BA Nautical Charts

From: Jack Greenbaum (jackg@cache.crc.ricoh.com-DeleteThis)
Date: Tue Apr 04 1995 - 10:45:29 PDT


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To: wind_talk@opus.hpl.hp.com-DeleteThis
Subject: BA Nautical Charts
In-Reply-To: Your message of "Mon, 03 Apr 1995 19:03:53 PDT." <9504040129.AA09992@usc.com-DeleteThis> 
Date: Tue, 04 Apr 1995 10:45:29 -0700
From: Jack Greenbaum <jackg@cache.crc.ricoh.com-DeleteThis>

On Mon, 03 Apr 1995 19:03:53 PDT Will Estes wrote:
> Hey everyone, take a look at the detailed depth chart of the Third
> Avenue sailing area on Jack's home page, at:
>
> http://www.crc.ricoh.com:80/~jackg/3rd.jpeg
[...]
> Where did you obtain this?

This is a standard issue NOAA Marine Navigation Chart. You can get them
at West Marine. I have an even more detailed one at home (larger print),
I borrowed this one from a colleage who lives on his boat.

> Are there others like it for other sailing sites?

Yep. In the works. I have the same level of detail for
Candlestick/Oyster Pt., and I have less detailed maps for Crissy and
Sherman Island. I could get better for the last two sites, but hey,
these maps were free. I probably could get east bay sites as
well. What's holding me up is a systems issue. We have an 11"x17" 400
dpi 24 bit scanner, but the hose connecting it to the network is a bit
flakey. Sometime in the next month we'll be getting a better box, and it
will take me only seconds (as opposed to about 30 min) to move an image
over to my workstation. The image that is currently posted was my trial
run, and it was a pain.

For the geeks out there, the image I've posted has been color compressed
down to 256 colors with almost no loss of detail (on a CRT at least)
from the 24-bit image. If I remember correctly the full sized image is
still 400dpi, not downsampled. Being able to scan 11x17 at a time makes
picking out the interesting areas much easier. I used PhotoShop to add
the labels.

> Several points of note:
[...]
> - What are those giant circles to the right of the center of the
> shipping lane, marked 139-through-147?

Those are mooring points, I believe that they are reserved for use by
the Navy.

What I find most interesting is how quickly the depth drops at the
channel. According to the map it goes from ~6 feet at low tide to 50 in
a very short space. Go figure we get the biggest swells right at the
channels edge.

-- Jack



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