NavList:

David Fleming wrote:  Increaseing shadow length will not improve the accuracy.  As has been noted the accuracy is limited by the sun not being a point source of light. 

I think we’re talking about two different error sources here.  There’re the difficulties caused by the Sun not being a point source of light and also the difficulties in measuring the base and the perpendicular of our triangle accurately, even if the Sun was a point source.  Size won’t improve the former although it might make that difficulty more obvious, but it can improve the latter.  DaveP