This is where we get to the custom furniture part. My clients (aunt and uncle) were split on the chair back design. My uncle enjoys lower back support, as do I. My aunt, not as much. The compromise was to make two captains chairs with a different back. This added several hours to the build, but also gave me the opportunity to push my skills and creativity.
I should note, this is some of the most technical handwork I've pulled off to date, so I'll attempt to explain as best I can. I know, pictures do most the talking. If your not adept with joinery terms, you may need to google a few terms.
Anyway, notice the captains chair below is glued up without the back slats. Well, in order to give some lower back support, the back slats are going to go all the way to the seat. So, I can insert the custom backslats later when I install the seat.