For some reason despite not owning one I have alot of interaction with Canal Boaters.
They are always interested in information about places and services along canals and I was trying to think of the best way of explaining how the contribute and use Openstreetmap
Of course contributing is easy - I just recommend mapcomplete.org, everydoor app, and street complete (less so as its road related)
And then I recommend an App like OSMAnd to use Openstreetmap - But for Canal Boaters specifically - Is there any way they could use layers or searches, any tips, tricks or Apps specifically get information that would be useful for them or be useful if in a canal boat?
Osmand has a ship profile, maybe you have to enable it in settings. It plans routes on water, displays nautical signs on the map, etc.
There is also a Nautical Map View plugin, available only in the paid and foss osmand versions: https://osmand.net/docs/user/plugins/nautical-charts/