Just a quick comment. I have been sailing the I-18 for four seasons now. I am one of three in the entire state of Florida. 2 have carbon masts and 1 aluminum. I have a carbon mast and yes, it is very much lighter than the new aluminum F18 mast. The I-18 is still able to compete heads up this year only with the carbon mast. Next year you will need to change the mast out if you are to compete in the F18 class. I don't know why anyone would do that given the fact that the F18 hulls are far superior to the I18 hulls. I have now done hundreds of miles on both boats and I think the Nacra F18 is the best.
