with reference to the definition of 'fixed platform' in this section and section 10, means a vessel of any type whatsoever not permanently attached to the sea-bed, including dynamically supported craft, submersibles or other floating craft, but does not include-
| a) | a warship; |
| b) | a ship owned or operated by a State; or |
| c) | a ship which has been withdrawn from navigation or laid up; |