WATER BUS IV — Port Tender · MMSI 503710300

WATER BUS IV has not broadcast an AIS position for 40 days. The most recent broadcast placed it in the Coral Sea, on 27 Sep 2026, 23:31 UTC. It was sailing from HORN to CLASS B. Vessels stop appearing on terrestrial AIS when they move beyond receiver range, so a gap does not necessarily mean the vessel is inactive.

WATER BUS IV broadcasts MMSI 503710300. The MMSI is the radio identifier used by AIS; the IMO number stays with the ship for life and does not change with re-flagging or sale.

WATER BUS IV is classified as a port tender vessel registered under the AU flag. The vessel-type classification is derived from the AIS Type field broadcast by the ship's transponder and full AU flag list at /flag/au.

MarineRadar shows the latest AIS broadcast from WATER BUS IV above, with current position, course, speed, and navigation status. Tap "View on map" to centre the live tracker on the vessel and watch its movement update in real time. The same data is available offline-friendly in the iOS and Android apps.

AIS transponders broadcast position every 2 seconds when underway at high speed and up to every 3 minutes at anchor. The position you see refreshes whenever the ship is in range of a coastal AIS receiver or a satellite pass — typically seconds in coastal waters and minutes offshore.

As a port tender, WATER BUS IV sits in the same design class as the other port tenders listed in the Similar Vessels section of the vessel page.