personally, i'd go and have a word with your doctor. he will be able to prescribe something which will definately work. i would have suggested domperidone but i don't think it's used for children, it's what we both take and works a treat. we've done many ferry crossings, long and short, in all weathers, and don't suffer any sickness since taking it. nothing worse than potentially having 5 kids throwing up and maybe feeling a bit sick yourself so i'd defo see the doctor if i was you.