I am about to laminate some strips of Douglas fir to make up two spars - a yard and a boom, both 8 1/2 ft long. Prime considerations are lightness and stiffness. The question is what glue to use, and whether the ultimate strength and stiffness are contributed to by the glue itself. Has anyone any views or experience?
Partly as a trial run, I laminated up four shorter strips (in a jig because a slight curve was needed) to make a support beam for the dagger board case in my T12. (I won't go into detail, but I decided to use the wood supplied in the kit for this purpose for a slight modification to the boat as supplied.) I used epoxy, and the result was extremely stiff - rigid in fact. How much of that result was down to the wood, and how much to the epoxy itself?
Alternative glues to use for the spars would be Balcotan Regular (I have an unused bottle), or Balcotan's successor Collano Semparoc 60 (apparently Balcotan isn't available any more). They would be a lot easier to use than epoxy, and much cheaper, if they would do the job.
In passing, I have used far more epoxy than was supplied with the kit, and will probably need to get still more - and it ain't cheap! What with epoxy coating everything to start with, some glass cloth-ing followed by the recommended 3 wet-on-wet coats of resin coming up later, and final fairing, one fairly gets through the stuff. Also getting a good squeeze from a joint is inherently wasteful, and I have (temporarily) run out of holes to fill with the cleaning-up left-overs. I've become canny about the amounts I mix, but it all adds up. That's why using an alternative for my laminating would be preferable if it will do the job, which is a 'squeezing-out-excess-glue' situation with a vengeance. I hope my epoxy economy (or lack of it) experiences are not just me !?