Заблудился?

"...The wing has two to three times the power of a soft sail and also offers greater control for its sailors..."

(т.е. не на 20-30% эффективнее, а на 200-300%)

Там же, в коменте, с более понятной метафорой:
"it may look ugly (dependent on the viewers "affiliation") but sure it is fast. Efficiency of a wing sail is two to three times better than that of a regular sail..."