Trip planning question

I don't know how much time you'd need for a trip like that . . . but they say that the 750 mile triangle loop (Troy Locks to Buffao along the Erie Canal) and Buffalo to Montreal along Lake Ontario and Montreal back to the Troy Locks through Lake Champlain takes at least 30 days in order to be enjoyable.

Trip Planning

Oswego New York to Montreal 160 nm
Montreal to Quebec City 140 nm
Quebec City to Charlottetown P.E.I 580 nm
Cansol Straights to Halifax 175 nm
Halifax to Boston 380 nm
Did that trip last year on 74' Viking Sport Fish 25 knots. It is a very nice trip, but approx. 1200 miles longer than taking Erie Canal.

how long is the trip from just oswego to new york?

Way too long and aggressive trip for a newbie. It'll also bore you to death and maybe scare you to death as well. You could get into a lot of trouble on the stretch from the Cape Cod Canal to the Straits of Canso, and there's really no place to go in once you leave Maine. There's also not much to see but ocean and more ocean.
I'd suggest you try something less aggressive and more scenic. Come up the Hudson to the Erie Canal, to the Oswego Canal, Lake Ontario up to the St. Lawrence and enjoy that area if you have the time. Then back down the Champlain Canal and you'll cross your wake at Waterford. Still have more time? Make a left at NYC and head out L.I. Sound to Nantucket, Martha's Vineyard, Etc. That cruise could easily consume an entire summer or more, and you'll probably never get seasick.

About 5 days through the canals, then a day to three days down the Hudson depending on the speed of your boat. Keep in mind though that there's two ways to cruise, delivery (get to your destination ASAP) or enjoying the trip (taking in the scenery and enjoying some of the towns you pass along the way).

I've always made it from New York City to Oswego in 3.5 days. 1 day from Manhatten to Troy, NY. Second day to the redneck yacht club in St. Johnsonville, Third day to the marina on the west side of Lake Oneida or Sylvan Beach, then Oswego by noon......I've made the Welland Canal in 4 days from Manhatten twice. This is running during the day and stopping everynight before dark and obeying the 5 mph area's of the canal system. These are deliveries.

I've also made it from Fort Lauderdale to Port Washington, WI in 14 days, only cruising during the day.

However, in a trawler doing 8 knots, you're looking at every bit of 5 days if not 6 days to get from NYC to Oswego.

Note from many of the responses the way to do this trip is clockwise, going out the St Lawrence.

But really what is the point of it? There is so much to see and enjoy along the way, making it a grueling go go go type trip seems almost criminal. I did a big chunk of the Canadian section including virtually all of the Maritimes with a buddy on his 42 Hatteras LRC, a 7 knot boat. I would love to do it again in my boat, and take a few months like he did (looped from Newport RI). I've done almost all of the US part in my own boat, which we run about 9 knots. I don't understand the comment about it being boring and "all ocean" one bit.