From "Peter Smalley – HMS Expedient", at Books and Writing:
Peter Smalley: … In the 18th century, each seaman was given half a pint of rum a day…in our terms (because of the strength of the rum), a pint of rum a day. So they were permanently drunk, more or less. Well, they led terribly rigorous lives, and that was the way the navy kept them happy.
Tony Barrell: And when Captain Rennie, who’s one of the main protagonists of HMS Expedient, its captain, threatens to withdraw the rum ration; that’s worse than threatening them with the lash.
Peter Smalley: I think in most ships it was regarded as the ultimate punishment because these guys were alcohol-dependent. If you took away their grog they suffered withdrawal, it was as simple as that, and they hated that more than anything. They’d rather take a dozen lashes than have their grog withdrawn. That’s absolutely true.