I'm not sure how feasible it is, but is there any way of creating a wiki on the site that would allow members to add information about different sections of the network?
I note that Wikipedia has a consistent map structure on its site; something like that would be a good starting point. Then users could add notes about favourite pubs, beauty spots, unofficial moorings, etc. that would be of use to all.
A separate page for each main canal, with some separate sections for longer routes would allow people to look at relevant information before setting out, or while en route for those with mobile internet access.
Any thoughts?