I took one Bonnie at night, the whole cruise, starting one day ahead. We had rough seas a couple days, and on those days, I could feel the Bonnie wearing off about 21-22 hours after taking it. Also, I felt queasy enough to have to lay down for about 20-30 min those couple of days - middle of the day. Overall, it worked well for me, a motion-sickness prone person.
I did try Bonnie out before leaving on the cruise. I did put a priority on staying hydrated too (definitely helps overall), and I did bring a small pharmacy with me (it was a long cruise over some known rough seas), that included ginger caps, essential oil drops, sea bands, and patches. Thankfully, the Bonine worked better than expected and it was all I needed.