It's amazing the difference in people and how some love something others can't handle. I'm like your dad, I get nauseous on the ocean, even on a glassy sea.
They do the cruise ship thing every year, and I've been with them on a boat off the Alaskan coast looking for whales. He was all over the boat while I was staring at placards inside the cabin, trying not to upchuck. lol
Passing on your recommendation for a powered boat, in your other comment.
Thanks!
Here's some advice regarding that for when/if you get seasick the next time out...being INSIDE a moving boat is the worst place to be. Your inner ear senses movement but you cannot orientate on a horizon. That is what causes the nauseous feeling. You'd do better sitting in the cockpit/flybridge outside while the boat is moving.
Someone said upthread that there are a lot of beautiful places you can't get to on a boat. Well, yeah, but there are plenty of beautiful places that you can ONLY get to on a boat! Lucky is the man who can do both!