nautical charts

After seeing excellent progress of the map on dry land I wondered about making charts for boating. There seems not nearly as much activity in this field.
I think I understand that errors in the map are much more critical at sea than inlands. Give or take a street or two doesn’t hurt much, it just means a detour most of the time, although accidents caused by blind trust to your navigation unit do happen, a missing reef on the other hand is a completely different story.

Nevertheless, having free electonic data available could mean huge cost savings to many since the electronic charts are hugely expensive (think of about 200 Euros and up, and covering IMHO not very much area).
Since you should allways have a paper chart as a backup anyways OSM could soon be a nice to have to show something on your electronic chart plotter. For sure frequent crosschecking with the paper chart is a must.
Over time I am sure that OSM could be better and more up to date than the commercial chartmakers- especially in areas that are not very busy. The data that went into some charts is sometimes over a couple of decades, if nor centuries old (not very common nowadays, but true nevertheless).

One source of information could be the public domain charts from the US cover the coasts of the US and huge areas in the pacific. If someone could set up these for an extra layer in Potlach or JOSM, people could start editing right away. Other out of copyright maps could be found too.

One chap imported all Irish lighthouses into OSM (it was in the diaries page somewhere).

I was told that there are many GPS tracks recorded on boats that might contain depth data. Although they might be usefull too, this data is not as interesting than the data on reefs and shallows, but naturaly there is not quite as much data for those areas ;).

Getting data for marinas, buoys and what not should be quite easy though. It could be done in the classic OSM style with GPS, waypoints and pencil and paper.
For a start, if someone could make a layer for copyright free/ out of copyright charts for the editors- it would be great.
I don’t have any programming experience- so I have no clue how to do this myself.

Happy mapping,


I just learned that the US charts are also available in Vector format- so, a direct import might be possible.

You can do all these things on your own, and you can help alot by enumerating things on the water. I started search on the wiki for pages mentioning water and found some which I have added to the Water feature Category .

Here is the diary you mention I think:

Idea is very good, but it will never happen unless some organisation takes responsibility for adding all changes in area. And I would not say that Notices to mariners come out seldom. They work like a clock. Every week. IMO would never allow using OSM unless there is such an organisation with responsibilities. And then we run into another dead end - who would like responsibilities if they dont get money for that?

You are not along in thinking OSM can be used to create see charts.

Take a look at the OpenSeaMap page on the wiki. There is much more documentation and discussion on the german pages.