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Just read this (in Tom Sheilds - More Tom Shields' Diary Too (a collection of funny stories, articles and tales printed in 1993 and collected in part from The Glasgow Herald newspaper in Scotland)) and thought it was worth passing on...
It comes from a Scottish yachting paper called Wavelength and is "a brief description of position fixing while on the move by the principle of dead reckoning...written in simplified form"
Here it is:
"Dead reckoning can tell you where you are at any given time, and it operates on the principle that if you know where you were, and if you know where you have gone, then by extrapolating from where you were and where you have gone you can calculate where you are, or at least where you were when you originally started calculating. Since the position where you are now is not the position that you calculated, and the position you were in then is not the position you are in now, it follows that you have introduced the error (This is defined as the difference between where you are now and where you aren't, but calculated you should be). This error can be minimised by calculating your next position where you weren't but calculated you were, to the position that you now aren't, because you had just moved. Unfortunately, you still have an error but by this method it does not compound itself, giving rise to an accurate position of where you are not. If the wind and tide are not equal and opposite then a calculation must be made which takes into account their cumulative force and direction. It is important to remember, however, that the time interval is the time from where you were to where you no longer are. This calculation results in a correction that is to be applied to the position where you are not in order to accurately ascertain that you still are not. Apparently this is the same method used by Christopher Columbus when he set out to establish the existence of Australasia but discovered the Americas"
No wonder Columbus got it wrong
It comes from a Scottish yachting paper called Wavelength and is "a brief description of position fixing while on the move by the principle of dead reckoning...written in simplified form"
Here it is:
"Dead reckoning can tell you where you are at any given time, and it operates on the principle that if you know where you were, and if you know where you have gone, then by extrapolating from where you were and where you have gone you can calculate where you are, or at least where you were when you originally started calculating. Since the position where you are now is not the position that you calculated, and the position you were in then is not the position you are in now, it follows that you have introduced the error (This is defined as the difference between where you are now and where you aren't, but calculated you should be). This error can be minimised by calculating your next position where you weren't but calculated you were, to the position that you now aren't, because you had just moved. Unfortunately, you still have an error but by this method it does not compound itself, giving rise to an accurate position of where you are not. If the wind and tide are not equal and opposite then a calculation must be made which takes into account their cumulative force and direction. It is important to remember, however, that the time interval is the time from where you were to where you no longer are. This calculation results in a correction that is to be applied to the position where you are not in order to accurately ascertain that you still are not. Apparently this is the same method used by Christopher Columbus when he set out to establish the existence of Australasia but discovered the Americas"
No wonder Columbus got it wrong
