The boat is a Rod MacAlpine Downey design (Also designed the Shark) and was the best of the best in its time. They are pretty quick, but not a lot of space except for weekending.
I don't think they are as fast as any modern racer/cruiser, however.
Then in 1980 or thereabouts the MacGregor 36 set new standards of big cat speed and were about as fast as a Hobie 18.
Rick