Hello Henry,
I have never heard of any inner wood planking on casemate bulkheads as being anything other than verticle or horizontal either until I read Farragut's engineer's report. I wonder how the diagonal 2 1/2" boards were fascined to the verticle 13" pine beams? The big bolts holding on the armor plating would not be close enough together to anchor all the little 2 1/2" oak boards. Do you reckon they were screwed on or maybe the big bolts with their nuts and washers holding the armor on also pinned down the diagonal boards with some sort of iron strips? Just a thought.
Dave