From an E-mail I got, regarding the Jimmy Carter's recent bridge trunk washdown:
"They were making a surface run in heavy weather, driving rain. Three people on the bridge, two lookouts and the OOD. Lookout turns aft and sees something beyond the rudder, which he realizes is the propulsor... definitely not normal. Turns forward to inform the OOD and sees a huge wall of water coming in, over his head, about to crest the bow. Everyone hangs on. The ship is basically submerged as this wave washes over the ship and up the sail. One of the guys told his shipmates he was thinking about unclipping his harness to float to the surface and decides to hold off, and the water drains off and they are still afloat."
I've heard reports that there was pretty heavy weather off the southern New England coast last week, and every once in a while you get a "rogue wave" like that. I'm just glad the guy didn't unclip -- the consensus among everyone I've talked to is that the best thing to do is assume that even if the boat makes an inadvertant dive, the rest of the crew will be able to drive her back to the surface, so you should stay clipped in and hold on....