The DOC is issued, and must be revalidated every 12 months, by the Flag State authorised auditors. Every vessel’s SMC must have an external audit twice every five years to revalidate it. In addition, the management department must carry out regular internal audits. Obtaining certificates is only the first step, procedure manuals have to be in place both ashore and on board each vessel and regular drills such as fire emergencies have to be carried out. Port State Control (PSC) officers have no power to detain a ship on the basis that its SMC is not up to date, PSC can only report this back to the Flag State. Having said that it is unlikely that a ship without an up-to-date SMC will not have some defects which will justify detention by the PSC. Although Port State Control is looked upon as a comparatively modern innovation, some form of practical port state control has been in existence since the 1929 Safety of Life at Sea (SOLAS) convention which was re-affirmed in subsequent versions of SOLAS. The control under that convention was, however, limited to ensuring that the ship had all the necessary certificates on board and that they were up to date. Where there were out of date or missing certificates or where there was a significant discrepancy between a certificate and the actual condition of the equipment concerned, the authorities did have the power to detain the ship until matters were made safe for passengers and crew. Similar powers were in place under the MARPOL convention.