Problem is that whilst more water is a blessing less bridge height will restrict many boats designed to cope with existing heights. Damned if you do, damned if you don't.
With a mere 1'9" draught, you could halve the depth without affecting me, but I feel others would soon get bored of self-dredging expeditions /forums/images/graemlins/shocked.gif
Just thought it would be interesting to think 'outside the box' and see what the reactions were.
I agree its a see-saw effect but I suspect the vast majority of boats could cope with a few inches less headroom - many do it already by having tilting tophamper.
Might be a problem with lockside heights though.......
I voted to maintain current clearances, I guess it could work for some individual stretches of river, but it would be like moving the chart datum at sea. Suddenly every reference book ever writtian would be out of date. Isn't there a bridge up Lechlade way called Tenfoot Bridge? it would become Ninefootsix Bridge /forums/images/graemlins/grin.gif