Via Ouija board, perhaps?
Not to mention cologne. 
Are you…criticizing Patrick O’Brian? Best prepare yourself for 3 well aimed broadsides in 5 minutes.
Other than the fact that he’s been dead for 17 years?
Well, if you think you can do better…
Give a man a preserved fish, he’ll eat for a day. Teach a man that someone was once named Preserved Fish, he’ll laugh for a day.
Sell a man a fish, you feed him for a day.
Teach a man to fish, you lose a steady customer.
Here’s part of the coffee-making process at sea during the same period as explained by C.S. Forester in Hornblower and the Hotspur. However looking at it closely I see it’s all about grinding the beans and not much about the brewing; straining it is mentioned.
Hornblower explained about coffee to Grimes while working up a lather with a quarter of a pint of fresh-water.
“Count out twenty of those beans. Put them in an open jar—get that from the cook. Then you toast ‘em over the galley fire. And be careful with ‘em. Keep shaking ‘em. They’ve got to be brown, not black. Toasted, not burnt. Understand?”
“Well, yes, sir.”
“Then you take ‘em to the surgeon, with my compliments.”
“The surgeon? Yes, sir.” Grimes, seeing Hornblower’s brows come together like thunderclouds, had the sense to suppress in the nick of time his astonishment at the entry of the surgeon’s name into this conversation.
“He has a pestle and mortar to pound his jalap with. You pound those beans in that mortar. You break ‘em up small. Small, mark you, but you don’t make dust of ‘em. Like large grain gunpowder, not mealed gunpowder. Understand?”
“Yes, sir. I suppose so, sir.”
“Next you—oh go and get that done and then report to me again.”
Grimes was clearly not a man to do things quickly. Hornblower had shaved and dressed and was pacing the quarterdeck, raging for his breakfast, before Grimes appeared again with a panful of dubious powder. Hornblower gave him brief instructions on how to make coffee with it . . .
“Coffee, sir?” said Grimes. . . He poured from a jug into a cup, and Hornblower sipped. It was only just hot enough to drink, which meant that it was not hot enough, and it was muddy.
“See that it’s hotter than this another time,” said Hornblower. “And you’ll have to strain it better than this.”
That leads to one of the humanizing incidents of Hornblower.
WWJD?*
*What would Jack do?
I find it odd so many British heroes prefer coffee to tea.
Perhaps it is authors who prefer coffee.
Well, Hornblower and Aubrey are both based in part on the same real-life man. I don’t know whether Cochrane himself preferred coffee to tea, but he wrote plenty, and Forester and O’Brian would have read it all. That would make the connection in a single step.
Coffee also is a nice literary device, as it provides an element of distinction/personality for the character.
Here’s an article describing how in the late 1600s-early 1700s “London became a city of coffee addicts. By the dawn of the eighteenth century, contemporaries counted over 3,000 coffeehouses in London although 21st-century historians place the figure closer to 550.”
And another article about the London coffeehouse of the 1700s as “a haven for caffeine-fueled debate and innovation which helped to shape the modern world.”
According to this article, coffee was viewed as a man’s drink while women drank tea:
https://www.janeausten.co.uk/what-would-jane-drink-coffee-in-jane-austens-work-and-world/
As for coffee and distinction, when Jack and Stephen are on the Lively they’re not happy that it’s a cocoa-drinking ship and coffee is not served.