surfing
It is the cumulative affect of boat speed and the current. The boat is still only capable of about 6 knots. If you hit greater than that it is because you had 3 knots of help from the current. We hit ten knots on my 30 footer, but we were literally surfing her on waves entering the mouth of the Cape Cod Canal.
A few years ago I co-owned a new 1984 30' Catalina, one of the co-owners was Ed. Ed and I sailed from Shorelina Marina at Long Beach, California to Marina del Rey and stayed at the dock overnight. The next morning the wind was brisk but we had to be back at our Shoreline dock that day. As we were leaving, the Coast Guard overtook us and suggested that we not go out. At that time a "small craft" warning was in effect. We elected to sail back to Long Beach that day and told the CG that we had sailed many times in "small craft" warnings and greater.
With the full main up and the 150, roller furling genoa flying we set the course at DDW and proceeded. Very quickly we were surfing and pegging the knot meter. Even though we did round-up twice there was no damage. We arrived at our dock, 25+ KM away in about 3 and one half hours. The sail was the best one I had experienced and I would do it again if given the chance.
Duane "novelman"