I like your "make it a date" idea. Learning to appreciate sailing is hard enough w/o adding a 2yr to the mix.
Keep it simple, make it romantic and STRESS FREE for her (take care of packing the food and drinks yourself, at least the first couple of times) and really use it as an opportunity to "court her" all over again.
THEN, if she starts to appreciate sailing, see about classes.
Slow, steady and no pressure.