First, a question, if I may, about your screen name, "ploschiavo". It is so very similar to the name of a small town in Switzerland near the Italian border, Poschiavo. Does your screen name have anything to do with that town?
As to hinging your arch, I wanted to do the same, for the same reason, when we purchased our DeFever 44. The arch on a DF44 is bolted to the inside of kneewalls. The yard doing our refit did not see fashioning a hinge as being nothing but more boat bucks. I had seen arches on other DF 44s with hinges. Unfortunately for us, when the yard unbolted the arch it was found to have been completely waterlogged (bad bedding of radar and antennae allowed water intrusion). It took four strong men to wrestle that arch off the boat. The point is, I believe it can be done, at least to some boats.
In our case, we chose not to have the now useless arch replaced with a custom-made fiberglass duplicate. The yard wanted way to much. Instead, we had Atlantic Towers of Bayville, NJ to make an arch from aluminum piping to the exact dimensions of the original arch ($2,200 in 2015). It must be lowered by two persons, one to pull the pins and the other to lower the arch which, by the way, is easily handled by one person.
As it turned out we did not end up going thru Chicago. We used the Cal-Sag Channel instead. However, we did lower the arch to negotiate the Champlain Canal. We chose that route to do the Loop instead of the Erie Canal/Oswego Canals route. But, in our case, we had to lower our bimini also which was kind of a pain, a bit more so than simply lowering the arch. Still, we were very happy with our choice to take the Champlain route. We don't know anything about your boat but the presence of a bimini may also be a consideration for you. Our air draft with the arch lowered and the bimini in place is 17 feet.
