I think she floats and acts rather well in that video... nice one btw.! and great looking little ship!
You're running in what? 20 ft. waves? and with heavy weights in both ends compared to her tonnage, you will occational get that oscillating effect.
Looks convincing from here...
Silhoutte indicates a freeboard of some 2.2 to 2.5 meter along most of her hull, so you will get loads of "decks-awash" too...
If you want to alter her handling, there are values like drag up/down and weight/displacement to play with.
Please keep us updated - and welcome to the World of Modding!
/edit: found a (for me unknown) link with some nice stuff:
http://www.friesian.com/destroy.htm