Jen-in-Wellies

I did it the other way round. Kept the brass runners and replaced the brass sliders on the hatch with HDPE versions. No help for the OP, but it is an option. A friend had access to a machine shop at the time and copied the brass ones using HDPE rod. HDPE has almost as good friction characteristics and is safer to machine than PTFE, while being cheaper to buy.

Welcome to the forum. Calling @Sir Nibble

Please refrain from debating the humanity of users on the forum. A report has been raised and the moderators are investigating.

Well spotted. However, @IanD has pointed out that a diesel generator is likely to be essential for some long tidal passage to avoid running out of juice.

In addition to the design features @Tony Brooks goes through above, I'd add that it needs a sufficiently large skin tank that the engine won't overheat when being worked hard. Narrowboat engines get an easy life crawling on the ditches, but hours at higher power on a long tidal passage will show up any lack in cooling capacity. The tidal river Trent causes cooling problems on narrowboats regularly. Cleanliness of the fuel tank is also important as part of the boats regular maintenance. Any water, or sludge in the bottom of the tank is usually not much of a concern, other than as a breeding ground for diesel bug, but in a swell, it can get disturbed and sucked in to the supply pipe. Eventually this will overload filters and water traps, stopping the engine.

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.