Tinkerbellmagic, your DGS may be fine. As Sewsew said, everyone handles it differently. I got a bit sick the first night, never threw up though. I was still able to eat the yummy food!
The last night was rough but I didn't get as sick as I did the first night. I just didn't like the swaying and rocking. My biggest problem was the closet doors making all of that noise and the creaking in the room.
My DD didn't get sick at all the first night, but got terribly sick the last night. I did bring along a lot of medicine, herbal pills, wrist bands, etc. because she does get motion sickness in the car on mountain and backroad trips. I expected her to be sick the first night. She didn't do it though. It just came the last night.
I will say that the captain did warn us ahead of time about it. That was good because, like sewsew said, we were expecting it.
As far as the closet doors go, I didn't bring duct tape. I guess that may have worked. I am not sure. I guess my door's velcro was worn out. I didn't even see it. It definitely didn't work! I think that it is ashame, though, that you have to pack tape for the doors. For the price you pay you would think Disney could do something else about the doors........latches, locks or something.