When we did our ditching training in the SVC10, we were afterwards shown a film of a 10 foot SVC10 model, specially built to simulate a ditching. Every time it was catapulted into the tank, the model`s nose area underwent violent pitching. The boffins calculated that those G forces would have killed the cockpit crew in the event of a real ditching.
I hope those boffins did their calculations based on dynamic similarity and not just scale, else the results would have been way out.... it's not an easy science, energy absorption and instantaneous accelerations, very dependent upon hard to model specifics. Today I imagine, it would all be done using finite element analysis...