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From: (no name) (no email)
Date: Fri Nov 05 2004 - 14:26:31 EST
Quoting Wally <>:
> the buoys are numbered so if you should lose track of your position,
> it's a simple matter to re-locate yourself by finding a buoy. The key, of
> course, is to have current charts.
> The GPS can help if you use it as you said - to find out where you are
reply
ONE CAVEAT!
And this is not limited to Georgina Bay or any other particular place.
TRaditionally, charts wer made to server commercial shipping. Therefore, most
of th echarting efforts wer concentrated on commercial harbours, direct
shipping routes from A to B and so on.
Nav aids are placed to assist in this direct route that takes the least amount
of time.
BUT!!
When we go crcuising we often seek to go into the out of the way places where
we have some solitude or at the least is far away from civilization.
Even now these area have received the least amount of attention from the chart
makers. In Georgina Bay ther are numerous bays which are simply shown as blue
but blank as far as depth and underwater details are concerned.
This is similar to what you find in many other places.
Private groups such as the Great Lakes Cruising Club, private publishers of
Crusiing Guides like the one Wally writes for often provide moire and better
information than the official hydrographic offfice publications.
Unfortunately, the hydrographic office has until now been very reluctant to
accept data from such sources and incorporate them into the official and
certified accurate charts. Therein lies a problem.
All chart plotters use data from the hydrograhic office.
So if it isn't on the official paper chart you won't find it on the e-charts.
An additional problem can crop up with products such as C-Map and Navionics.
Their data processing is done offshore in a central office.
The work is done by people who have never been to th earea and who has no clue
what it actually looks like.
Occasionally errors creep and remain uundetected despite efforts at quality
control.
I found two nav aids located east of Giant's Tomb when in fact they should have
been located just east of Beauseleil Island several miles east of the Tomb.
I also found names mis placed for several islands. Despite reporting these
errors to the company the errors remained for several future issues of their
chart chips.
Mistakes also crop up in the official charts. Which is why periodic revisory
surveys must be done. Due to budget constraints these revisory surveys for out
of th way places may not take place for a decade or more.
I recall one preliminary Notic to Mariners dealing with a suspected shoal
located just outside the Wye Heritage marina. It was 10 years before a revisory
survey finally put that report to rest by proving the shoal was not there.
A USCG cutter struck a rock located about a quarter of a mile away from their
base. It had remained undetected for many years simply because no one had
struck it previously.
This is not meant to scare anyone but to point out that blind faith in any
technology or system is unwise.
regards
Arild
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