Milling my own lumber in the pacific northwest

Building a catamaran designed in Europe while living in the US does present a particular issue.  Since the rest of the world stubbornly refuses to adopt imperial units, I am building this catamaran to SI measurements.  I knew this was coming and already had on hand a metric tape measure. I had to order it since stores here don't stock much of metric anything.

What also is not available in metric units is lumber.  Living in Seattle clear vertical grain douglas fir is easy to find, So I found 5/4" X 6" decking (actual measurement is 1 inch by 5.5 inch) turns out this rips nicely into 5 20X25 mm strips (actualy 20 by 25.4mm). For the 20 X 35 mm pieces I'm planning on using 1" X 2" (actual measure 0.75 inch X 1.5 inch) these will give me pieces that are less than 1 mm too narrow (19.05 Vs 20), but just over 3mm to deep (38 Vs 35).  I will ask Bernd if this is acceptable. I try not to bug him too much. So here are some pictures since that is what is really fun about a blog anyway.

Update: I did ask Bernd and within minutes he had responded that the 1X2 material is OK. See post for how I chose the 660 on Bernd's awesome support.