In the last several years we have never been on a ferry with outside seating and have not had any trouble with fumes. We have crossed when the seas were rough so I can see how someone could easily get sick. Since I have started using the drops I have had no issues with the crossings as far as getting sick. One time the crossing was especially rough, we made it to Anguilla, but I was pretty sure I was going to have to stay there rather than cross again!