Hi, I'm contributing to OSM for almost two years now. After doing my hometown, I switched to neighbouring villages, after this I mapped during my holidays in various parts of the world and so on... you know how it is.

Then I started to sail and wondered about a free map to load on my chartplotter- hey- openseamap.org and freietonne.de are there to the rescue. After reading a bit in the wiki I realized that things on the water are a bit more complicated than "amenity=restaurant; name=Hofbrauhaus".
As true as it may be- the result is disatrous. To properly tag a buoy you have to tag something monstrous like this:

*OpenSeaMap-Tags*
seamark:topmark:shape=sphere
seamark:topmark:colour=red
seamark:radar_reflector=yes
seamark:name=Rostock
seamark:lon=012
seamark:light:signal:period=4
seamark:light:ref=LF-Nr 3448
seamark:light:colour=white
seamark:light:character=Iso
seamark:lat=54
seamark:category=major
seamark:buoy_safewater:shape=pillar
seamark:buoy_safewater:colour:pattern=vertical_stripes
seamark:buoy_safewater:colour=white; red
seamark:buoy_safe_water:shape=pillar
note=Ansteuertonne Warnemünde

Or, since we got two tagging schemes which seem to coexist in parallel worlds:

OSM-Scheme-Tags (from WIKI)*
seamark=buoy
buoy=safe_water
topmark=yes
topmark:shape=sphere
topmark:colour=red
radar_reflector=yes
name=Rostock
light=yes
light:signal_period=4
light:ref=LF-Nr 3448
light:colour=white
light:character=Iso
buoy:category=major
buoy:shape=pillar
buoy:colour_pattern=vertical_stripes
buoy:colour=white; red
buoy:shape=pillar
note=Ansteuertonne Warnemünde

This is impossible for a normal mapper to do. I'm well aware of the fact that the seamarks are wickedly complicated and that there are well known international standards for almost every possible seasigns. On the other hand does the current situation do absolutely no good at all:

To date I still haven't found out how to tag a simple navigational light that sits happyly on a small Island IN A WAY THAT GETS IT RENDERED IN OSeaM- is this really so hard to do?. I passed a couple of those during my sailing trips and would happily add them to OSeaM- but I simply can't. The founders of the project seem to develop a wickedly complicated data model which fits the international standards nicely, but on the otherhand is so complicated that I can't tag them propperly and need a specially designed editor (which I might add- doesn't exist!).
Come on, something like:
seamark=beacon
light=yes
color=white
...would be completely sufficient to describe the data I actually have. Since I passed most of them during the day I can't even comment on number of flashes etc. This could be added later (e. g. by adding tags like: lightperiod=5sek; lightsequence= flash, flashnumber=3 or etc.). Unless someone climbs up the masts, noone can tell you about the height, and until someone spends half a day on each navigational light, you would never know about light sectors and such.
Something like the simple datamodel above would be actually useable NOW. There was always the mantra of not mapping for the renderer- and the time told that this mantra was right- the renderers got better and better while the data model in OSM got more consistent over the time in a completely evolutionary way.

The Openseamap datamodel is completely top- down, nothing evolutionary- actually they tell you not to tag stuff right now, since the datamodel is not "there" yet. The bad thing seems to be that the OSeaM guys don't talk to mappers- what do we want, what data can we provide (There are quite some complaints in the mailing lists that they don't participate in the discussions.) So I feel kinda stuck now. Also we don't tag for the renderer, I do not even can tag after a certain datamodel consensus that as usually somehow evolved in the wikis, because there is none.
What is a sophisticated data model for if noone can actually use it- either because noone can collect the data, or because noone can use it because it is way too complicated.

Why not use a simple datamodel that people can actually use for now and build on that- this is how OSM works and how it became great.

So far I had to use the freietonne.de interface to enter my data since they have an editor that works, and they render my data. Since the freietonne data also gets entered in the OSM database, not all is lost for OSM.

There was much arguing going on between the two projects (OSeaM and freietonne) during the summer and I don't wanna take sides, mostly because I haven't read through all the mailing list archives- who knows who was right or wrong. I don't want to flame annybody, I really think all have the best intentions, but to date the openseamap doesn't render lights in Croatia. Looking at the map of freietonne, I see that it somehow works. Why doesn't OSeaM render the freietonne datamodel too- as many other examples in the OSM history have shown, both datamodels can coexist without interference, and both datamodels can be rendered just hte same.

My 5 cents,
Christian