He could detect shallower water by colour, and see the light of invisible lagoons reflected in the undersides of clouds.
Each wind was given a name, which along with the colour of water or the height of waves was used to help forecast the weather.
Upriver here and at the Sandrift River, which runs parallel 10 miles to the east, the colour of the water is striking - imagine looking into a cup of strong, dark coffee.
Participants also ward off evil during the festival by bathing in flower-scented water, wearing five-colour silk, hanging plants such as moxa and calamus over their doors, and pasting paper cut-outs in their windows.
The tide was high, and for a hundred feet away from the shore, the water appeared to be the colour of green milk, the waves having sluiced chalk from the foreshore and cliffs, which stained the sea white.
Keith Noble, who took photos, said he first saw it flying out over the water and was "struck by its vivid colour".
"With my vision, when I look at the target, it looks as if different colour paints have been dropped in water, " he tells me.
Little lagoons, glassy blobs of brilliant blue water, punctuate the ride, pockets of sharp colour in barren nothingness.
Tiny particles of rock ground fine by the glaciers that feed it turn the water milky and give it this astonishing, alien colour.
When the first navigators came here, there were lots of holes that rain water gathered in and over time it turned the colour of brandy or whisky.
Batik is dyed by proud craftspeople who draw designs on fabric using dots and lines of hot wax, which resists vegetable and other dyes and therefore allows the artisan to colour selectively by soaking the cloth in one colour, removing the wax with boiling water and repeating if multiple colours are desired.
Remarkably, the processes that cause colour vary radically in, for example, flames, water, various crystal, plants, metals and rainbows.
This substance (an iron-magnesium silicate whose greenish colour is reminiscent of olives) weathers rapidly in the presence of water.
As well as black-and-white photographs there are some snippets of film and rare colour transparencies, rescued from the sinking Endurance by Hurley, who plunged into the icy water to grab the plate glass negatives.
Not so China's poorer interior, where the dark colour of colas is associated with the dark tea traditionally used to mask the sediment in the local water.
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