The searchlight on the bridge roof is driven from a joystick and its controller logs every movement and the bearing it points at. On the stretch, with the joystick untouched, the controller logs the light training to two seven five and holding, and the light comes on, and what it lights is the sea.
I am the third officer, and the searchlight is one of the pieces of bridge equipment I test on my watch.
How it is controlled.
A joystick on the bridge console drives the mount in bearing and elevation, and a switch lights the lamp. The controller logs joystick input, mount position and lamp state, because a search for a man overboard is an inquiry afterwards and the log shows where the light was pointed and when.
With the joystick centred and the switch off, the mount does not move and the lamp is dark.
On the stretch, the controller logs the mount training to a bearing of two seven five relative, which is a little forward of the port beam, and the elevation dropping to the water, and the lamp lighting.
The joystick log shows no input. The switch log shows off. The lamp is on, and the mount holds two seven five for about six minutes, and then the lamp goes out and the mount returns to its stowed position.
I have stood beside the joystick with my hand off it and watched the mount move above me through the bridge windows, and the beam go out across the water on the port bow, and hold.
What it lights is water. Flat sea, in the beam, for six minutes, moving with the ship, at a range of about four hundred metres.
What has been checked.
The controller. Replaced. The joystick. Replaced. The lamp and its relay. The mount's motors.
The power. With the searchlight's breaker open on the stretch, the mount does not move and the lamp does not light, which is what a dead circuit does. The controller, which is on a separate supply, still logs the mount training to two seven five and the lamp lighting, from a mount that is dark and stowed.
So the log knows where the light should be, whether or not the light can go there.
The bearing.
Two seven five relative, at four hundred metres, on the stretch, is a position in the water. I have plotted it from a dozen crossings and the positions cluster on a spot the chart marks with nothing, over thirty one metres.
I have not been able to find out what is there. The harbour has no record. The chart is clean. The bottom is sand. There is a war memorial in the port with a list of names and no positions, and I have decided not to take that further, because it is not mine to take.
What the light does in the last minute.
For five minutes it holds the spot. In the last minute the elevation log shows the beam lifting, slowly, from the water to the horizontal, and the bearing sweeping aft along the ship's side, the way a beam sweeps when it is following something that is passing down the side of the ship, close, at the ship's own speed, and then the lamp goes out with the beam pointing at the stern.
What is done about it.
The searchlight's log is filed with a note that it exhibits autonomous operation on the stretch and is otherwise serviceable, which is true, because it works perfectly when a person drives it, and the company has accepted the note.
What I do.
I keep the watch.
The one thing I have changed is that I do not go out on the port wing while the light is on the spot.
The reason is a night in the winter, on the wing, watching the beam on the water at two seven five, four hundred metres off, flat sea in the light, and in the last minute the beam lifted and swept aft, as it does, and I turned with it, and it passed along the ship's side at the height of the car deck, and in the light, for a moment, on the water alongside, level with me, keeping pace, there was somebody, floating on their back, and their face was lit, and they were looking up at the bridge.