Coastal Navigation
December 26th 2006 18:52
A compass
Coastal navigation:
Staying in site of land, keeping an imaginary umbilical cord between your home and your vessel on the sea, is one of the earliest of the “black” arts. Building up information over the years, a skipper and then in turn his kin could fish and more importantly travel along coastal highways.
At first reliance was on the site of land by day. Being inquisitive as well as frightened they wanted to know the depth as well. Fishing lines with weights were first used then string and a rock and after a long while a line attached to a lead weight that had wax at the end and could bring up samples of the bottom. Shell, grey sand, mud is all now marked still on modern charts of the sea.
As ships became bigger and stronger sailors became a little braver and actually ventured further off shore and even out of site of land as long as their lead line could find the bottom they felt their umbilical cord was still attached. The lead line had to have a maximum depth it could be plumbed to. It was physically impossible to go any further and so it became known as “no bottom”. It was the fact that there was no bottom, I feel that made sailors say that the world ended here, rather than some hairy, fairy thing about the horizon.
Once sailors sailed to an area where there was no bottom, then they stopped exploring further out to sea and only ventured along the coast, as far out as the bottom stood. We know this as the continental shelf. Almost all continents and large landmasses have this and if you look through the ages, migrations that relied on the sea were restricted by this phenominum.
Navigational directions from England to Lisbon, in Portugal were simple enough. “Proceed down the channel to forty fathoms and grey mud with shell. Then turn left (port was not yet invented) and sail straight for Lisbon.”
More tomorrow.
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