See my comments in the notes to 'Rounding the Horn' in the revised edition of The Penguin Book of English Folk Songs, published by EFDSS in 2003 as Classic English Folk Songs. I suggest there that 'Conway' was probably the original name ('Amphitrite' being likely introduced by the singer William Bolton); the HMS Conway, laid down in 1828, was at Valparaiso in 1835. Darwin sent letters and specimens back to England on her just prior to embarkation on The Beagle.