There are all sorts of shapes and sizes. You can fit it out to have just about as much headroom as you like, but at the expense of where you can take it. My barge is 55ft x 12ft with 6ft 3" headroom in the saloon and about the same in the wheelhouse, with the wheelhouse folded down the air drat is 6ft 9". I am on the Trent at Shardlow and this only gives me a few inches of clearance going through Nottingham or up the Soar, an increase of 3" to 7ft would stop me. So unless you only plan to cruise on waterways with plenty of room, you need to do some research to see how much height you have to play with.
