Given your second post I would suggest, getting a H16, Prindle 16 or nacra 5.0

They will all take you, your friend and dad for a month and then be pretty much fun for the two of you without big bucks or being to much overpowered. All of these will carry you very well till you both gain weight after 18-20. They are light enough to be easy on the back and can I know the Prindle 16 can be righted by 300 lbs or a little less.

Wouter