the speed increased to 12 kts and the crew moved to the middle of the boat. 

After a while the wind increased briefly to about 14 - 15kts. The boat accelerated and the GPS showed 16kts for a short time. On this occasion the foil said goodbye - it just snapped off. The people on the support boat could observe that the hull of the boat was lifted completely out of the water at the last moment before the loss of the foil, so that one could look under the boat for a moment.

This sketch got the ball rolling. It shows a detail of the patent specification for DSS. I found it in a sailing magazine and it put me on the "right track" so to speak.
"Our" designer Hugh Welbourn. He started in 2000 with the development of Dynamic Stability Systems (DSS) and approached over the years step by step the goal of practical application on (almost) any size boat.
How DSS works: The boat is straightened by the buoyancy of the wing (foil) in the water and pushed down by the crew weight upwind as before. The faster you sail, the more the boat straightens up, because the foil generates more buoyancy with more speed.
The 27ft test carrier we sailed near Gibraltar in August 2008, at full speed in very strong winds. Between the mast and the crew you can see the foil, which temporarily "pierces" the water surface.
Max Schmid - my founding partner of QuantBoats AG. Max and I run the company today as managing partners - together with a (silent) third partner.
Shortly after the turn of the millennium, a foil was fitted to this Australian sports boat of the "Boatspeed 23" class - but only on one side - in order to experience the effect of the foil 1:1 during initial tests. By tacking or gybing, it was easy to see how the boat behaved with and without the foils.
A picture from an early story on DSS in the racing bible "Seahorse international Sailing". Here you can see the oversized foil very well.
We are looking forward to your questions

The topic "Foils" is still very new for many - we are happy to share our knowledge and experience with you.