Field notes: the night the unmatched list had fourteen contacts, and one was a drill

Fourteen is a lot for a Tuesday. Most nights the unmatched list runs four, five, maybe seven if there's weather pushing boats into a lane they don't usually sit in. Fourteen meant someone was going to be on the phone before the 0600 brief, and someone was going to be annoyed about it.

The list itself is nothing dramatic to look at. A row per contact: position, size class, time of pass, no AIS match within the window. You scroll it the way you'd scroll a ledger. Most of it resolves itself before you've had your second coffee. A 9-meter contact near the strait turns out to be a local skiff that's never carried a transponder in its life and never will, just because it's a 9-meter skiff. Two contacts cluster near a known anchorage, which usually means AIS was off because the engine was off, nothing more sinister than a crew asleep with the unit powered down to save the battery.

That left eleven. Eleven is still a lot.

One detail never made it into the handoff notes, though it probably should have: one of the fourteen was a drill. Not ours, we didn't run one that week. A neighboring unit had a vessel doing an AIS-dark exercise as part of a boarding-readiness drill, the kind where you deliberately kill the transponder to see if anyone's watching. Nobody told us. It wasn't our water, strictly, though the contact sat close enough to the line that it showed up on our pass.

We didn't find out it was a drill until the liaison call two days later, which meant the contact sat in our notes, unresolved, for two full days. For two days it was just another line in the pile, weighted the same as the other ten, pulled forward into the next day's list because nobody had closed it out. The real cost of a gap like that is you can't tell, from the list alone, which of your eleven open contacts is a drill boat, a transponder with a dead battery, or something worth sending a patrol asset after.

The ten that were left, after the drill got sorted, split about how they usually split. Six turned out to be AIS outages you could chase down afterward, two foreign-flagged vessels that likely just don't carry gear compatible with the receivers in that stretch, one that resolved itself two nights later when the same hull showed up on AIS forty miles north with a gap in the track that matched almost to the hour. One stayed open. It always does. One contact that never reappeared on AIS, never matched a known hull, and sat in that spot long enough that loitering was the only honest word for it.

That's the one a patrol boat got sent after. Out of fourteen.

The part that stuck with me was how ordinary the list made it look, sitting next to everything else. A list built off detection-versus-AIS correlation tells you what's on the water and what's broadcasting. Sorting out whether the gap is a drill boat, a smuggler, or a fisherman who forgot to charge his unit, that's still the job, and it probably always will be.

We've since made a habit of checking with neighboring units before gap-season drills, mostly so a night like that one costs two hours instead of two days. The unmatched list itself hasn't changed. If you're running that comparison by hand, pulling AIS logs against whatever imagery crosses your desk and squinting for the vessels that didn't check in, the daily version of that list is worth seeing before your next fourteen-contact night turns into a four-day one.

Next time the list runs long, ask who's drilling nearby before you call the boat.