Searching is how you get to one particular hull rather than whatever is passing. Use Search boats, beside the account icon on a computer and behind the magnifying glass at the top of the screen on a phone.

The four ways to search

Type at least three characters; one or two is too little to search on, and the box says so rather than telling you nothing matched.

• A name is the way in for most people, and it is enough on its own. You do not need a number to follow a vessel.
• An MMSI is the nine-digit number assigned to a vessel's radio identity. All nine digits find its record, which helps distinguish boats with the same name. Check the vessel details too: a radio can be programmed with an incorrect number. You will find a boat's MMSI on her radio licence and on many vessel-tracking sites.
• A call sign is the short radio identifier a vessel is licensed under, a mix of letters and numbers.
• An IMO number is a permanent seven-digit number carried by larger commercial ships. It stays with the hull even if she is renamed or reflagged, which makes it the reliable way to follow one particular ship across a change of name.

Call signs and IMO numbers widen a search rather than carrying it. Both are reported by a minority of vessels, so a search on one can come back empty for a vessel who is plainly on the chart. If that happens, search her name.

Reading the results

Each result carries what you need to tell two vessels of the same name apart: her type, her length, her flag, the water she is in, and how far away she is and in what direction.

• Distance is measured from your own boat when one is linked to your account and has reported recently, and otherwise from the middle of the map you are looking at. The results say which of the two they used. Where the only position available is too old to mean anything, the distance is left off rather than guessed.
• A badge on a row says why it is there when there is a reason: Your boat, Following, Fleet-mate, or Saillogger for a boat that keeps her logbook there and shares it. Those rows are lifted up the list, so an exact number match comes first, then the boats you already have a connection with, then everything else by how well the name matches.
• A vessel nobody has heard from lately is still returned, labelled with how long ago that was, and opening her does not throw the map across the world: you get her card where you are.
• Results come twenty at a time, with Load 20 more under them and a line saying how many matched. Past two hundred it stops counting and says so; narrow the search rather than paging through.
• Not every result is a ship. Navigation marks, base stations and search and rescue aircraft broadcast on the same system and land in the same list. Where a row is one of those, it says what it is instead of naming a vessel type.

When a search comes back empty

• "No boats match that." Either the name she broadcasts differs from the one you typed, or no receiver has ever reported her to us. Try a shorter, more distinctive piece of the name; if you can get her nine-digit MMSI, searching that settles it either way.
• "We are not tracking MMSI ... yet." The number is a valid one and we have never had a report for it. Follow it anyway asks the network to watch for it.
• If search says it is busy, that is us asking you to slow down rather than a verdict about the vessel. Wait a moment and try the same words again; it is not the same thing as no match.

What her panel tells you

Tap a vessel and her panel opens with what AIS reports about her.

• Her name and her MMSI.
• What kind of vessel she is, from the type she broadcasts.
• Her flag. This is the country whose authority issued her MMSI, which is usually but not always where she is registered. For most vessels it is worked out from the first three digits of the MMSI, which is how it can be shown for boats that have never sent us a full identity report; where a vessel has reported her flag herself, that is what you see.
• Her speed and her course, as last heard.
• Whether she is moving or stopped, and where.
• When she was last heard. The number to read: everything above it describes the moment of that report, not this moment.
• Her length and beam, which is how long and how wide she is.
• An AIS class and a destination, on the vessels that broadcast them. Both are ordinary AIS fields and a minority of traffic sends them. A destination is typed in by hand aboard, so read it as a note rather than a fact.

Her status line reads a passage, not a single report. She stays under way until her reporting settles enough to say she has stopped, so one quiet fix in the middle of a crossing does not tie her up and untie her again. That is why the line can say she is under way while her speed reads zero: the speed is the last figure AIS heard, and the status is what her recent reporting adds up to. The place in that line follows the same rule. It names where she is lying once she is confirmed there, and where she left from while she is on passage, so it never puts her at a place she has already left.

Her panel carries no ETA and no record of the ports she has called at before. Where the positions come from says why.

Boats that log with Saillogger

Some owners share a journal, their boat's photo and the logged track of their current passage. Boats that log with Saillogger explains these extras and how an access password affects them.

The actions on her panel

• Follow starts the notices and puts her on Favorites. Follow your first vessel
• Add to list puts her on any other list of yours. Lists
• Message needs a reachable boater on the other end. Most traffic on the chart has nobody behind it, and that is the ordinary case rather than a fault. Messages
• Add photo sends a photograph of her to the shared catalog. Vessel photos
• Her photos open full screen, with the count on the cover so you know how many there are.

Choosing what reaches you

Following a boat enables departure and arrival notices. Use Notification settings to choose in-app notices, e-mail and, when available, push in the iPhone app for each boat. Departures and arrivals covers the settings, including list notices and muting.

Track history

AIS track history draws where she has been, as AIS heard her, and Fit track frames the whole line.

The panel offers three windows: the last 24 hours on every plan, the last 7 days with Plus, and the last 30 days with Pro. The windows beyond your plan stay visible and say which plan unlocks them rather than disappearing. Tap a window to draw it, tap it again to put the line away.

The line is a record and not a forecast. A trace may hold no approach at all, and a vessel is free to take a different line next time, or none.

The panel collapses to a slim bar when you want the chart back, and the vessel stays selected.