Thinking about it - these days when we do go in (f18 and I presume f16 would be similar), usually both of us are thrown clear of the mast and wind up in the water. By far the biggest danger is the back of the daggers if you catch one on the way thru which is nearly a body impact and can hurt no end. You'd need body armour a-la motorcross to protect you from that one.

Foiling boats?? Hmmm - really depends how much faster they are going I suppose. If they are getting 30+ knots then yeah - may need to rethink this helmet thing.