In building your first kayak, I still recommend using 1/16 inch to 1/8 inch thick strips in building your external stems. I reference Nick's book "The Strip-Built Sea Kayak, and Vaclav Stejskal, Ocean Kayak book on installing external stem using 1/16 to 1/8 inch strips. Again, using a heat gun with a patient approach and laying the dry fit/clamp set overnight will aid in a permanent installation. Having a little water spray bottle seems to enable me to apply a little more heat without burning the wood, but this is your choice. I just recently completed a "Simple Design kayak" with almost vertical bow and stern, and I install maple external 1/8 inch using the described techinque. It was amazing how well maple stayed bent after I let set overnight. Good Luck!