Copyright Law of the United States of America and Related Laws Contained in Title 17 of the United States Code, Circular 92 · United States
Section 1301. Designs protected [3]
(4) A "hull" is the frame or body of a vessel, including the deck of a vessel, exclusive of masts, sails, yards, and rigging. (5) A "plug" means a device or model used to make a mold for the purpose of exact duplication, regardless of whether the device or model has an intrinsic utilitarian function that is not only to portray the appearance of the product or to convey information. (6) A "mold" means a matrix or form in which a substance for material is used, regardless of whether the matrix or form has an intrinsic utilitarian function that is not only to portray the appearance of the product or to convey information.
Text from Project Gutenberg, public domain in the United States.