Actually, not much happens.

I just had my home-build Timber epoxy Taipan and I the rush to get through the surf I forget the lift the luff daggerboard. So I sailed right up the beach with it fully extended. Nothing happened, I need to look really hard to see which board was pulled across the sand for meters and meters. We did jump off as soon as well noticed something was wrong and the water was shallow enough. But that was really rather late. I think I only stepped of when the water was only 4 inches deep. The boat was actually standing on its board under on angle of about 15 degrees. Looked a bit funny, but even more stupid.

Of course I didn't hit the beach full speed but still I had some good velocity as I was trying to stay ahead of the breaking waves.

Kick-up daggerboards are more complex to make and are not really efficient in the way of performance. Also when well made the daggerboard can take some abuse. Therefor it is just simpler to not make them kick-up.

If you hit something with a daggerboard you either feel a thump go through the boat (jellyfish, plastic bag etc) or you slow down very rapidly and push your bows down. I haven't hit any rocks or 2x4 's yet so can't tell.

Wouter