When I first moved to Cairns in 1986 I was dreadfully prone to sea sickness. I used to spew all over coral trout as I was pulling over the gunnel! I used to vow I would never go out again but as Flex said you can get your body used to it.
Your brain eventually learns what is going on and no longer sends messages to your gut and in some cases to your arse as well saying" Jetison all unnecessary cargo!!"
I havent been seasick in over ten years but I still take one at the start of an overnighter
John