I have made that trip. You want to ultimately be in
Halifax by Oct first. If you've made ocean passages before this, then later works too. The latest I've left
Halifax is Oct 31.
St Lawrence is mostly a
motor, or
motor sail, as currents are much more of a factor than
wind. Once you leave the St Lawrence, the dominant
wind in summer is SW, which will
work fine for you to get to PEI or Cape Breton/bras D'or lakes, though a Norther is faster.
Eastern PEI is a nice
cruise with very pretty
anchorages, or if you prefer, go from the St Lawrence, and through the Bras D'or lakes (which is what I would suggest for it's pure beauty), then coastal hop to Halifax.
The trip to Halifax, if you want to make time, is best done during Northerlies, so a cold front is best. The wind comes off the land and the waves will be of no consequence.
From Halifax, if you're making time, again, cold fronts are your friends. If you're coastal hopping, then just sail when it's nice and you'll get there...
It's not a difficult trip, if you have some ocean experience. If you don't, take my
advice: A 20
knot forecast from the N or NW is far more pleasant than a 15
knot from the SW between the St Lawrence and Yarmouth.
From Yarmouth to
Maine is more of a Westerly trip, but watch the tides at the Bay of Fundy, the
current will carry you, and affect the waves too.
Some folks like sailing on pretty days, and hunkering down in an anchorage on crap days. Personally, my wife and I prefer to play at
anchor and tour the area on nice days, then hunker down in the
cockpit offshore on crap days. This way we can see the best of our destinations during the best
weather, and on crap days... well we wouldn't see anything at
anchor anyway, so why not move on?
Our cat has not yet launched, so the experience I have on these trips are on 35 and 39 foot monohulls, both with good dodgers, and the 39 had a nice
bimini too. Both boats had espar heaters, but you won't have any need for one between July first and the end of September.
Enjoy your trip, it's a beautiful way to see some of the Maritime provinces.
Cheers.
Paul.