I'll tell you what I have done when one of these guys refuses to alter course when I have the clear ROW sailing or powering. I hail them on 16, which as you know coastie monitors, thusly: "..High speed powerboat headed East 1 mi south of Craggy Neck, this is the sailboat dead ahead, what is your intention sir?..." Then when they blow by me close aboard I hail them again using their boat's name. The run of the mill sportfish or cruiser could care less but the large captained yachts definitely come right back and tell me to hold my course, which means "..stand by for incoming..." It's all we can do.