NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Plotting charts: WAS: Re:
From: Jeremy C
Date: 2009 Nov 15, 14:53 EST
From: Jeremy C
Date: 2009 Nov 15, 14:53 EST
Plotting sheets are used in the middle of the ocean to provide a larger
scale plotting surface to do Celnav, ENav, and DR's at reasonable intervals
(say 1 hour which is the norm in the merchant marine). If we didn't have
plotting sheets we would have to plot these positions on the only available
charts for the area which are usually small scale ocean charts. Those
would be very difficult to plot on in increments under 4 hours. They are
never used where there is a possibility of hitting land.
We typically don't use universal plotting sheets, but rather the
pre-printed plotting sheets that are 3-digit charts like 923 etc.
They are Mercator projection with scribed latitudes and compass roses. You
turn them over when you use them in North or South Latitude. Meridians are
properly scribed, but unmarked so they can be used for any longitude that you
wish. They are also the full size of most charts and are much bigger than
the universal sheets.
Any photos I've posted of my Celnav work on the ship was plotted on these
sheets.
As soon as we get on a reasonably sized chart, we switch to that and leave
the plotting sheet behind.
Jeremy
In a message dated 11/14/2009 12:42:12 A.M. Eastern Standard Time,
pmh099@yahoo.com writes:
Looks like I'm getting into the habit of starting new threads lately...
I remember reading that this is what the universal plotting charts are for. Navigators can do their plotting on inexpensive paper without marking directly on precious nautical charts. In the end, however, don't you have to translate your fixes onto a real chart anyway? How do you not "ruin" a chart that way? Aren't there tables with removable transparent surfaces on which you can mark and erase and below which you can affix a chart?
On TV I saw vertical panels looking like plexiglass. Can anybody describe what they are for and what the procedures are?
Peter Hakel
From: James N Wilson <jn.wilson@juno.com>
To: navlist@fer3.com
Sent: Fri, November 13, 2009 8:43:54 PM
Subject: [NavList 10668] Re: AP terminology
That reminds me of a story Ed Ripley told me, where he was on a power
boat going up the California coast. He properly started plotting a DR
track, whereupon the owner cried, "You're writing on my charts!" So he
stopped. Later the radar went out, and they had no idea where they were.
They finally had to ask a fishing boat for that information. This, of
course, was way before GPS.
Jim Wilson
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