The IX (unclassified–miscellaneous) hull classification symbol is used for ships of the United States Navy that do not fit into one of the standard categories.

[1][2] Similar lists of 'miscellaneous' ships can found at and Ship status is indicated as either currently active [A] (including ready reserve), inactive [I], or precommissioning [P].

Ships in the precommissioning category include ships under construction or on order; IX ships are generally not ordered as such, but are rather converted from other roles.

These vessels usually fall into these categories: Currently only one ship, USS Prevail (IX-537), actively carries an IX hull symbol.

See also During the naval build-up for World War II at least 45 vessels of Maritime Commission (MarCom, later MarAd) standard designs were converted to US Navy unclassified miscellaneous vessels (several after suffering heavy damage in commercial service): Armadillo-class: MC type Z-ET1-S-C3 hulls, mobile base storage tankers[16] Other unknown classes Trefoil-class: MarCom B7-D1 concrete barges Other unknown classes IX-236 through IX-299 unused IX-328 through IX-500 unused A number of submarines were briefly given the IXSS hull symbol in 1971 prior to their disposal, nearly all had previously held the AGSS designation.