I have yet to be seasick but that may be due to always being careful what I eat and don't drink. Same as above replies. If you can. always scan the horizon and think positive. Sounds stupid but it does help.
The scopalene(sp?) patch is great and I have used that several times out halibut and tuna fishing when seas were just nasty. I think that is your best option.
When a fellow fisherman out 60 miles in rough seas for tuna was looking green and probably ready to puke... one of the deckhands gave him some ginger snap cookies. He was feeling much better within about 20 mins. I took some ginger capsules last time out tuna fishing when I didn't have the scopalene patch and could tell it did help as I didn't get sick.
I tried some meclizine a day before the trip but it made me feel strange. I didn't like it.
So I would say the patch but always carry some "real" ginger product.
Goodluck