NavList:

Dale Lichblau you wrote: Frank Worsley's only problem on the James Caird was having two of the six person crew steady him and hold him when trying to take a sight so that he wouldn't tumble overboard. I believe that sextant is at the Cantabury Museum.

Last time I visited, about six years ago, there was a sextant on display in the Scott Polar Institute in Cambridge UK that was claimed to be the one used by Worsley in the James Caird.  I remember because in documentaries and drawings I’d not noticed anything special about the sextant, but the one at Cambridge was a whopper https://www.spri.cam.ac.uk/museum/shackleton/articles/y2010.75a/ .  Maybe they had two sextants.  Interestingly, the museum caption says Worsley used it ‘on’ the James Caird whereas a naval man would say ‘in’ the James Caird.  In this case, both are correct, because as you point out, Worsley was ‘in’ the James Caird most of the time but ‘on’ her while shooting the Sun.  DaveP