A cargo ship's 'WindWing' sails saved it up to 12 tons of fuel per day

So, they are saving 14% and expect to multiply that by 1.5 by having an additional wing. Is there any prospect of getting near 100%? Naively 15 wings would get there. From the image maybe 7 would fit on this ship without a redesign. Once it&#x27;s proven, will it gradually evolve to taking more and more of the energy requirements?<p>Obviously I realize there has to be some fuel in case the vessel would be becalmed, but apart from that, what are the limits?

But does the overall cost of these &#x27;WindWings&#x27; recoup over the lifetime of cargo ship. Including the fact that they can now carry less cargo per trip. And the trip might take longer due to &#x27;route optimizations&#x27;. Insurance is probably also going to be higher now that you have giant sails on top of the ships that makes it both more expensive but also i suspect less safe in rough seas(even when folded).<p>I feel that is the only true measure otherwise cargo ship builders are not inclined to build more of these.

Surprisingly, these appear to be rigid foils (hence WindWing) instead of Flettner rotors.

And who says you can’t reinvent the wheel?

From the article: &quot;Pyxis Ocean reportedly saved an average of 3.3 tons of fuel each day.&quot;

Why don’t sailboats use these?