I use two types of glue for building boats.  The main glue I use is slow setting CA.  (Cyanoacrylate, super-glue type adhesive).  I like the "Loctite Gel Control" type, as it gives you a bit of time to align the parts where they need to be, before they set permanently.  Here, I have glued the stems in their pre-determined location, at each end of the strongback.  I put a shim underneath each stem, to make removal easier once the canoe is done being planked.  I make sure the top of the stem is exactly 1/16" above the upper edge of the forms, because this is where the bottom plank goes, and it needs to rest on top of them.