46 CFR 169.307 - Plans for sister vessels.
Plans are not required for any vessel which is a sister ship to a vessel, provided that -
(a) The approved plans for the original vessels are already on file at any Marine Inspection Office;
(b) The owner of the plans authorizes their use for the new construction;
(c) The regulations have not changed since the original plan approval; and
(d) There are no major modifications to any of the systems used.