Port Calculator

Let me know if its useful and if the values match the other
programs in use. If you get an error message, maybe your Fre
is too high for the size box (make it smaller) or maybe its
too low for a too small box. Its not real graceful about
this. There is a limit of port diameter of 1" to 8", and box
depth is assumed to be 10", and the port can't be any longer than
70% of the depth. I guess that needs to be another input.

Chris