PA 80 06 fin range ? for Ian

[marksw]

Hi Ian - should have included this in the strap question.

Do you think it can take a 20cm fin with a 4.0m? Or this too small?

I also have a 22 for 4.5 weather. Only using board with two sails. Maybe crossover with a 5.0m - in which case 25cm fin?

There seems to be this rough formula of multiply your sail size by 5 for fin size?

Many thanks again...Mark