OK - here are a couple of things. I have found your Alexander Croal (m Mary Park) in the 1861 census - he and his daughter Mary W. are in Dundee St, Barry - under Croall - he is retired. (But maybe you have that and just haven't put it in your tree).
Now I may have found the birth of Isobel Whitton - there was one baptized on 20 Dec 1759 in Barry. Her parents were James Whitton and Agnes Small and there abode was in Whinny-hall, parish of Monikie. (ditto about the tree).
How sure are you of the dob of John Croal in 1765? Isobel would be some six years older than him, which might be a bit unusual. By the way John was a mason by trade.
Now there was a John Croll baptized on 5 Apr 1758 (which would make him more Isobel's age) in Arbroath to James Croll and Mary Petrie (one witness was David Petrie who could be her father or brother perhaps). Now, they also had several other children, one of whom was named Alexander who was baptized on 7 July 1760 (David Petrie was a witness).
What I like about this family is that if this John is your earliest John, then my earliest Alexander Croal, ship master and father of my gg uncle Alexander Croal born 18 Jan 1801, could be his brother (who married Jean Laurance). I'll see if I can dig up anything else on this.
As it stands at the moment, my first Alexander and his son Alexander who married Susan Raitt (and drowned in 1875), do not appear to be otherwise related to your Croals unless my speculation above is possible.
Now, turning to the master mariner side. As I mentioned earlier, I have come across various certificates of competency of Alexander Croal. Looking at them more closely, I think that records may have got muddled and are incomplete. The master's certificate does belong to my Alexander Croal I believe because even though the year is incorrect, the actual date of birth is correct - and you might remember your day rather than the year perhaps! Records of service also tie up. The certificate was granted in 1851 - yet there was an announcement in a London paper that Alexander Croal had passed his master's exams in London in 1850 and he was second mate on the Palmyr of London. Other records I found for justification relate to the Palmyr of Liverpool as well as London. Since your AC's family was in London in 1851, then this fits - especially as children were born in Liverpool.
I also note from your tree that the Hon John Croal was the owner of a plantation called Palmyra. I wonder whether he was the owner of the vessel that AC was aboard? John may also have been a ship's captain because in the late 1830s and 1840s the ship Palmyra was regularly plying between London and Demerara (as well as elsewhere) under master Croal (and this presumably can't be Alexander if he didn't get his master's certificate until 1850. I will follow up on this if you like.
Ah well, all good stuff!
Regards
David
