The cache is not at the above coordinates.
This cache pays tribute to the excellent sea stories of Patrick O'Brian, which follow the fortunes of Jack Aubrey from his first command in 1800 to his promotion to Rear Admiral in the aftermath of the Napoleonic Wars. In the book of the cache title, Captain Aubrey and his crew, aboard HMS Surprise, chase an American frigate into far southern waters, having many adventures along the way.
Royal Navy ships A to H came later than Jack Aubrey's era, being launched in the 1920s, and for the purposes of this puzzle were cruising southern waters around the following stations:
A: S 51 30.428 E 179 55.127
B: S 52 55.821 W 179 14.396
C: S 50 48.395 W 179 56.766
D: S 52 42.705 E 177 14.728
E: S 50 03.680 E 174 48.905
F: S 54 53.568 E 177 04.057
G: S 50 21.942 E 175 51.466
H: S 51 23.625 W 179 28.262
The cache can be found at N 51 25.ABC W 000 45.(D-H)(E+G)(E+F)
