We did this a year ago. With landcruiser and motorbike. We carried our friend's stuff in our car. A lot of sand, if you stop in a wrong place you will be stuck, a lot of dynes. Took us 3 days to get to Atar. Take extra fuel. We also took extra fuel to our friend on a motorbike, it was needed. It was hard to find the starting route, but all the tracks leads to the same place, just follow the train track. We drove next to it, not on it. People who drove on it, got several punctures.
It was tough, but absolutely worth of it. Sleeping in a night, when its so quiet and no one around.
There are little villages on a way, we later heard that you were supposed to stop in every of those, we did not stop in one.
Safety wise no problem.

I understand the last fuel will be available at Boulenouar (See: OpenStreetMap)

Yes, when looking at the map one will discover some small settlements like:

Like here: OpenStreetMap

Inal: 21,17,360N 14,59,740W
OpenStreetMap

Tmeimichat: 21,14,330N 14,22,585W
OpenStreetMap

I understand there won't be any fuel available along the way.
Will I find a basic accommodation at one of the villages?
Will we get water there?

Cheers,
Wauschi

Just a note to say, as i don't think it has been mentioned, there is the original piste and a new piste 100mtr's or so south of the original one which has much less corrugations etc.

Just completed...had some entertainment joining at Bou Lanouar, did a bit of freestyle routing - the dune sections have some tricky bits but once you lose the urge urge to follow other tracks (there often aren't any...it's been windy) it's lots of fun.

You don't have to stop at all villages, but there are a couple of checkpoints with friendly officers at a couple.

One of those checkpoints, village about 2/3 distance, has a 'building' next to it with 'Auberge' written on the side...if that answers the accommodation question? I found a hollow in the dunes...just me, the camels, and the occasional train.

I was pleased and lazy to find extensive blacktop from soon after where the corner-cut from KM400 joins the Choum-Atar piste/road. Thanks Chris for the route notes, and also the book we've been following through Morocco....it's been entertaining!

You don't have any pictures or waypoints or anything you could post up do you? I'd be interested to see anything you've got as this has been on my to-ride list for many years. I've "done it" on the train but as it went by night I didn't see much.

Did I read correctly that the Choum - Atar part is now a tarred road rather than the sandy piste it was when I was last there?

Hi - sorry for slow, brief reply...internet in Mauritania not up to Morocco standard!

I got the wayponts from here somewhere - Chris Scott's pages from book, which I had a print of. He has also posted the waypoints in gpx or kml. [Edit: In fact, having bought Sahara-Overland and Morocco Overland, the waypoint files and other support material are available online directly, I don't believe they are posted on here after all...hazy memory! The waypoints themselves are not that interesting without the commentary which goes with them - "keep the railway on your North and pick your own route through dune sections (using railway if necessary)" would probably do as well as just the waypoints.

If you want to see my exact route, its on the tracker page here
https//www.veganwithoutfrontiers.com/tracking

You'll need a password at the moment for the map, message me and I'll send it.

Tarmac is not quite yet all the way to Choum, but if you take the corner-cut from the end of the dunes you'll hit the roadworks at the beginning of it...

Have fun!

As I understood it, what VWF meant is that when you take the shortcut cross-country from KM408 just after the last dunes and head SE towards Atar, at some stage before the original N1 piste on map below - you encounter a new road from Atar direct to Choum and eventually Zouerat (as mentioned here) where the Bab map shows the planned road.
There were always tracks here as it was a direct way to Choum (and the train) from Atar. The current N1 goes east of the ridge for Zouerat, avoiding Choum.

The railway today cuts a corner of the PFZ west of the ridge on it's way to Zouerat mines. But in the 1960s when PFZ was Spanish Rio de Oro province, out of spite (it's said) the French build a 2-km tunnel under/around the corner, rather than accept Spain's conditions to cross their territory. Probably the same reason the N1 goes west of the ridge. Google 'Choum tunnel'.
You wonder if the new road might follow the rails via PFZ briefly, or just squeeze through.
(Fyi, a pre-Islamic crescent tomb 3km north of the old tunnel's northern exit).