My favourite signs always combine simplicity, elegance and practicality.
They are often so effective that technology can’t improve on them. Cats’ Paws, the ruffled patterns on the water’s surface that tell us a gust of wind is on its way are a good example.
Transit Lines are a worthy member of this group.
Whenever any two fixed objects can be seen in line, that is one in front of the other, it means we are somewhere on the line that goes through those two points. This is called a ‘transit line’. Like so many powerful signs, this might sound too obvious to be valuable. But it is a truth that has saved thousands of lives.
If a bridge can be seen below a church steeple on a distant hill, it follows that you are on the line that passes through the two. It is impossible for you to be anywhere other than on that line. Simple certainty in navigation is worthy of celebration.
The value is most dramatic when we are in apparently featureless terrain, but can see features in the distance. This is true on land and sea.
In an ideal example, you might be wandering across a bleak and barren moor, a copy of Hounds of the Baskervilles in your pack. Looking one way you see a radio mast in line with a hill summit. You are on that line. Looking in another direction, you spot line the edge of a plantation wood with the edge of a lake. There is only one place on Earth where those two lines will meet like that. You could bury treasure on that spot and find it easily a year later.
The sea is never featureless, but its features change by the second. And the navigation dangers are greatest near land. Sailors have used Transit Lines to find their way safely into harbours and ports for millennia. Natural ones are ideal, like jutting rocks, which I have used in the tricky waters of the Channel Islands many times. Often it is necessary to either build or borrow objects. Harbour Masters paint buildings certain colours or place marks in the sea, like posts, lights or buoys.
Transit lines are also sometimes known as ‘leading lines’ or ‘range lines’.
In the video above, watch as the two crosses align, this marks a shallow semi-secret channel. It is safe for some vessels to approach near high water.
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