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Ocean Chart

Today's Arts and Culture card from Conquest of Paradise is related to last week's Navigation card. Today's card, Ocean Chart, focuses on a specific aspect of Polynesian navigation.

Much of the navigator's art among the Polynesians was based on an elaborate oral tradition. But they also used simple devices as memory aids and teaching tools. A simple lattice of split bamboo, with white shells attached to represent islands, was one such navigational aid. Ocean charts depict the principles of swell refraction; sticks curved around a central point model how swells from opposite directions refract around an island and intersect in nodes- an area of confused sea, which is a valuable indicator of position.

While appearing simple, these "stick charts" are actually rather sophisticated. They do not depict the islands in their fixed geographic relationship to one another; instead, they show the islands in relation to the prevailing winds and ocean currents that would carry a canoe between them. The stick-charts are used to teach and record the swells of the sea itself. The charts were hardly maps in a western sense: the cowrie shells did signify islands, but they could often be taken to be any island. Distances were quite arbitrary and charts were meaningless without the guidance of their maker. They were not taken to sea, all being set in the memory.

Mau Piailug, a master navigator, explained his art:

Sunrise is the most important part of the day. At sunrise you start to look at the shape of the ocean-the character of the sea. You memorize where the wind is coming from. The wind generates the swells. You determine the direction of the swells, and when the sun gets too high, you steer by them. And then at sunset we repeat the observations. The sun goes down-you look at the shape of the waves. Did the wind change? Did the swell pattern change? At night we use the stars. We use about 220 stars by name- having memorized where they come up, where they go down.

When it gets cloudy and you can't use the sun or the stars all you can do is rely on the ocean waves. If you can read the ocean, you will never be lost. One of the problems is that when the sky gets black at night under heavy clouds you cannot see the swells. You cannot even see the bow of the canoe. A skilled navigator can be inside the hull of the canoe and just feel the different swell patterns moving under the canoe and he can tell the canoe's direction lying down inside the hull of the canoe.

Swells are waves that have traveled beyond the wind systems or storms that have generated them, or waves that persist after the generating storm has died away. Swells are more regular and stable in their direction than waves. Waves, as opposed to swells, are generated by local winds. Sometimes swells can be felt better than they can be seen, having flattened out after traveling long distances. The navigator can orient the canoe to these swells, and accurately guide his canoe to his intended destination.

In game terms, the Ocean Chart card provides its owner with a Victory Point, for inventing a valuable tool to aid in your people's ability to travel the open ocean. It also provides an advantage while exploring: its owner's Explorer will never again be lost at sea.

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