I get pretty bad motion sickness. Which is not wonderful when diving. Hyoscine works for me. The worst I've felt when I've had hyoscine has been mild nausea, even in awful conditions. I use the behind-ear patches, sold as transderm scopolamine (IIRC).
Scopolamine works well for me, too. After 2-3 days (on long sailing trips) I do get the side effect that makes it hard to focus my eyes at close distances (3"-9" or so).
My SO takes it when we're on boats, and she definitely feels - different. I haven't noticed her blabbing secrets, but I'll ask some better questions next time. :)
Ha ha. The dose isn't high enough for that. The main side effects are wicked dry mouth and drowsiness. The drowsiness can be a problem if you need to operate heavy machinery, like docking an 18-ton sailboat, but still better than being sick.
https://en.m.wikipedia.org/wiki/Hyoscine