Nacra trying to drum up some sales.
They are already making curved boards, so why not just stick them on the 16 too - although technically it should not be called an F16 anymore.
Boards must be straight so J C or L foils are not class legal.
They can be canted but only a maximum of 6 degrees from vertical, and they can be asymetrical.
There is not any rule about how straight they have to be, so "jibbing" or as I have heard them refered to as "lazy boat builder boards" would be legal.