I didn't know that, but the concern remains. To put a frame sticking out below the hull to catch anything that is on the ground seems ludicrous?
Stones, branches, wire etc, but my feeling is
WHY?
Clearly there is ZERO gain by such actions. PLENTY of room above this area so I presume his engineering made it essential?
From a pure engineering point of view (which the chap is clearly gifted and works immensely hard to achieve a beautiful product) - WHY?
NOISE attenuation (hiding the fan) sure isnt the reason
As ever IMHO- (others ARE available)!