Although I am not connected with Hot Lemon, I did
take the pic you refer to on page 16 of Fiblines, and can explain ....
You will notice that the lighthouse bends in the direction of travel in each picture. This happens to all inanimate objects when they are struck by the air pressure wave generated by a high speed Rib such as Hot Lemon which, as we all know, travels at a terrific rate of knots.
The effect that this shockwave has lasts only for a tiny fraction of a second and, although is sometimes captured on film, is rarely visible to the naked eye. For this reason you may not have witnessed such an event.
I understand that the Thrust SSC land speed record holders generated similar air pressure waves when approaching the speed of sound.
To better illustrate the effect I have attached (I hope) another picture taken on the same day. This (I think) is a Fabio Buzzi job and was impressively quick without being too large. I couldn't help noticing a number of well known Rib owners drooling over it, and some were even lucky enough to go for a quick spin.
I would guess that it was travelling half as fast again as Hot Lemon, and you can see what happened to the lighthouse as a result.
Does this answer your question ?