Frequently asked questions and other snippets about NavPak.
These fragments were clipped from email with registered users of NavPak.
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  We are actively building up a library of DMA charts, scanned whole in
monochrome, which will offer worldwide coverage.  We will be producing
CD ROM s' of chart collections for various geographic areas.  These will be
archives of charts scanned by registered users of NavPak, and our own
collection.
 
  For my boat, I'm planning to install a 10" monitor in the bulkhead at
the nav station.  I will be able to see it from the helm through the
companionway hatch.   I don't intend to leave it running in real time,
but would rather use it as a position finder at sea, and for approaching
land at night.  I try to get offshore after leaving a harbor, if it
doesn't send me too far out of my way.  
  Laptops need to have a secure, dark, dry place on a boat.  With a monitor
in the bulkhead, all you need exposed is a cheap keyboard and mouse.  The
rest of it can be standard PC clone parts tucked away in a cabinet nearby.
The CRT screen has higher resolution (1024x768) than the laptop (640x480)
which will make a huge difference for navigation by giving a better overall
view without loss of detail.

  "Offshore" magazine, June 1995, has an informative article about PC chart
plotting.  

  The two main bottlenecks in PC performance are both related to display
speed.  The actual computer time spent on navigational computations is
relatively minor.
  The first bottle neck is displaying raster bitmaps.  This operation
requires moving large amounts of pixels around and is best assisted by fast
CPU speed and lots of RAM. 
   Displaying vector images is dependent on the computational power
of the CPU, and will show a noticeable improvement with a Pentium.  A math
coprocessor will show a noticeable speed gain over a computer without one.
   
   NavPak uses a vector format as an overlay, on which you can draw your
own maps as a Windows metafile (.wmf), but we don't have a data base of
vector charts.  When vector charts are eventually available from National
agencies then we will eagerly support these formats.  We just received
the USGS vector world map info and source code.  It is expected that
NavPak will include support for this, but we can't say how soon.

  The capability of drawing and plotting lines is particularly important in
remote areas where charts are based on very old surveys, and it's necessary
to verify relative position on the chart with compass bearings.
  It's easy to get good bearings with a fluxgate compass, but it's hard
work wrestling with parallel rules in a rough sea.  This is where a chart
plotter can make things easier and more accurate.  When considering a
navigation program, look for the capability of plotting lines on the screen
to triangulate bearings.

 Raster charts are not ideal, but they do look good and are easy
to make.  We will be looking forward to a government vector data base.
Since the  chart inventory of all the national hydrographic agencies is
of questionable accuracy,  I think they hesitate in vectorizing it.
Sort of like throwing good money after bad.  Eventually we will see some
kind of government vector nautical charts, but it could be a long way off.

  The markers can be changed using a resource editor.  This is  part
of a Windows software developement kit.  I use Microsoft Visual C++ but
you could probably use Visual Basic or Borland C.

 I've observed bizarre behavoir from my computer after installing and
uninstalling alot of different software programs.  Many programs have
installation routines which make changes to system configuration files.
In all cases, I've been able to clean up the mess by reinstalling DOS
and/or Windows.  As a result of that,  I don't use any third party
utilities such as memory managers, video drivers, or desktops.

  National hydrographic agencies distribute charts of more than 20 datums,
and rumor says some of unknown datum.  I find that believable since national
hydrographic agencies  put their name on charts drawn by other agencies.
When the Admiralty and NOAA go digital, I don't think any effort will be
made to conform the charts to a common datum, but datum shift values will
be given when known.

  Color is necessary for wide acceptance by the general public, and helps
to find and decipher info on the chart, however For raw practicality,
it's hard to beat the monochrome bitmap.  Its  shortfalls are lack of
color, and  changing a chart to monochrome is considered a modification
of the data, and therefore would not qualify it for some regulatory
requirements.  I've noticed that using a pattern fill applied to the land
areas is a dramatic improvement.  I do this to my bitmaps using Paintbrush.
The pattern fill almost gives the appearance of grayscale without the huge
file size.   I've noticed that some of the old USGS charts without a Loran
overlay look excellent when scanned in monochrome, but the best solution is
color when baseline hardware gets better.

 It sounds like your bitmaps are color or grayscale.  They may not look
color, if scanned from a black and white chart,  but would have the large
file size of a color image.  The way to find out if they are color files,
is to load them into Windows Paintbrush.  If the palette on the bottom of
the screen is color, then they were scanned in color.  In this case, you
can save them under the same name as a monochrome .bmp file.  See "File
type" in the "Save as" dialog box in Paintbrush.

 We consider it a good marketing strategy for registered users to have the
latest copy, and makes customer support easier for us, so the upgrade cost
will always be low.  At present we charge $US 28.00 for upgrades.

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