What follows is largely a reflection of the British Royal Navy, which was relatively unique, but also is the default archetype for what life was like in the age of sail. The world of the navy was very much a microcosm of the wider British maritime milieu in which the navy operated. This meant that although there was a very strict social hierarchy, there was a minimum level of sea knowledge all men were expected to possess. The regular seamen (ratings) came from the fishing villages, coal fleets, and merchant marine. Most of the ratings tended to be volunteers in peacetime. In times of personnel shortages, the Navy resorted to the impressment to gain its ratings. The popular memory of a press gang impressing by force an innocent landlubber is a narrative construction of the Victorian era. While some press gangs worked ashore, the Navy preferred to do impressement at sea. This was so it could evaluate the sailing skills of its new "recruits." Despite the reputation of the Navy, volunteers for the service were relatively common, even in war. Although the Navy had a reputation for paying its sailors late, if at all, its standards for food and medical care was far higher than in the civilian sector. The Navy also employed a larger number of "idlers," sailors who did little work. Especially as manpower shortages became acute during wartime, civilian ships tried to man with the least number of sailors as possible, increasing the workload. The necessity of having men to man the guns and excess rig of the man o' war meant the average workload was less than a civilian ship.

The sea officers were a social class onto themselves. The officers are grouped into two basic divisions: warrant and commissioned. The warrant officers tended to be the skilled craftsmen and technical officers, such as gunnery officers carpenters. Commissioned officers often began their careers at sea as young midshipmen (a type of petty officer-see below). Their families often had a personal connection with established officers and the midshipmen position was something of an apprentice. The men were often second sons of the nobility or gentry or the family had some kind of maritime connection. The most important rite of passage for commissioned officers was the lieutenants' exam, in which he would sit before a panel of experienced sea officers and pass an oral exam on navigation, seamanship, and other nautical issues. If he gained his lieutenancy, his career was open to greater advancement. In theory, if a lieutenant could stick out the poor pay, keep his nose clean and stay in the service, he would become an admiral as the Navy based promotion upon seniority (in practice, advancement to flag rank was much harder, but seniority mattered a great deal).

Between the commissioned and warrant officers were a large amorphous bunch of ranks known collectively as petty officers or inferior officers. Some of these men were the assistants to the warrant officers, such as gunsmiths or sail-makers. Midshipmen were frequently young gentlemen who were thought to eventually rise to lieutenancy.

The issue of discipline, like the press gang, has been subject to a lot of mythology. Corporal punishment was the norm, but officers tried to maintain a balance between harshness and leniency. In practice, Royal Navy ships were compartmentalized by divisions headed by an officer. these officers were responsible for maintaining a level of discipline within these small units. The best run ships had a self-regulating body of men that kept the punishment for most infractions in house. It was a dangerous thing for the ship to be divided between the senior officers and the ratings, most famously demonstrated by the Bounty. Captain Bligh was a skilled sailor and accomplished officer, but his method of berating the crew (his "bad language") and reluctance to impose corporal punishment created a situation whereby the crew saw him as the sole face of authority.

The multi-tiered warships like HMS Victory were relatively rare within the Royal Navy. The typical warship was quite small and cramped. Some of the ratings preferred the smaller ships despite the difficulties inherent in life aboard such vessels. There was a closer camaraderie in the smaller ships and there was a greater opportunity in wartime for prize money.

Although I love the film greatly, the biggest problem I have with Master and Commander is that it changed the nationality of the novel's antagonists. The Acheron was originally the USS Norfolk and Aubrey was defending the crown during the War of 1812. It's yet another example of 1812 being a forgotten war.

Aside from Patrick O'Brien's novels (and I love the film), check out the writings of N. A. M. Rodger for more detailed answers. He's a highly accessible naval historian and renders the complex world of the Navy far more intelligibly than I did here.

Sources

Rodger, N. A. M. The Wooden World: An Anatomy of the Georgian Navy. Annapolis, Md: Naval Institute Press, 1986.

-. The Command of the Ocean: A Naval History of Britain, 1649-1815. New York: W.W. Norton, 2005.