Monday, 25 January 2010

Sailing by the Stars - How the Ancient Sailors Did it

Technology is fantastic and with the plethora of electronic devices available today for sailors to find their way evermore easily, one wonders where it is going. There have been huge strides in recent years in navigation, radar, chart plotting, global radio contact, weather software programmes, proximity alarms etc.. It is there, available, easy to use so why wouldn't you use it?

But, like motoring, where there are so many devices now built in and attachable in cars that the question has been raised recently if there are so many distracting devices in a car (mobile phones and GPS being the main offenders) that the focus is being taken away from driving.

I wonder if this is happening also in sailboats? Earlier sailors such as the Smeatons, Sir Francis Chichester and certainly Captain Joshua Slocum would have eschewed (albeit they weren't available) them and went on to achieve fantastic conquests regardless.

The ancient Polynesian sailors colonised virtually the whole area of Polynesia in their ocean going canoes with just knowledge that the 'Navigator' carried in his brain and no instruments whatsoever.

The following is an extract from my ebook "Voyage of the Little Ship 'Tere Moana'.

.....'Sunday morning climbs up over the horizon and brings her captain, rising from his bunk, with it. WK stands on no ceremony, and her captain is met by the open case of his sextant on the chart table.

WK has brought his own with him, and is fiddling with the settings on both. Throwing a wolfish grin in his direction, our captain understands what is in store for him this morning. Navigation by the stars has a fascination from time immemorial.

The Polynesian and Micronesian sailors did it the best and were able to successfully navigate thousands of miles of open sea to arrive at their destinations. Very often, these were small lumps of land, or clusters of islands, that could be very easily missed. Many times, of course they did miss, and nothing more was ever heard of those unfortunates.

However, when you consider that all they had to guide them were the stars and a mind map of them, this form of navigation was amazing in its skill. Good navigators were revered. They developed what is referred to as a ‘Star Compass’ or ‘Star Map’, and this was retained in the navigators head. To know all those stars and maintain a course for thousands of miles according to the stars’ position in the night sky, required a consummate skill and a mighty store of knowledge.

An interesting anecdote is the way they expressed the coming and going of the stars. The east, or the beginning of the night was known as the ‘arriving’, because that was where the stars arrived for the night, rising from the horizon. The west on the other hand was known as the ‘entering’ because that was the point where the stars at nights’ end, entered into the sea.

An accurate mind map of the stars is all very well, but it is still a mystery how these ancient and courageous seafarers calculated their position of longitude. There are many theories of course, as there always will be in matters of this nature. One, which would seem to hold water better than most is based on the premise that back then, there was very little else in the way of man made distractions to fuzz the focus of a clear mind.

Metal was not widely used, and there was no radio disturbance, electrical appliances,
motors of any kind, or any of the other mechanical or electrical devices known to man today. Not having any of these distractions cluttering up the ether, our navigators and people in general were far more closely aligned with nature. So much so, that it is theorised that a natural man, standing in the fore peak of his craft, or lying in the bottom/bilge could actually sense the magnetic fields of the planet, drawing him on to wherever there might be land, somewhere in front of his vessel.
In addition the master mariner used all other resources to hand such as the wind, stars of course, wave direction, currents, swell movement, flotsam floating by, bird flight habits, other sea life and many other natural phenomena that was available to him.

They also carried frigate birds on board for use when they estimated landfall maybe not too far away. Frigate birds cannot get their feathers wet as they cannot fly wet, so on release they flew in the direction of land or, if no land in sight over the horizon, they would return to the canoe - hence the frigate bird image in the centre of the 'star compass' shown.

Noon clutches the sun precisely at its zenith – one minute before and it is rising yet, one minute after, it is already on its way down and setting. For practical purposes, the closest to noon a sight can be taken the better, but a minute or two either way can be allowed for in the subsequent calculations. Many things can get in the way of capturing the sun in the mirrors of the sextant, and tamed, dragging him down to the horizon exactly at midday – mirror not adjusted correctly, clouds over the sun, a sudden lurch of the boat, fumbling fingers – all can impede, and once done their mischief can take a few moments to salvage.

Our stalwarts manage a good sighting, with the lower limb of the sun, drawn down, lightly kissing the horizon, straight off. Notating local time and GMT(UTC/ZULU), they race below to fix their position. Until recently these calculations were made by using a complicated set of ‘declination tables’ and took some time to arrive at an accurate answer. Apart from this, they were bulky and heavy. With the arrival of the space age which has given us GPS, it has also brought us a astro navigation calculator which, with a few simple paths to follow, will give an accurate position from the information gathered up on deck.

Our crew race one another to punch in this data, read off their results and then compare them with the GPS, which of course is one hundred percent accurate. To their surprise, they are within 1.5 to 2 nautical miles of the GPS position stated. This is very good and certainly good enough to know exactly where they are at any time on the oceans of the globe. With a certain amount of glee they pronounce that tomorrow they will get even closer.'

Extract from my ebook 'Voyage of the Little Ship 'Tere Moana'

An interesting website dealing with this subject in more depth is 'Polynesian Voyaging Society'

You can read more about navigating under the stars in my ebook 'Voyage of the Little Ship 'Tere Moana' downlaodable from my website

1 comment:

Sailing Luckyfish said...

Great work. You touch on 3 great periods of navigation: Asian/Polynesian/Micronesian colonisation of the Pacific using "celestial objects, sea surface state, sea temperature, natural observations"; "celestial navigation" referring to use of sextant, tables and chronometer; and Satellite aided ("GPS"). The advent of positioning our own celestial objects to navigate by is inarguably the greatest leap by man, but also our greatest vulnerability should the former methods be forgotten.