NavList:

BTW, I don't like calling these "emergency navigation" systems. That implies using a less accurate system for celestial navigation in emergencies whose only advantage is that they are compact so as to fit in a ditch bag. This seems to say that you use the most accurate standard system everyday, carrying the entire set of HO 229 in your small boat, and will  use the bastardized system only in an emergency. What we are actually talking about are different methods of clestial navigation, that just happen to be compact, but that should be used every day for normal celestial navigation, leaving the entire set of HO 229 at the dock. Most navigators have apparently shifted to using HO 249 to save the considerable space (and weight) of the ultimate set of tables, HO 229, and find the level of accuracy in HO 249 accptable for practical navigation and the Bygrave and Hav-Doniol (and others) provide the same level of accuracy in very compact forms. 

gl