could you not just square off the inside curve to 90 deg angle with a grinder?
Already thought of that the U bolts are passivated with a Zinc outer coating, this will protect them against the Marine environment, taking this off would affect their resistance to corrosion........oh by at least oo say 30 seconds...lol!!
Seriously, I had thought of that one, but it is ridiculous to think that one should pay £3 odd for these things, then modify them to fit because the ends are not made correctly.
I'm going to try one next week and see if it tightens into the shape....it may be the answer.