I was travelling between Long Beach and San Diego (20 or so miles offshore) about a year ago, and came across one of the Marine Corps hovercraft. Those things are HUGE, maybe 125+ feet. (and they go 80 knots!!!) It was rough, and the hovercraft was rolling and pounding her brains out, throwing so much spray you could hardly see her at times, even though they were going slow.
We were enjoying our smooth riding Hatt, barely rolling and taking no spray higher than the bow. It was easy to walk around without holding on at all, and the bridge enclosure never took a drop of spray. Gotta love it.