Methods for daggerboard crashworthiness

I think you can look to the Van Isle 360 for an answer to that, as it's accumulated at least as many boat-miles over the last 16 years. The only damage I know of from collision with a floating object was in 2011, when the F24C Makika broke their rudder. They were passing a sleeping whale, and the whale woke up and shot into their path.

Deadheads are an everyday hazard when you sail in the Pacific Northwest, but you just keep an eye out for them. Fortunately, they only come out during the day, so you're OK at night. ;-)

 

OK people, going back to the OPs first posting, he has omitted probably THE most compelling reason for a dagger board instead of a pivoting centreboard.
A daggerboard (case for same) has the minimum intrusion into the working cockpit space. Compare the internals of, say, a 5o5 and its pivoting cb and a Cherub (or similar) with a daggerboard. Having owned/sailed both, there is no comparison - I would take the daggerboard anyday - and keep an eye out for thin water.

 

Damn, I thought I was going to be able to edit the first post so I could add things like this and it would all be neat and orderly. Guess there is a timer?

Yes, but that wasn't what he was talking about. He wanted to make the board break away.

 

Looks like there were no damaging impacts in the R2AK. With Tom's comment about the Van Isles race there seems to be 3 possibilities:

1) The lookouts are very good and avoiding action was taken, even at night.
2) The boats are all strong or slow enough for collisions not to be a problem.
3) There is not as much stuff in the PNW water as everyone claims.

If it is #3, maybe I should have chosen different examples.
Transpac (Lending Club missed the record due to hitting stuff from the Japanese tsunami), the Vendee boats after leaving New York, Round The island race where boats regularly hit the sunk steamer off the Needles or the Sydney Hobart where hitting sunfish is a regular occurrence, although not as regular as the owners of some dodgy rudders would have us believe. Or anywhere that the water is shallower than the draft of the boats.

Daggerboards are vulnerable is all these places. It would be good if someone came up with a viable alternative.