Talk:Tag:waterway=fairway

Problematic tag

This tag is a bad idea - not mapping this kind of thing in general but tagging it using the waterway=* key. The concept of normal waterways (river/stream/canal etc.) is completely orthogonal to that of a fairway. Many navigable rivers have a route marked with buoys - in that case the mapper would need to decide if to tag it waterway=river or waterway=fairway or to create two ways - does not make much sense. Better to use a different key. --Imagico (talk) 22:23, 21 July 2016 (UTC)

If you have a proposal to use a different tag? This is explicitly not meant to replace waterway=river or waterway=canal (which IMHO are clearly defined), but to making routing possible on lakes and seas where there is a) no clear routing (looking at OSM data) and b) a defined route for boats. --Mdeen (talk) 06:00, 22 July 2016 (UTC)

OK - we have three different concepts here:

• The waterway as a physical hydrographic feature, a river or a tidal channel for example.
• The route regularly taken by ships/boats, which is usually mapped as route=ferry.
• The buoys marking the channel.

What we are talking about is the last point - ideally this should be mapped as individual buoys but of course a simplified mapping like this route is marked with buoys on both sides should be possible. I have no specific suggestion how to tag this but it should not be difficult to come up with an intuitively understandable concept. --Imagico (talk) 07:53, 22 July 2016 (UTC)

I second the comments here, waterway=fairway isn't a good value. Mapping individual buoys as seamark=* and use route=* sounds better. Fanfouer (talk) 21:54, 27 March 2018 (UTC)

I agree with Mdeen and disagree with Imagico & Fanfouer. A fairway is emphatically not just the buoys. And it is not a route=ferry: the ferry could go many ways, but chooses that one for commerce and convenience.

The fairway is the path that is safe and/or legal for larger craft to take. Often it's marked by buoys, but not always: in fact it may be completely unmarked.

There are many reasons to mark this on the map:

• buoys may be far apart, and so the fairway is not obvious to small craft;
• small craft (weekend sailors using OSM?) may not be able to read the buoys, which are coded - but they absolutely must be mindful of the fairway;
• buoys may not be used at all, with ranges on the land used instead;
• the fairway may not be marked at all;
• on a river, there may be a one-way channel under a bridge arch, again unmarked.

Having such a waterway=* on the map would also be consistent with sea charts, which always mark the fairway/channel (and also their navigation marks). Eteb3 (talk) 11:36, 8 September 2019 (UTC)

EDIT Eteb3 (talk) 20:26, 8 September 2019 (UTC) IHO definitions for illustration: (Taken from S-32. Emphasis is mine)

Fairway: That part of a river, harbour etc. where the main navigable channel for vessels of larger size lies. It is also the usual course followed by vessels entering or leaving harbours and sometimes called “ship channel”

But IHO also gives

Channel: That part of a body of water (sometimes dredged) deep enough for navigation through an area otherwise not navigable. It is usually marked by a single or double line of buoys and sometimes by ranges. The deepest part of a stream, bay or strait through which the main current flows. See also strait.

Personally I would propose waterway=navigation_channel instead of =fairway, since this applies to large and small craft equally. That is, unless the seamark: prefix catches all IHO features, in which case we should use that. Eteb3 (talk)

We have already a tag for this

seamark:type=fairway

That appears not to have a wiki entry: is it deprecated? Eteb3 (talk) 11:25, 8 September 2019 (UTC)