Another vote for scopolamine.
I battled mal de mer for decades.
I first got seasick when I was 14, on my first ocean dive.
I have been seasick numerous times and to different degrees on the ocean and even our local lakes until I tried the patch.
Since I’ve used the patch, I haven’t been seasick once— including five liveaboards.
One of the liveaboad trips included a Lombok Straits crossing which can be brutal as anyone who has made the crossng can tell you.
Some people are definately more predisposed to get motion sickness and all the positive visualizations in the world aren’t gonna change that predisposition.
(although I agree more time on the ocean will acclimate you if you can stay out there enough)
Even with the patch, stay away from the petrol fumes, book a room in the center of the boat, find something not moving to watch if necessary, eat some ginger, moderate alcohol, keep greasy food to a minimum.
Next week, I’m off to the Galapagos for liveaboard trip number 6.
When I went to my pharmacist last Saturday to get some patches for the trip, he said,” They’ve been recalled- no one in town has them.” I PANICKED!!! Then I got on the phone and found some at a Walgreens about an hour away. I got in the car and drove straight there. I can’t imagine being 600 miles out in the Pacific without the patch.