Custom GPS Maps

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I love using my Garmin GPS's with the mapping feature.

But even with the Mapsource maps, the coverage is lacking outside the US, UK, and Europe and outdated even in the US.

Example Captured from GPS screen, showing Cozumel, QR, Mexico

Americas Basemap:
Permanently installed in GPS
if purchased from a dealer in the Americas.
  • Shows the rough shape of the island
  • The International Airport
  • San Miguel (city) not by correct name
    (covered by F3 waypoint)
  • Cedral small town
Worldmap Loaded:
  • Shape of the island is slightly better
  • A few streams added
  • All 3 light houses are shown
    (W) means light house
  • Several water navigational lights (red or Green)
  • Only 2 roads show (as unpaved)
    funny, 10 years ago these and a lot more roads were paved, not to mention a lot more unpaved roads
My Custom map Loaded:
  • Accurate detailed outline of the island
  • Mangrove North side of Island
  • Main Paved roads (runs across and around south and back to San Miguel and to the mangrove)
  • Many unpaved roads (looks like rail road ties)
  • Many residential streets in San Miguel
  • Airport shows both runways (CZM commercial, and Military)
  • 100 Meter depth contour shown around the island.
  • Points Of Interest: Carlos n Charlie's (bar), a few Hotels, International Port, underwater Wreck

I created this Map while learning how to create them, and plan to add much more detail over time.

None of the data or images were used from any Garmin map product to create My Custom Map or upload to the GPS. Screen captures are shown for comparison only.

My Cozumel Marine Map

My Cozumel Topographic Map

The same map loaded in a COLOR GPS (GPS map 76cs)
Testing Accuracy of Maps

On my recent cruse to Cozumel & Calica I was able to use and test the custom maps.

Click for large view
The waypoints show that the map is correct, but 500 ft. too far north of actual positions.

At Calica the ship
backed into port.

Click for larger view

Click for larger view
Here the Dregged
Deep Water Port is clearly seen on the GPS and in the Photos I took.
I have marked on the photo where the waypoints were taken, very accurate!
    The wandering track lines were made while I was doing extensive research,
Click for larger view
under the cover of a tent and GPS in a less than perfect position for satelite reception.

More Maps I have made

Here is another example of a Mountain Bike Trail in Mexico.
Included are 2 mountain summits that can be found in the Points of Interests
QR Mexico
S W Yucatan
Topo 1:250,000
First Monday Market
Canton, Texas USA

Bluebonnet Park
Ennis, Texas USA

I Gathered the park data with
a GPS & Mountain Bike
Topo 1:24k Plus

For all the maps I have made see My Custom Maps

UMP extra help on step #3

See GPS Sendmap to send my custom maps to the GPS.

More links to GPS here

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This page written by DougsBrat ©2003
and updated on