Maptech and C-Map are two commonly used suppliers of electronic charts.
www.maptech.com
http://www.c-map.no/

A review of one software package used with C-MAP charts can be found
here
http://www.sailing.dbsparks.com/product_review.htm

started a thread in rec.boats.cruising on the
free NOAA Electronic Navigational Charts.
I copied his original message below, but the replies may also be of
interest to you.

dave.enab..'s message
Here's a little follow-up on what NOAA is doing with the nautical
charts.

The NOAA Electronic Navigational Charts (ENCs) are available for free
download over the Internet. Weekly updates are also available for free

download. About 540 of these vector-based electronic charts are
available, and more are added as NOAA finishes them. They comply with
the International Hydrographic Organization standard S-57. The
download site starts at
http://nauticalcharts.noaa.gov/MCD/enc/index.htm.


The NOAA Raster Navigational Charts (RNCs) are also available for free
download over the Internet. Cumulative updates of Notice to Mariners
corrections are available weekly at the RNC download site. Nearly all
of NOAA's 1,021 charts are available. The RNCs are in the .BSB format,

and conform to the International Hydrographic Organization standard
S-61. The download site starts at
http://nauticalcharts.noaa.gov/mcd/Raster/Index.htm.


NOAA has also posted nearly all of its charts on the Internet for free
viewing using any web browser. These posted charts are updated weekly
for all Notices to Mariners. The On-Line Viewer site starts at
www.NauticalCharts.gov/viewer. This is a new service, and NOAA has
provided a "Click Here to tell us what you think" button on the site to

solicit your comments.


For those who are GIS users, NOAA is providing a free, on-line
translator to query the ENCs for selected feature categories, and then
translate and download those feature categories in popular GIS formats.

The service is called "ENC Direct to GIS", and the Internet site
starts at http://nauticalcharts.noaa.gov/csdl/...direct_new.htm.

end of quote

Hope this helps.
Dave



jabadoodle wrote:
So my brother bought a GPS receiver for comptuers. It's the Delorme
Earthmate LT20. It came with Street Atlas 2006 software. He bought it for
other uses, but we're thinking it might be fun & interesting to use it on
the boat too. I have an old laptop with the necessary USB port & cabability.

Question is: What nautical software charts are there and what are the
differences.

Mostly this is just for fun & interest for us. Our boat is only a 22 feet
and we already have a handheld GPS that does not have mapping. We don't go
anywhere that we *have* to have mapping, but still would like to play around
with this.

So are there any options for software charts that aren't toooo expensive but
would work, show depths, etc.

Oh, we boat on the Hudson (not too much need for GPS as you either go north
or south), will be on Lake George this summer (again not too much need for
GPS) and are also planning a little trip from Boston to probably Glouster
(GPS on the comptuer not necessary but that would be the most useful place
to have a map of for us).

Thanks,
Gary