Welcome to our happy little corner of CC
I agree with zqvol that you shouldn't let the thought of seasickness deter you from sailing on SD. Mother Ocean and Mother Nature have minds of their own so there is no hard fast rule in terms of the waters in the Caribbean being one month/week than another.
Luckily I don't suffer from seasickness but I heed the captain's advice when he suggests seeing the concierge about those magic pills.
Other homeopathic methods that I have found to work for DJ's DH are ginger ale, ginger tea and ginger candy.