Here is a heavy full keeled boat in Puget sound.
What would the true wind be here Jeff_H?
There are many reasons the boat speed could be higher instantaneously. Momentum from a earlier gust or catching a wave are two I can think of off hand.
Not sure why we are hell bent on trying to prove Jeff_H wrong. Fighting a losing battle in this case.
There are many reasons to love our beautiful old long keeled boats but performance in light airs is not one of them.