Nacra sail numbers used to correspond to the hull numbers like you refer too - but they now do the same now as Hobie. When I ordered my new sails for my Nacra 6.0NA (#209), I received sail #404. However, at my request, they gave me the digits for 209 if I wanted to peel off the new sail number in lieu of my hull number. This doesn't really matter since they index the sail #'s - nobody is getting #209 or #404. The whole point of all the sail numbers is to ensure that two boats don't show up on the start line with the same numbers right?