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Wednesday, September 12, 2012

The Vikings Ships and the Sea

So much were the ships a part of their self-image that the Vikings decorated and caparisoned each longship to display wealth, rank and power, at once impressing their friends and allies and awing their enemies. However much he loved fighting and warships, the Viking lived on the sea for many other reasons as well, and devised vessels to match his needs. When he turned his genius for design and construction from warships to ships for long-distance trade and exploration, and eventually for emigration to the farthest reaches of the ocean, he produced a boat equally extraordinary; stouter and sturdier, designed to brave the worst seas in search of landfalls far beyond any other Westerners’ wildest dreams.

That the Vikings succeeded in these epic voyages was attributable not only to their magnificent blue-water sailing vessels. They were superlative navigators as well— venturing boldly out to explore the unknown, and then repeating their voyages almost casually, with a certainty of direction that was nothing short of phenomenal. What lay behind all Viking seafaring was the Norseman’s instinct for the sea, a sense that seemed uncanny to the landsman, but it was in reality a prodigious body of hard-earned knowledge accumulated throughout centuries of nautical life.

The Viking drew great meaning from the look of cloud formations, from changes in winds and wave patterns, from ocean currents and ground swells, from sea fogs, water colors and temperatures. He could read information from the habits of sea birds, was alert to the over-water migration of certain land birds, and tracked the movements of fish and whales that came down from the north. A seasoned Viking navigator could tell when he was approaching the Faroe Islands by the swell building up over the banks surrounding the group. He would know he was nearing Greenland because of the abrupt change in the temperature of the water as he entered the polar current, by the pronounced change in the water’s color from ocean blue to green, and by the occasional presence of drift ice.

The Vikings were masters of the relentless currents that swirled around in the North Atlantic and arctic waters. The Norwegian Current surged powerfully up the coast of Norway toward the Lofoten Islands, tending to carry ships in its path speedily toward Iceland. From Iceland, ships setting a westward course were carried along by the Irminger Current and then whisked southward by the Greenland Current; finally they were propelled down the coast of North America by the Labrador Current.

Prevailing winds generally helped them on their way as well, blowing northward between Norway and Iceland, and southward between Iceland and Greenland. The elaborately decorated wind vanes mounted on the prows and mastheads of Viking ships testify to the sailors’ keen sensitivity to every errant puff, for it was only by taking full advantage of both the wind and the currents that rapid ocean passages could be made without tragedy.

Viking seafarers employed a primitive celestial navigation to help them measure course and distance. At night, Polaris, the North Star, was the primary heavenly indicator. This star was usually visible overhead, circling tightly around the pole below, and thus a boon beyond price to mariners. On clear nights, it required only a method of determining the angle of Polaris off the bow to determine a rough course. By holding a steady 90 degree angle from Polaris, for example, the Vikings could be sure that they were heading directly east or west. In later years this would be known as latitude sailing, and its ramifications for the Vikings were enormous, particularly on their great western voyages of exploration and trade across hundreds of miles of open ocean.

During the day the sun was the indicator used by the Vikings. To measure the suns values and apply them to navigation, the Vikings devised three ingenious navigational instruments that they called the sun board, the sunstone and the sun shadow board. The sun board appears to have been a bearing dial on which were marked compass points, radiating from a hole in the center. With the help of a pointer mounted on the dial, the Vikings were able to take a course bearing from the sun as it rose in the east or set in the west and to maintain any course simply by checking this crude triangulation each day. From Viking accounts it is known that Norse navigators were accustomed also to taking a sighting at noon when the sun reached the north-south meridian. Thus, although he had no magnetic compass, the Viking could make a reasonably accurate determination of his compass bearings each day.

Under overcast skies or in dense fog, the Viking made use of a remarkable calcite mineral crystal named cordierite, the Norse sunstone, found in Scandinavia and Iceland. When a crystal of cordierite is held at right angles to the plane of polarized light from the sun, the crystal instantly changes from yellow to dark blue. The sunstone was a real boon to Viking seafarers. Even in a thick fog or under a woolen sky, a navigator in mid-ocean could locate the exact position of the invisible sun by rotating a chunk of cordierite until it suddenly turned dark blue. Since it produced the same color change even when the sun was as much as 7 degree below the horizon, the navigator could continue to take sightings after sunset.

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