Now that is bloody unfair... the peak loads come from freak waves, after all, which can't be predicted completely. So you happen to be in one bad spot for 30 seconds, BANG, you pull 4G and lose the race.
Besides, your idea is basically already in use, and it has generated a shitload of bad...
If you use an accumulator (which acts as a spring, I assume), you'd better have a fucking good damper in your hydraulic system. Otherwise - one more vibrating element, possible flutter, all sorts of trouble. Perhaps that's the reason why they don't do this?
Maybe not full advantage, but they use it. They have some valve in the hydraulics that opens when the pressure in the cylinder gets too high, so that the keel drops a little on heavy impacts (I remember Bouwe Bekking mentions it somewhere). That limits the peak loads on the rams, by the way (for...
Well, say a boat sails 15 days with a wave every 10 seconds (seems reasonable from the AA vids). That gives 130.000 cycles, which is indeed very low for steel. But it is not impossibly low if someone screwed up... so the fatigue may be from wave impact after all.
Well, I haven't crunched the numbers, but could cavitation be causing the humming? Or some other flow phenomenon, so not an actual vibration of the keel?
Also, I remember Bruce reporting a humming noise from his keel in the Vendee. Does any of the OP folks know if this has been solved?