it’s been “flying” as long as I can remember. It’s the distinction between that and floating.

A traditional boat relies on buoyancy to keep it away from the murky depths, while these boats rely on buoyancy only when at rest or going slowly. After that, once the foils take over, they are genuinely flying in that no buoyancy is involved.

But then again, does the word really matter? People refer to “flying” in hot air balloons, too.