[Tagging] nautical channels

[Graeme Fitzpatrick]

On 1 July 2018 at 13:59, <osm.tagging at thorsten.engler.id.au> wrote:

> Maybe following the same scheme as for highways:
>
>
>
> waterway=navigable_channel (for way along the middle of the channel)
>
> area:waterway=navigable_channel (for area bound by buoys, with an
> intersecting node at both ends between the area and the middle line way)
>
>
>
>
>
> The real question becomes: tagging as a way in the middle of the channel?
> Tagging as an area (by mapping the buoys as seamarks, then connecting them
> to form an area)? Both? Either?
>

I've been having a think about this idea & just can't decide what would be
best?

Would be easiest to just put a line up the middle, similar to a road, & say
"this is the channel", ignoring the actual width (which would be very hard
to determine anyway).

Obviously, tagging it as an area would show the width of the channel, but
do we just take it as a straight line from nav. marker to nav. marker, or
try to take into account any variations in width?

The problem with both schemes is what happens when the channel opens into
an area of safe water, in the way that a river opens into a lake. Do we
stop the "river" at this side of the "lake", then start it again at the
other side, & show the area of the "lake" as being part of the channel?

Whichever way, it will involve a lot of work to get it all correct, unless
we are able to copy details from existing nautical charts, with all the
associated copyright issues?

I'm actually wondering if this is something that should be in Open*Street*Map
at all, or whether it should be left in OpenSeaMap?
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