Yes there are, it is not that difficult to make the rear of the daggerboard well much stronger so that the board breaks off rather then split the hulls. But a decent daggerboard design should be able to take some abuse in my opinion.

In the first week of sailing my own F16 (Timber-epoxy) I forgot to lift my luff daggerboard. I always leave that one down (partly) till close to the beach in big surf or strong winds to maintain maximum manouvrebility when out running the breaking waves. Anyway, things were happening and my crew kept talking to me and my mind sort of missed the crucial step of pulling the luff board up fully right before entering the really shallow parts before the beach. We were actually sailing on a reach or broad reach so there was no stopping the boat. Finally I noticed the luff hull lifting and it wasn't the wind. We came to a hold on the beach with the boat standing on its luff daggerboard with me still on it. I had commanded my crew off as soon as I saw that the daggerboard was scraping the ground. I was really fearful that I had just caused major damage in the first week since completing my long awaiting new boat.

Turned out that my daggerboard was just fine, some gelcoat chips were taken of the tip and my hulls were just fine. That was 18 months ago and I haven't had any issues with that hull so far. The hulls seemed to hold up pretty well.

The accident wasn't at full speed but we weren't going slow either.

Since then I've cut some larger jelly fish in halve with my daggers since then. Is not really the same as striking a turtle or a submerged container, but it is good thump anyway.

Like I said, these wells should be able to take some abuse before splitting the hulls. Otherwise a couple of layers of well placed Kevlar (or even glass) will do the strick.

Wouter