Precision 21 foot measurement of 130-35 genoa? HELP!

[eaglecreeksailor22]

Hello all, "I get along with a little help from my friends". A heavy 155% furling genoa came with my recently purchased P21. On our fluky wind inland lake her in central Indiana I have always preferred a med weight 130-35 genoa. But I do not know the foot measurement to be able to look for a used one. Any one Know this?
Thanks in advance,
Rich