I am not a narrow boat person myself - no particular reason because I have seen many of the scenic stretches on foot and I love the canals - and some websites have not been kept up to date [2 August 2002]. I believe that the following route is possible but you do need to check first if you are planning to do it. Contact me if this is a problem. I am starting at Manchester with the description and going clockwise but, as it is a ring, it can be started anywhere and done in either direction.
Get on the Rochdale canal and follow it all the way to its terminus at Sowerby Bridge near Halifax in Yorkshire. [My South Pennines Journal under Yorkshire has a page on some of the most scenic parts.] At Sowerby Bridge you can join the Calder and Hebble Navigation and go by the short Huddersfield Broad Canal to the Huddersfield Narrow Canal.
This is the bit I am least certain about.
There is some fine stuff here, both through Huddersfield itself, still very like a 19th century town in many respects although its University is very much a 20th century creation, and through Britain's longest canal tunnel at Stanedge. Its vital statistics are 3¼ miles long, 638 feet underground and 645 feet above sea level. Follow the canal to Ashton-under-Lyne where it terminates and joins the Ashton Canal. This is only about 6 miles long but it goes down 18 locks to get to the Rochdale Canal in central Manchester.
Two of the canals followed here; the Huddersfield Narrow and the Rochdale have only been restored this century, the latter in July 2002 indeed. The restoration project was thought by many to be quite beyond the bounds of possibility.