On a large ship in a narrow channel when the buoys are alongside they cannot be seen without leaving the centerline but the position can be judged by looking at the buoys ahead.
In a narrow buoyed channel, particularly at night if the ship is in the middle of the channel the alignment of the lighted buoys on each side of the channel will be the same. Visually they act some what similarly to a range except of course you don’t want to be on the range but off the range the same distance on each side.
When range lights are being used as a guide the visual distance that the range is open, how far apart the forward and aft range light appear to be depends on how far the ship is from the center of the channel. In the case of a buoyed channel if the ship is to the left in a buoyed channel the “range” made by the buoys to port will be more nearly in line than the ones to starboard. The starboard buoys will appear to be more open. If the ship is in the middle of the channel the appearance of each line of buoys will be the same.
In other words if the ship is in the center of the channel it will be off the “range” made by the buoys on each side equally.