clear, its not a catapult. the mast broke just above the boom. that use to happen mainly when the boomhead is over tie on the mast. maybe bjorn's caddy sanches knows more about it.
what is more important if alberto and ross are not in this lucky (or professional) position above and behind bjorn could happen a tragedy, if one of them hit bjorn with the board or fin. in this reaction time impossible to change direction or stop.
fortunately did not happened...
here comes the helmet question, what was obligated to use only in super x.