Jen-in-Wellies

Generally the folk by the cut with assorted substance and mental health issues are lovely.

Welcome to the forum. The canals in Birmingham just don't get the traffic. You were in probably the busiest part. The contrast with the K&A, probably the most travelled canal would have been stark. A shame really, as they are very interesting. Well done for going there. Brum does have a bit of a reputation, which isn't justified, as long as you take some precautions over where you moor. The lock flights to get up and down to the plateau also put people off, but they are easy to operate and generally better maintained than some flights on the system. Peaky Blinders hasn't helped the reputation of the BCN either. 😀

You could easily see much of the full weight of a hull repeatedly coming on the bolts and struts in various combinations of tensile and shear forces in a swell.

Totally off the wall idea and happy to be shot down in flames. How about two narrowboats? Use them as a motor and butty on the narrow canals, then bolt them together to form a catamaran for wider canals and the sea.