NavList:

BTW: Did the Royal Navy apply redundancy? If so, in what way?

I think the Royal Navy did apply redundancy of sorts, but probably not to do with great circles.  In a square rigged sailing ship such as HMS Resolution or HMS Bounty you were very much limited by wind and weather as to where you could sail, so your chances of approximating to a great circle were pretty slim.  There was some redundancy in that almost everyone on board owning a sextant would be taking shots at the same time, but the juniors had probably been taught by their seniors, so they were probably using the same methods.  Also, there seems to have been a tradition in the RN that the captain is always correct.

There does seem to have been redundancy in position recording.  The log of HMS Bounty shows that Lt William Bligh recorded three longitudes, one based upon dead reckoning, one based upon astro using the chronometer K2, and one based upon the use of lunars.  Even after he was cast adrift in Bounty’s launch without K2, he recorded a longitude based upon plane sailing and one based upon astro using Mr Peckover’s, the Gunner’s, watch until it stopped working half way through his ordeal.

Then, when returning home in a Dutch packet, Bligh continued his own independent navigational log.  Imagine how popular you'd be trying to pull that stunt on a modern day cruise liner.  Dave