AIS voyage data on getting under way

What you do on the bridge

1. Draught
2. Destination
3. ETA in UTC
4. Persons on board
5. Status: under way

The oral questions, and what a good answer covers

The key points are in our own words. In the course, these questions come once you have done the job.

1. What information does AIS send, and which of it does the officer of the watch enter?Often asked

   A good answer covers:

   • Static data, set at installation: MMSI, name, call sign, IMO number, length, beam, type and antenna position
   • Dynamic data from the sensors: position, course and speed over the ground, heading, rate of turn
   • Voyage data, entered by hand: draught, destination, ETA, hazardous cargo and persons on board
   • Check it at the start of every voyage, and whenever anything changes
2. What are the limitations of AIS for collision avoidance?Often asked

   A good answer covers:

   • Not every vessel carries it, and it can be switched off
   • The data is only as good as what the other ship entered, or her sensors give
   • Positions come from her own GNSS, which may be wrong; her heading and COG may differ
   • Updates are not instant, so a turning ship may lag on the display
   • It does not replace radar, plotting and a proper lookout, and the collision regulations still apply
3. When may AIS be switched off?

   A good answer covers:

   • The time and reason go in the log
   • It goes back on as soon as the threat has passed
   • In port, follow the port's rules on AIS
4. We're about to weigh anchor. What's wrong with our AIS?

   A good answer covers:

   • Status shows moored, and is not changed to under way using engine
   • Draught 2 metres, the shipyard figure, not her present draught
   • No destination
   • No ETA
   • Persons on board shown as none

   Show me on the bridgeThe AIS unit on the after bulkhead, as the last officer left it.

How the lesson runs

The tutor's narration from the lesson, step by step. On the bridge, each control lights up as it is named.

1. Brief

   We're weighing anchor in the Lower Bay. The last officer left the AIS showing moored, with the draught she had in the shipyard, and nothing else.

   Other ships, the VTS and rescuers all read what we send. So before we go, we put the voyage data right, and the status changes as soon as we're moving.

2. Draught

   Start with the draught. Her present draught is 3.9 metres. Other ships and the VTS judge where we can go from it, so the shipyard figure won't do.

3. Destination

   Destination: New York. You can write the name, or use its UN location code, U S N Y C.

4. ETA in UTC

   The master's ETA at the berth is eleven hundred ship's time on the twenty-eighth. AIS always takes the ETA in UTC, so convert it first.

   Look at the clocks. Ship's time here is zone minus five, so add five hours to get UTC. That's sixteen hundred UTC on the twenty-eighth of October.

5. Persons on board

   Persons on board: thirty-one, from the crew list. If we ever need rescuing, that's how many they'll look for.

6. Status: under way

   When the master orders us ahead, put the engines ahead. Within three minutes of getting under way, the status must say under way using engine. It's set by hand, so it's the one most often left wrong.