Vessels API update rules

The goal of the Spire Sense Vessels product is to provide the most accurate snapshot of a vessel possible. To mitigate the uncertainties of AIS data, we have created rules that delay updates of Vessels to make the updates that we do have to be more trustworthy. These rules are subject to change as we learn more.

 

The fields for a vessel that are from static messages have a standard update rule that holds back an update until we have seen the same new value at least three times, and it is 90% of all updates since the last update we made. Voyage related fields are likely to be updated more frequently, which is why their rule is to update after we have had two updates of the same value after the currently set value. 

 

This means that an update to the name of the vessel will require at least three updates with the new name before we use it. Whereas an update to the destination or ETA will only need two updates.

Examples

Say that we have the vessel BOATY MCBOATFACE with MMSI 123456789 and IMO 7654321. The last updated destination was STOCKHOLM and this was set on 2020-06-01 00:00:00Z.

Could not update name because not 90% of updates are the new value

 

Timestamp

Field

Value

2020-06-01 01:00:00

name

SIR DAVID ATTENBOROUGH

2020-06-01 02:00:00

name

S1R DAVID ATTENBOROUGH

2020-06-01 03:00:00

name

SIR DAVID ATTENBOROUGH

2020-06-01 04:00:00

name

SIR DAVID ATTENBOROUGH

 

While we have three updates (even if they’re out of order) from our original name it is not allowed because there was an extra update that made the update percentage 75% of all received messages.

Update the destination with only two updates that are the same

 

Timestamp

Field

Value

2020-06-01 01:00:00

destination

SINGAPORE

2020-06-01 02:00:00

destination

GOTHENBURG

2020-06-01 03:00

destination

SINGAPORE

Because the original destination was STOCKHOLM when we get the second message saying the vessel is going to SINGAPORE the destination will be updated to SINGAPORE.

Like destination, eta is also required to have only 2 messages to propagate the change to Vessels API (no frequency check)