Welcome to the board! Storm at sea in batiks would be lovely.
Some more info is needed, however. A king mattress is 76''x 80''. How much will hang over the edge? 5"? 14"? will there be a pillow tuck? As you can see, the dimensions of a bed quilt can vary widely. Also, which is the 'traditional' pattern? there's one with a single sashing and one with a double.
I have the book "Storm at Sea Quilts" by Wendy Mathson.
http://www.amazon.com/Light-Storm-Qu...=wendy+mathson
The precise yardage is calculated by determining the number of each type of patch.
http://emptyspoolsseminars.com/2014/04Mathson.pdf
In general, Storm at sea has lots of seams, which requires lots of yardage. She has a sample quilt, 60X80, and lists fabric requirements of about 10 yards.