OpenSeaMap and Garmin nautical chart plotter

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Garmin logo 2006.svg

on Garmin GPSmap 7015
on Garmin GPSmap 526

OpenSeaMap worked for many years on chartplotters and most handhelds from Garmin.
A new management had decided in 2017 to exclude OpenSeaMap on chartplotters. Eine neue Firmware sorgt dafür.
But there are hints that you can downgrade some plotters to an old firmware version.


Maps of any region are created and made available for download within a few minutes by the following service:

Map sections (rough) of the maps of Europe

Use the following link to download newest generation OpenSeaMap of Europe. It works on chartplotters even with recent firmware:

Forum: and


Coverage is worldwide.

Characteristics of the map

When zooming in, you can see buildings.
When zooming out, the streets disappear and you will see an overview map of rivers and water surfaces.

Garmin GPSMap 526
Piloting chart
Garmin GPSMap 526
Harbour plan
Garmin GPSMap 526
Overview map

Tips & Tricks

  • Older devices may only support maps up to 2 GB.

Device list

Oregon 450

OpenSeaMap works on the following Garmin devices:
OK! = tested successfully

All these devices should work for OpenSeaMap, also all the hand-helds and chart plotters in this list:

ok Type Comments
OK! Echomap 50 dv Plotter with integrated Fishfinder
OK! Echomap 50 s Plotter with integrated Fishfinder
OK! GPSmap 7015
OK! GPSmap 7012
OK! GPSmap 6012
OK! GPSmap 6008
OK! GPSmap 6012
OK! GPSmap 6008
OK! GPSmap 5015
OK! GPSmap 5012
OK! GPSmap 5008
OK! GPSmap 4012
OK! GPSmap 4010
OK! GPSmap 4008
OK! GPSmap 720 / 720s Touch screen
OK! GPSmap 620 Portable two-in-one touch screen device for street and marine applications
OK! GPSmap 531 / 531s
OK! GPSmap 527
OK! GPSmap 526 / 526s
OK! GPSmap 521 / 521s
OK! GPSmap 421 / 421s
OK! GPSmap 172C No longer available
GPSmap 60 cx Outdoor
OK! GPSmap 60 CSx Outdoor
GPSmap 62 s Outdoor
GPSmap 62 sc Outdoor
OK! GPSmap 62 st Outdoor
GPSmap 62 stc Outdoor
OK! GPSmap 64 s Outdoor
OK! Colorado No longer available
OK! Dacota 20 Outdoor
OK! eTrex 10 Outdoor, by Mapsource + Multistorage (only 12MB)
eTrex 20 Outdoor
OK! eTrex 30 Outdoor
OK! eTrex Legend HCx Outdoor
OK! eTrex Venture HC Outdoor, by Mapsource
OK! eTrex Vista HCx Outdoor
Montana 600 Outdoor
Montana 650 Outdoor
Montana 650 t Outdoor
OK! Oregon 550 Outdoor
OK! Oregon 450 Outdoor with marine mode

Technical background

Over time, the various Garmin devices for car, outdoor and marine applications have evolved in different directions.

New maps are only compatible with the device for the respective target group. NT maps with lane assist guides and traffic information only work on Garmin nüvi devices, whereas the very detailed and colourful topographic maps are meant for use in outdoor devices. However, Bluechart G2 Vision only works in combination with marine devices. All sea maps, either traditional Bluechart, G2 or G2 Vision, work without TYPE files, as these do not display particularly detailed or multi-coloured images on shore. The Bluechart version does not offer green meadows, brown fields or even tree symbols in a forest. However, outdoor devices were designed to be used in a car or on a boat as well. For this reason, a partial support for NT and Bluechart (G2) was implemented. Unfortunately, they did not implement lane assist guides or Bluechart Vision.

So far, Garmin marine devices do not support TYPE files (for freely definable symbols, colours and textures). In order to display polygons, only a few clearly defined colours and textures are available. Without TYPE files, however, the priority of polygons cannot be defined. Maps that are displayed perfectly on Garmin outdoor or travel devices generally do have the same quality on marine devices and are therefore unusable.

Garmin has built in a locking mechanism in newer marine devices to prevent older Bluecharts (without G2) from being used (Message: "Karte nicht kompatibel" [Map is not compatible]). This lock also takes effect when OSM cards are involved.

Thus, a special OpenSeaMap chart was developed for owners of Garmin marine devices. It is particularly designed to adapt to the options of marine devices, which are rather limited compared to those of outdoor devices. This chart also works on outdoor devices with marine mode (e. g. Oregon) without any restrictions. It should also work for older marine devices. However, you should not download the entire map of Europa to less powerful devices in one go, but choose MapSource sections instead. Otherwise the image buildup will be very slow and there can be gaps in the map if the working memory is too small.

On devices that are exclusively used in cars (nüvi series) the map will probably not work without restrictions. Devices for aviation have not been tested so far. px