timkent: Controlled depth in the Oswego and Erie Canlas is supposed to be 13 feet, but our experience going through in 2000 suggests it is less in spots. Since you are so close to the limits, I would call the NY State Canal Corporation at 1-800-4CANALS and get their guidance. Otherwise, you''re looking at going via the St. Lawrence which is about a thousand mile detour if you intend to continue south from New York.
With a 12''-3" draft, you''re going to have to make sure you use the shipping channel in Lake St. Clair, because you won''t get across otherwise. Out of curiosity, what kind of boat is it that has such a draft?