Brobu,

PLease gether the following info :

Overall weight ex spi (if you have only overallweight inc spi than I can use that too)
Mainsail area
Mainsail luff length
Jib area
Jib projection on mast (often this is equal to the leech length)
Length hulls are of P19 I guess

When you have these sorted out than I'm willing to calculate the P19 MX number for you. PLease provide the sources you used too.

WOuter