 As the navigation had fixed bridges, sailing boats needed to be able to lower their masts, and this prevented sea-going boats, called flats, from using the navigation, as they required the extra rigidity of a fixed mast.In the early 1760s, a new cut was built between Sollom and Rufford, and fixed bridges began to be replaced by swing bridges.A new lock at Sollom was a little further downstream than that at Crostons Finney, resulting in access to the navigation being possible on more days each month.