I''m not so sure I buy the part about metal v. plastic sextants, though I realize it is the common wisdom. You ought to check the calibration on any sextant before you try to take a shot, no? How much can the material expand/contract if you take your shot within a few minutes of correcting? I have a Davis Mk something (the one with the beam converger) and can shoot a sun/moon fix within a minute of arc, using the
GPS as a reference. I do agree that I want my electronics aboard as well; no substitute for a Celesticomp! ;-)
--Mike