DEPTHS AND AIDS TO NAVIGATION The channels depths are liable to frequent change and the buoys are moved accordingly. Charted details cannot always be relied on. DEPTHS IN HARBOURS Depths in harbours and along quays are maintained by dredging. Consult the pilot for the latest information. VESSEL REPORTING For details of the Nieuwe Waterweg Vessel Traffic Service see the Netherlands Coast Pilot (HP1) or ADMIRALTY List of Radio Signals. SUBMARINE CABLES AND PIPELINES Mariners are advised not to anchor or trawl in the vicinity of submarine cables and pipelines. Pipelines are not always buried and their presence may significantly reduce the charted depth. They may also span seabed undulations and cause fishing gear to become irrecoverably snagged, putting a vessel in severe danger. PORT SIGNPOSTING SYSTEM Berth numbers e.g. 6001-6105 relate to the Port Signposting system. These numbers correspond to the numbering of the waterfront. The port numbers are indicated in black figures on yellow boards.