NavList:

Jackson McDonald Wrote: The mutineers allowed Capt. Bligh to take a sextant and charts

It’s now believed that William Bligh had slightly more equipment than he claimed to have had in his account of the voyage, but not a lot more.  One thing he definitely didn’t have was a chart.  He did it all with maths, memory, his general knowledge, which must have been extensive, and tables. When he was cast adrift from Bounty in her launch, it was probably assumed by both Bligh and the mutineers that he would sail to the nearby Friendly Islands and await eventual rescue by to next ship to pass, even if that was months or even years off.  It was only when the Friendly Islands turned out to be not so friendly that he embarked upon the voyage to Timor.   Although his navigational achievement in the launch was remarkable, he didn’t actually have much more to navigate with while he was in Bounty.

We know from Bounty’s log that in her Bligh was running three positions, one based upon dead reckoning, one based upon longitude obtained using the chronometer K2, and one based upon a longitude obtained using lunars, presumably as a time correction to K2 (we never see Bligh’s detailed calculations).

 In the launch, he had a compass, and they were able to fashion a log, so a most of the time he was navigating using plane (not plain) sailing.  To do this, it’s believed he had Hamilton Moore’s Practical Navigator and Dunthorne and Maskelyne’s Tables Requisite which would have contained traverse tables, or at the very least, sin and cosine tables.  These tables would also have had amplitude tables, and declination which would have enabled him to check the compass for a combination of deviation and variation at sunrise if the sun were visible.  He certainly had a quadrant and possibly a sextant so, with declination tables, he would have been able to get latitude at noon.  He was able to borrow Mr Peckover, the gunner’s, watch, which would might have given him an approximate and relative longitude until it broke approximately 2/3 way through the voyage.  As far as is known, Bligh didn’t attempt any lunar calculations during the launch voyage, either because he didn’t have the ephemeris, or it would have been too much trouble.

 Although he didn’t have a chart, he had his memories of Cooks third voyage, when as Master of HMS Resolution, he was second in navigation only to Cook.  After Cooks death, he was in charge of navigation, which was one of the reasons he was left with a huge chip on his shoulder when he received so little recognition and no promotion to lieutenant on return in 1780.  He also had access to a book of lat & longs of places en-route as far as they were known at the time (although they might not all have been very accurate) belonging to Midshipman Hallet, so he was able to restart his dead reckoning from the few occasions he closed land for which he also had the longitude.

 I have a couple of questions someone might be able to help me with.  I’d like to find out.  1.  Were one of the navigational tables which must have been used by Bligh in the launch and the set of lat & longs belonging to Mr Hallet one and the same document?

 2.  Is there any record of Bligh’s detailed calculations in the launch over and above those in his notebook?   Without them, he must have had a brain on a par with an early, top of the market, hand held calculator. 

 For anyone interested in Bounty’s log and Bligh’s notebook, I recommend ‘Fateful voyage’  http://www.fatefulvoyage.com/index.html   Dave