Many locks on the narrow network can take boats up to 70 - 72 ft in length, but some locks are shorter, particularly on the Leeds and Liverpool Canal, and there are some tight corners.
A length of 58 - 60 ft (17.62m - 18.22m) would be more suitable for cruising the whole network.
You will also need to bear in mind that boats wider than 7 ft (eg. wide beam boats) won't fit through narrow locks. Take a look at different types of boat.
Waterway dimensions of many waterways are available on the Waterways Information pages of IWA's website, by enquiry to the appropriate navigation authority.
If you are having your own boat built, your builder will also be able to offer advice.
Browse individual waterway pages.