I saw this and didn't want to wait until the next time the discussion comes up about 'how fast is your boat' or 'should I get it documented with the Coast Guard or registered with the state'.
I was thinking of putting this up on the cruisers forum but was concerned that it might become too convoluted because he did not seem to be displaying a flag. On the other hand it's a bit more complex than just hull speed vs speed through the water when you consider the affect of tides in regards to course made good and what happens when you disregard calculating vectors and the AHJ.