To the Edge of the World also published as This Thing of Darkness by Harry Thompson (c. 2005) - ebook - Based on events between 1828 and 1865.

The first of the three books begins with the events that led to Captain FitzRoy being given the Beagle to command and chronicles his experiences as its captain during its mission in the waters of southern South America and particularly the area of Tierra Del Fuego.
Book two introduces Charles Darwin and mainly tells of FitzRoy's and Darwin's experiences in the second voyage of the Beagle to survey the coasts and waters in the southern waters. They surveyed the Falklands, the southern coasts of Patagonia and Tierra Del Fuego and also some of Chile and New Zealand and then continued around the world back to England.
Book Three gives us the rest of FitzRoy's life as well as something of Darwin and his publications. At this point the two men disagree about the meaning of their observations and are no longer friends. In the end this novel is more about FitzRoy than Darwin.

The novel is well researched and seems to closely follow the actual events. In his Author's Postscript at the end, Thompson does tell the reader where he departs from an actual event. There is also a large bibliography for further reading. I read The Voyage of the Beagle by Charles Darwin a few years ago and I didn't see any problem with Thompson's version.
Also, the novel was long-listed for the Man Booker Prize and short-listed for the Pendleton First Novel Award. At about 800 pages (print length) this took most of March to finish but it was worth it.

Hacia los confines del mundo
Harry Thompson
Publicado: 2005 | 765 páginas
Novela Aventuras Histórico

La teoría de la evolución de Charles Darwin supuso un verdadero hito en la historia del pensamiento. Al desplazar a Dios como creador único de la especie humana, el gran naturalista británico transformó radicalmente la visión que el hombre moderno tenía de sí mismo, iniciando una revolución conceptual cuyas consecuencias perviven hasta nuestros días. Y si bien el nombre de Darwin quedará inscrito para siempre en los anales de la Historia, menos conocida es la figura del escocés Robert FitzRoy, sin cuya participación la teoría de Darwin nunca hubiese visto la luz. Brillante oficial de la armada, FitzRoy es nombrado capitán del «Beagle» con tan sólo veintitrés años de edad. Aunque su misión es cartografiar las costas de Tierra del Fuego, él alberga otros proyectos igual de ambiciosos: demostrar la igualdad de los hombres de distintas razas, tesis contraria al espíritu de la época, y ratificar la teoría del origen del mundo tal como lo describe el libro del Génesis. En otoño de 1831, FitzRoy admite a bordo del «Beagle» al joven Charles Darwin, de veintiún años y aspirante a clérigo, que lo acompañará en la famosa expedición que conmocionaría el mundo. Pese a sus diferentes temperamentos, una sincera amistad unirá a los hombres, que comparten una idéntica pasión por la ciencia. Ambos persiguen denodadamente la verdad, aunque no tardan en comprobar que su concepto de verdad es radicalmente opuesto. Mientras FitzRoy defiende sus creencias religiosas y el «orden natural de las cosas», Darwin madura la teoría que lo haría famoso. Además de un vibrante relato sobre el épico viaje que impactó a la sociedad del siglo XIX, en pleno debate sobre el racismo y la difícil relación entre religión, ciencia y colonialismo, esta magnífica novela —finalista del Premio Booker— es sobre todo una crónica apasionante de la pugna entre dos intelectos excepcionales, a quienes la ciencia convirtió en adversarios irreconciliables, conduciendo a uno a la gloria y al otro a la destrucción.

La teoría de la evolución de Charles Darwin supuso un hito en la historia del pensamiento. El gran naturalista británico transformó radicalmente la visión que el hombre tenía de sí mismo, iniciando una revolución conceptual cuyas consecuencias aún perviven. Menos conocida, en cambio, es la figura del oficial de la armada Robert FitzRoy, sin cuya participación la teoría de Darwin nunca hubiese visto la luz. En 1831, FitzRoy admite a bordo del Beagle al joven Charles Darwin, que lo acompañará en la famosa expedición que conmocionaría el mundo, y cuyo objetivo era cartografiar las costas de Tierra del Fuego. Ambos persiguen la verdad, aunque no tardan en comprobar que su concepto de verdad es radicalmente opuesto. Mientras FitzRoy defiende sus creencias religiosas y el «orden natural de las cosas», Darwin madura la teoría que lo haría famoso. Además de un vibrante relato sobre el épico viaje que impactó a la sociedad del siglo xix, esta magnífica novela —finalista del Premio Booker— es sobre todo una crónica apasionante de la pugna entre dos intelectos excepcionales.

I enjoyed this so much.

I didn't expect to get beyond 100 pages, because I generally dislike historical fiction and nautical themes bore me rigid. (It came recommended, so I wanted to give it a go.)

What, I think, negated my biases were my ability to ignore the nautical stuff (sail hoisting, hoving, things abeam and all that) and because I am interested in the history of science (which is what this is, from one perspective).

However, I stayed for many things.

Central is the FitzRoy/Darwin relationship, and that's done quite brilliantly. One man unbending in his faith, one wavering while trying to play both sides, then succumbing. And yet FitzRoy is now acknowledged as the first weather forecaster; he saw patterns in "the Lord's" plan. He could see his Lord didn't micro-manage the weather, but he couldn't accept that man evolved from apes, if you will. As an atheist, it was fascinating to watch these two giants grapple with their faith/biases.

But the main story is FitzRoy's. He was a quite extraordinary man and sailor, with strong humanitarian ethics that conflicted with the British expansionist empire building of the day. He was utterly out-politiced (despite being elected as a Member of Parliament, at one point).

This is a big book (750-pages) with 38 chapters. Each chapter is a mini-story, and I found that the best way to read it – a slice at a time, rather than belting through it.

There's so much here, if you can engage with what drives the main characters during an age so different to our own, with its overt racism and sexism. ( )

A most remarkable book, and not easy to classify, if it is historical fiction rather than a lightly fictionalised biography of two remarkable men. Recounting the voyages of HMS Beagle, Harry Thompson manages to cover huge perspectives, including the technological advances that permitted the exploration and navigation of the globe by Europeans; the prejudices of Europeans against the cultures they encounter, and the catastrophic damage caused in their wake (whether by disease, genocide, exploitation or misplaced benignity - no reader will forget the story of Jemmy Button); the pillaging of the planet; and at the root of it all the fundamental debate about what a human actually is. Although they applied their individual skills and expertise in very different ways, and came to very different conclusions, both Robert Fitzroy and Charles Darwin had learnt the importance of precision and thoroughness in their data collection, their conclusions causing fundamental changes in our understanding of the planet. They were a remarkable double act, and this book shows the debt each had to the other, and we have to both. ( )