Above image for decoration only, there is no association between m/y Triple Seven and Nauticast bug |
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| Occasionally a strange vessel can be seen on an AIS system transmitting the following details : |
| What has happened is that the ship has a specific model of AIS transponder which will reset to default static data following long power loss or if the battery for backup of the onboard memory has failed. |
| The following units (at least up to a certain date of manufacture) are affected. |
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- Raytheon Marine RM808 AIS
- ACR Global Watch UAIS
- Marine Technologies Bridgemate AIS
- Nauticast X-Pack DS
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| Recently I was on a ship which had this exact problem. They had sustained a few seconds of power loss and the static data which was entered into their Nauticast AIS transponder reset to the default data originally specified by the manufacturer. |
| Static data is entered into AIS units manually by a ship's crew and includes as per the table above, the ship name, call sign, mmsi, IMO number, status, destination, ETA and ship type. These are the basic fields, there are also a few others in the AIS specification. |
| In this case it was likely that the internal battery of the unit had failed probably due to age. The purpose of this battery is to keep the static data in the memory during power loss. The reason the memory needs power to keep the data is because of the type of memory used namely volatile memory which will keep data only as long as power is supplied to it. |
| It is suprising that the manufacturer did not use instead a non-volatile memory type like flash memory which would not require constant power to keep the data. |
| Another suprising thing is that the vessel did not have the AIS transponder connected to the emergency battery power for the GMDSS system. It could therefore be expected for this to be not a rare thing to encounter. |
| The carriage of AIS transponders remains a mandatory requirement under SOLAS for relevant vessels and should always be on. |
| There is provision in the regulations for the checking of the static data of the AIS unit by the Officer of the Watch. |
| To ensure that own ship's static information is correct and up-to-date, the OOW should check the data whenever there is a reason for it. As a minimum, this should be done once per voyage or once per month, whichever is shorter. The data may be changed only on the authority of the master. |
| So if the minimum checking is done according to the regulation the static data will be checked probably at the beginning of each voyage or once a month. It is possible for a ship which loses power at anchor or at berth to be transmitting the default data instead of the correct data until this checking takes place. Of course as long as they have a power loss for a long duration that the memory backup battery cannot last for, or indeed if they have a battery which has become defective due to age. |
| The manufacturer of these units has recommended regular checking of these units to test the battery has not failed. However it is likely that some crews are not checking this and taking corrective action. We are also not aware of any recall of these units to fix the problem permanently. |
MMSI 1193046 changed name from [ATHANASIOS K ] to [NAUTICAST ]
MMSI 1193046 changed name from [PEGASUSII ] to [NAUTICAST ]
MMSI 1193046 changed name from [NEPTUNE THALASSA] to [NAUTICAST ]
MMSI 1193046 changed name from [STELIOS B ] to [NAUTICAST ]
MMSI 1193046 changed name from [ESENSE ] to [NAUTICAST ]
MMSI 1193046 changed name from [MSC SAMANTHA ] to [NAUTICAST ] |
| Since the AIS system is based around the MMSI numbers of the vessels and this is how targets are recognised by AIS units receiving the transmissions, it is possible for target swap to occur if any units are using the manufacturer specified default MMSI 1193046. Therefore receiving AIS units will think they are all the same vessel and may plot only one of the vessels at the same time. |
| Again we can look at a shipplotter log file and see this occurring. |
MMSI 1193046 changed name from [PEGASUSII ] to [ATHANASIOS K ]
MMSI 1193046 changed name from [ATHANASIOS K ] to [NEPTUNE THALASSA ]
MMSI 1193046 changed name from [STELIOS B ] to [NEPTUNE THALASSA ]
MMSI 1193046 changed name from [STELIOS B ] to [ATHANASIOS K ]
MMSI 1193046 changed name from [ESENSE ] to [ATHANASIOS K ]
MMSI 1193046 changed name from [ATHANASIOS K ] to [MSC SAMANTHA ] |
| It is also deficient that the manufacturer designed the units to allow transmission with the default MMSI set. |
| The same target swap could occur if several units reverted to their default settings, especially MMSI after power loss and battery backup failure. In that case the MMSI 1193046 would have changed name from NAUTICAST to NAUTICAST but of course that is not a name change and therefore is not shown in the shipplotter log. |
| So now you know what is the ship called NAUTICAST. Since these units are quite popular it is likely you may see one or more at every large port. |
