Sado Island Ferry: How rough is the sea?

Hello,

I want to go to Earth Celebration on Sado Island, taking the ferry from Naoetsu to Ogi.

As I get seasick very easily (and quite badly), I would be interested to know how bad the waves usually are. The ferry in question seems to be a catamaran-like ship (bottom one on this website, http://www.sadokisen.co.jp/language/en/ship/).
Going directly to Ogi would be much more convenient than taking the Jetfoil to Ryotsu and then having to travel all the way down to Ogi on Sado, but of course the Jetfoil would be much quieter, I suppose.

Would anyone have any experience with the Naoetsu-Ogi route and ferry "Akane"?

Thank you.

It depends on the weather, so there is no 100% correct answer. I've been on both the ferries to/from Ogi and Ryotsu, and in good weather never noticed any rolling even though there were small waves. Only one time on the ferry to Niigata, the wind was strong and there was a small roll to the ferry, but it wasn't enough to make anyone I noticed uncomfortable.

However, if you have to cross on a windy day, stock up on Dramamine or whatever works for you. Also, lying down somewhere with your body perpendicular to the length of the ship (lie down with your feet pointed toward the center line), reduces the feeling of motion. On a rough day, I like to get out on the lee side of the ship and watch the horizon.

Here's a picture of a ferry I took while it made its way through a typhoon; almost everybody on board was green. As I said, it's weather dependent. At least the crossing to Sado isn't very long.
https://www.flickr.com/photos/anaguma/2831100848