[Public-List] Charts and depth sounding

[R Kirk]

Don't count on fresh surveys.
The USA is similar with frequent chart updates. But the very frequent Weekly Notice to Mariners*   invariably just shows buoy shuffling. Even the chart reissues which are done after several years are merely reprints to replace the previous heavily pen & inked corrected versions before they become illegible. In no cases are the soundings changed from the last century's work - unless you're lucky. The few NOAA survey ships which are left service the Navy & commercial shipping interests. Local surveys that interest we sailors are contracted out, as budget permits. I'm guessing Canada is similar.
*My earliest recollections were of my father getting the weekly notices in the mail. He called it the "Boat sunk notice" because it reported the location of ships sunk by German subs off the south shore of Long Island early WW2. 


-----Original Message-----
From: Gordon Laco via Public-List <public-list at lists.alberg30.org>
To: Alberg 30 Public List -- open to all <public-list at lists.alberg30.org>
Cc: Gordon Laco <mainstay at csolve.net>; a30240 at earthlink.net; A30 Public List <public-list at alberg30.org>
Sent: Fri, Feb 18, 2022 8:13 pm
Subject: Re: [Public-List] Charts and depth sounding

Hello Jim, 

The Canadian Hydrographic Service continually re-surveys and updates charts through ’Notices to Mariners’.  This was once distributed by mail, more lately it has been available online, updated even more regularly.




Gordon Laco
www.gordonlaco.com





> On Feb 18, 2022, at 8:10 PM, a30240--- via Public-List <public-list at lists.alberg30.org> wrote:
> 
> 
> 
> Gordon wrote
> "My own opinion is that a depth sounder without a navigation chart is useless. The depth reading can be correlated with charted depths to help determine position? and THAT is what lowers the chances of going aground. Probably the most useful application of a depth sounder is when dropping the hook and determining how much anchor chain or rope needs to be let go.
> 
> Two months till sailing? wahoo?"
> 
> It might be worth noting that most charts, at least in the US for areas primarily used by small craft haven't been surveyed in a long time. While this isn't a major issue in places with hard bottoms, shallow water areas in the Chesapeake and along the US east coast haven't been surveyed in the lifetime of most skippers.
> Also just because you have the newest chart plotter doesn't make it more accurate than the government charts the data is drawn from
> Granted there is some updating when an individual or agency reports a change: dredged channel, bridge, marina, buoy location, etc.
> 
> Jim Davis
> Prairie Schooner
> 
> Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup
> 
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