Well, localized heat should work. Point an electric heater at the hull where you will glue. Keep it a few feet away so you won't over heat things. An hour later, glue it. Keep the heater pointed at the hull for another hour. You should be fine. Make sure you mix the epoxy at room temperature. Eric
This PL300 looks like it can do the job.
Wood & fiberglass applications. Good to apply down to 10 degrees.
All I need now is to find it. I have an inquiry into the company to see where it can be had. Stay tuned.
Note; I'm not using this for structural construction. Just a mounting plate for a Y-valve.
I've checked out several places that make cold temp epoxy and they are all stopping at 40 degrees F. Now that I think about this...what is 2 degrees C? About 38 degrees F???
We aren't seeing temps above 35 degrees F as highs for the day. I'm sure the hull is holding in the cold temperature lower than that. The spot I'm working on would be difficult to get a heat lamp on. since this is non stuctural, I'm going to try the glue. Good to 10 degree F.
If you expect temperatures to fall below that level try Gorilla Glue. (Polyurethane glue.) This is what I used to install the cedar ceiling on my boat last winter. I left a regular 100W work lamp on the boat overnight when the temps dipped into the twenties. I didn't attempt any gluing at lower temperatures. So far so good.