I'm in Maryland in an unheated garage and I've used heatlamps to extend my build time into November. I find, though, that it's really no fun for me to be building beyond that, probably because of being raised in the southwest. I don't know if a hardy Yankee would just shrug those temperatures off, but for me it becomes problematical working on a boat in heavy clothing. So as Thanksgiving approaches, I put away the boat stuff hibernate til Spring.

Laszlo

I'm in west central Wisconsin, about 20 miles east of the Mississippi River south of La Crosse.

Winters here can be intimidating at best but having grown up and lived 200 miles south & east of here not far outside Chicago I'm inured to the climate. I have a friend just south of Danbury CT so I keep track of weather there pretty consistently. Winters there appear much less dreadful - both in extreme temperatures as well as duration of seasonal lows - and the lows don't last for weeks on end either.

When wife & I moved here six years ago the basement was a big plus (though it took me two years to suss out how to get it to stop taking on water when it rained hard during the thawed months here) for my tools.

Then the Waterlust project was announced. I put aside my long-held goal of an Oughtred MacGregor in favor of a Waterlust of mine own, complete with two masts and a Mirgae drive.

Not gonna happen in the basement though so it's my half of the 2-car garage for a birthing loft.

I considered having to make do with lamps & maybe a space heater but instead opted to insulate and drywall the garage, even going so far as to add a garage heater fueled off the natural gas supplied to our forced air furnace. I'm fortunate to be sufficiently skilled as well as motivated to do the work myself but it took time.

Depending on how well built your garage is you may be able to make do with heat lamps. Maybe a space heater too, but if your electricity is as spendy as what we pay for kWh here you'll want to limit its usage; 1500w running 24/7 at $0.16/kWh will cost you about $6 a day, likely not do much to keep your space conditioned to 60°F when it's 20° outside. With heat lamps you can direct the radiated heat at the area you're working on; a 125w lamp run 24/7 at that same $0.16/kWh costs about $0.50.

One practical approach is to 'tent off' your building space so as to make the air volume smaller. Use the air around the outside of a polyethylene sheet tent for insulation while you work inside it in relative comfort. In your climate (I think not quite as harsh as here in WI) that just might buy you a month on either end of your no-work extreme winter season.

MAS does not recommend using Slow hardener below 50 degrees.  I wetted out the entire hull of a Peeler skiff last weekend in Connecticut in a 60 degree garage and the Slow hardener worked fine...  hardened up nice after 2 days and the pot life was practically forever.  The mix was a bit thick...

To work in cooler temps simply pick up a half gallon of Medium speed hardener.  The MAS cure chart goes down to 41 degrees and shows a 52 minute pot life and 12 hour thin film set for the Medium.   This is exactly what I am doing to continue work on the Peeler.  I'll keep the garage at 50 to 55 and the Medium hardener will perform similar to the Slow at 70 degrees or so.

With the lawn choirs winding down and day light getting short what better way to keep yourself amused then building your boat!

   Any savvy Northerner will not waste precious water time messing with epoxy. Nice days are for sailing. 

"Any savvy Northerner will not waste precious water time messing with epoxy. Nice days are for sailing."

Maybe so, but... if you're not into ice fishing or ice boating, those months when the water's frozen 8" - 15" deep on all the water where in the other months it's fun wetting a hull on... you're happy to have something to look forward to... even if it's not your last batch of epoxy setting up enough so you can scrape the drips off before the next coat.

At 70+ years now I'm just not into wetsuit-sailing, thankyouverymuch. 

Most significant concern I worry over with workroom temp & epoxy is getting work conditioned to optimum temperature  so that wet-out – whether bare wood and filleting mix or first layer of 'glass+epoxy – to ensure thorough wet-out.

Next would be proper temp for mixing & application; the former can be handled by keeping unmixed components in a tempered space, the latter depends a lot on temps of workpieces. Which falls under workplace temp management.

Once stuff's well-mixed then applied so that wet-out is easily achieved, the cure depends on selecting appropriate hardener for anticipated conditions then appropriate workplace management. Too cool might slow down cure rate (assuming optimum temps aren't achieved) but too cool for the workpiece may seriously affect wet-out as the mixed epoxy will cool fast once application begins.

I look at the process as a ballet - set the stage for a command performance so you get the best out of both the materials and your efforts in making putting them to best use.