Dario's Lab

Stability Principles

Time to answer some questions about stability in pitch.  Over the past few months of testing we have found some very interesting things worth sharing.   Stability as an Alternative to Active Management   Without going into the maths, stability in pitch has a strict definition in aircraft theory and is a requirement for what […]

FAQ: Optimum Altitude

Q: “You seem to be just ‘skimming’ above the surface. Why not fly higher?” A: Altitude control in the current (initial) foil concept is supposed to come from the change in foil curvature just below the hull exit point. As the boat rises, the radius of the part of the foil immediately under the water […]


We tested over the weekend with reduced horizontal surface area on the rudders and the results were interesting though more work still lies ahead. Stability is unaffected but the boat is more responsive to changes in longitudinal trim. In the following sequences Tom Stuchbery is deliberately ‘provoking’ the boat with aggressive steering inputs to get […]

More FAQs

This is the second post in response to questions we are receiving frequently, mostly in connection with design choices on Paradox and how they may compare to developments seen elsewhere. I have added ‘FAQ’ as a label so in future these posts can be filtered out by those (fellow sailing nerds) who are interested… Why […]

S Foils FAQ: Why the Top Bend?

The bottom inflection on the foils for Paradox is there to give stability in heave (controlling ride height). This solution is unique to our A Cat and other Martin Fischer designs such as the GC32 and Flying Phantom.The upper inflection is a way to adjust overall dihedral angle. It has also been seen on the ETNZ […]