This is the electric wrist band that I used for a while and worked for me, whap it up to number 5 if you start feeling sick and you'll be right as rain !
Relief Band Explorer Motion Sickness Relief System £119.99
My missus is also terrible on boats and in the air and shes used it several times with excellent results.
Also try some ginger gum stuff, ginger helps reduce nausea:-
Ginger Gum - All-natural relief from nausea with a great uplifting flavor