[C38] How to approach an argument with a sailor

[Anders Finn]

Advice seeking time.

So, I've got a friend who sails on a VERY fast boat. A very winning 
boat. Probably one of the fastest in San Francisco. It's crewed by a 
bunch of amazing sailors including some Cup guys. However, she's not 
really a sailor and I've had to explain things like what a knot is vs 
mph. The boat is a Santa Cruz 37 rates in a 27PHRF. Now, she claims and 
has some text messages from other crew saying they've hit 26knots in the 
bay. I call BS. I pull out all my math on hull speed, plain force 
calculations on what it would take to make that boat go into full plane. 
I've tried showing what PHRF means and that a 27 means they only average 
1/2 knot faster than the J/105's. I've tried pulling out their race 
times and showing they're only averaging about 6-7knots during races. . 
This does not matter.

  Probably most of us have seen exceedences in hull speed for our boats 
going down waves and whatnot. However, that's not the claim. The claim 
is they REGULARLY go 16-20 knots in bay races. This is 2x or more their 
hull speed. .

Thoughts on how to explain this or anyone have experience with a SC37?

Anders