You can go to Lake Ontario via the Trent Canal with mast down if you draft is no more than five feet. Going the Welland Route should take you 10 to 12 days at a relaxed pace. From Oswego, NY where you enter the canal is about 8 to 10 days, again not rushing but moving each day. It is a very pleasant trip.
Heading back to Lake Ontario for this summer. Relatively few stops along the way from Grenada. Martinique, Guadeloupe, St. Martin (must have something to do with the French food), then Bermuda, New England and up the Hudson/Erie Canal. We were going to go via Newfoundland and Labrador but June remembered that one of the kids is getting married this summer - details, details!