Create ribs on a surface

what i would like to do is create 'ribs' inside the shell. i have created the frame lines and offset them. i would like to create an 'edgesurf' from the two curves. when i do that only one frame curve is paired with all the other offset curves. i had expected that they would do edgesurf in matched pairs. another unexpected outcome is the the curve output from 'sec' is 8 curves, the curve output from 'offset' is 72 curves. clearly there is something i don't understand.

i do appreciate help though, tia