Sharon's information is materially correct, sad to say. I have just telephoned Francis Martin, Responsable du UTI (Unité Territoriale d'Itinéraire) Meuse-Ardennes who tells me they are hoping to open the canal to navigation mid May 2020.
When I queried the length of time he told me (in far too fast French to catch all) that there is already planning to demolish the damaged lock structure costing some €300,000 and funds are available for the re-build. BUT, there needs to be study after study by all and sundry before work can start and taking three months. The actual work of re-building is due to take a month and a half. SO, when I said that represents some six months at maximum and asked why the rest of the time to May 2020 he said we are near the end of 2018, weather during the winter is an element etc. etc.
If they make the hoped for mid May 2020 that should make plans for that year to proceed...but with caution. Keep an eye on the avis à la batellerie. The current one is: N° FR/2018/08146.
...an article in a local Ardenne paper quotes local officials saying that repairs and re-opening of lock 21 on the Canal des Ardennes is expected to take until summer of 2020. Something to consider in next year’s route planning.