Sounds like something funny's going on with those rudders. Where are they breaking? And did they both go in the same way?

Sailing with one broken rudder would mean putting more load on the other rudder in order to get the same movement, but even so, I'd expect to have to seriously abuse a rudder to get it to break (short of hitting something, obviously).

Have you checked the rudder rake? If you've got them raked way forward under the boat, that might explain something. Someone on this forum talked of forward rake causing breakages (Rolf, was it you?), but I would have thought you'd have to use ridiculous rake for this to happen.

Paul