Grab the mast when it's rigged up, then move it into the position where it's touching the nose of the board. Where the boom touches the nose, then that's what's going to be smashed in a catapult. You need to pad whatever touches the nose, be that boom or mast.
That said, even with a boom bra I still managed to completely and utterly smash the nose of my board almost clean off, then after chopping the nose off and putting loads of fibreglass on it's sustained zero damage there after 5 months solid sailing (although I'm much better at avoiding catapults now as well...). I used to have to patch it up every second session, don't need to worry about it now. Thanks decrepit for the repair advice

When going broad, make sure your back foot is well into the strap, straight front leg, bent back leg, and remember YOU are the master of your craft, not some freak gust. If you feel yourself going, muscle that mast back towards you and don't let yourself be pulled forwards.