Toughest sea you have been to?
I am interested, how much weather can RIBs take?
My personal experience was wind force 7, sea 6 in a tiny (under 5m) Viking 470 GRP with 60hp Yamaha outboard. December. North Sea, MOB SAR situation. The screw got "aired" constantly and it was difficult to even control the boat not to come "sideways" against waves. The boat seemed too heavy and did try not to go on the wave crest, but rather crush through it. Recovering body was successful, but attempt to get back onboard the mother vessel was not at all.
I wonder how other RIBs take on weather. Sure RNLI jumps into the sea also past force 6, do they?