How thick is a gel coat usually?

[1985 Century Mustang]

I have a mid 80s Century Mustang Bowrider. Im curious to know how thick the gel coat usually is on boats from the 80s.

 

[tpenfield]

typically 0.020" - 0.030"

 

[Scott Danforth]

Thinner than you would like when you sand thru it....lol. however usually like Ted stated