"Splice the mainbrace!"

As someone who enjoys a drink, I found this answer to a query in an old Boy's Own Paper of interest and thought I'd share it.

W. A. BOOTHROYD. – To splice the mainbrace is a long job that does not require doing very often and is generally thought worthy of an extra drink – hence the phrase. In a big ship the mainbrace, where it runs through the block and is worn, is generally turned end for end, and used till another bit of it is worn before it is thought worth while to splice it.
(SATURDAY, DECEMBER 24, 1892)

Well, now I know!