Preface: I DO Know what a "Hydro-Foil" is and how it works. Just watched the video again. The Foil Sailer seems to have a "String.. OR.. Cord" thingy trailing from under the bow with a weight at the end...bouncing off the waves. WHAT is it's function....??
I consider myself an EXPERT on sailing..... over 40 years experience. Other than an understanding of the "HYDRO-FOIL" concept..I have NO IDEA what is going on here....
NB