What SOLAS covers
SOLAS is organized into chapters. They address, among other things, ship construction (subdivision and stability, machinery and electrical installations), fire protection and firefighting, life-saving appliances and arrangements, radiocommunications, safety of navigation, and the carriage of cargoes and dangerous goods.
Two chapters are especially far-reaching: Chapter IX makes the ISM Code mandatory for safe operation, and Chapter XI-2 makes the ISPS Code mandatory for maritime security.
The certificates it generates
Compliance with SOLAS is evidenced by statutory certificates issued on behalf of the flag administration, including the Cargo Ship Safety Construction, Safety Equipment and Safety Radio certificates (which may be combined as the Cargo Ship Safety Certificate), and the Passenger Ship Safety Certificate for passenger vessels.
Staying ready
Owners keep these certificates valid through periodic surveys. Independent document and condition review ahead of those surveys, and ahead of Port State Control, is the practical way to ensure the ship matches its paperwork.