"Many sketches and designs for the Naglfar were made. Early ones assumed this ship would fly through the air. In the end, however, the more subdued concepts which better fit the grounded feel of the witcher universe won out. The drawing above shows the final version of the Naglfar, the ghastly Hunt’s equally ghastly vessel."
from The Witcher 3 Wild Hunt Artbook
I had pleasure of designing the Wild Hunt Ship - Naglfar. The ship's design went through a long process before it reached its final shape. Gathering good references and 3D model was very helpful. Few words of explenation on my Facebook page : https://www.facebook.com/wojtala/posts/604899839657288