I’m in Sweden nearly every year driving canoo on lakes. Most of them are not in the OSM map at all. Should I enter incomplete shorelines with natural=water violating the Map Features Wiki saying that only points and areas should be entered with natural=water?

Perhaps this is an example of a more general problem. There are many tables and discussions giving a mapping (in the mathematical sense) “object in reality” → “tagging scheme”. Shouldn’t it be “knowledge about object in reality” → “tagging scheme”. For instance: the end of a line representing a street may be the end of the street or it may be the end of tracked part of the street, but this difference is not represented in the proposed tagging schemes AFAIKS.

I think you should map the shoreline, even though it’s no complete, but usually you an map it completly using the Landsat imagery. Btw please use shop=canoe_hire, and perhaps something like landing=canoe… canoe mapping is cool.

Spot on; about “knowledge about object”, your example has been brought up many times, I usually put a “FIXME=survey or road not complete” in the end of such a road, there are other way to do this but AFAIK there is no standard.

My example of this is when you go down a highway and you come to a crossroad, you continue ahead but want to mark this cross road AND the city that is 10 km further along on that crossing road. there is no way to map that either. But it would be useful on so many levels to have that information in the countryside.

Oh, didn’t think about that possibility. I’ll try it.

Never hired a canoe, I always hire a house including a canoe.

But e.g. additional tags cannot replace a first place consideration of partial knowledge when proposing a tagging scheme.
But perhaps this problem is hitting me harder than others as I have many old usable tracks in storage since the selective availability of GPS was switched off in 2000 – and all of them were made without considering something like OSM

When mapping roads, and encountering junctions or when turning around while the road continues, I’ve usually added note=Continues NNW/SW/N or whatever global direction it continues. It’s mostly for my own use, but a strong hint to other mappers that some work remains to be done. If a good alternative tagging would be thought up for this, I’d use it, keeping the note=* free for other uses.

It would also allow a hinting layer like the no-names layer to be developed.

Also, for areas, like in your lake example, I would indeed agree that adding a partial coastline is better than adding nothing. With proper tags saying that work needs to be done. Same applies to landuse, where I can not always determine the exact extent, but only know one side of the landuse. What abutters tags were used for a long time ago. It shows that you have knowledge of a feature, but do not know the complete extent.

In Finland there seems to be most usual to draw small lakes as closed areas tagged natural=water. Bigger lakes, which would need thousands of nodes are done as natural=coastline
http://openstreetmap.org/?lat=61.6692&lon=26.4394&zoom=13&layers=B000FTF

There are pros and cons in using natural=coastline. Good is that ways do not get extremely long and hard to handle for the editors. The result looks also often OK on Mapnik layer. Unfortunately sometimes rendering leaves out some island (compare with Osmarender layer). Annoying for users who are mainly interested in using OSM data is that lakes made with coastline system are missing from osm country extracts and even if they were included they should be processed in special way because they are a collection of lines, not polygons.
Semantic problem is that islands made this way are actually nothing. The same apply if lakes with islands have been made as multipolygons. Islands are then just holes in the lakes, that’s nothing as well. I do not know if they should be taggeg as place=island of something to make them as own objects in the database. But perhaps when there is consensus about tagging the briddleways/footways/paths (dedicated for some odd usage) in the British islands people will concentrate on Fenno-Scandinavian waters and paths in the woods, tramped mostly by animals and berry pickers.

Additional note on lakes as natural=water vs. coastline: On garmin maps created by mkgmap natural=water appears as blue area on the display. coastline on the other hand is displayed a line and enclosed area is displayed with same color as the area outside. ie. coastline renders less nicely on garmin.