Some cats may be interested in relatively early U.S. evidence that shanties were not part of U.S. naval practice.

From "Songs of the Sea - What and How the Sailors Sing — Merchantmen's 'Shanties'," San Francisco "Daily Bulletin," Supplement, Nov. 17, 1883, p. 1:

"'The men don't sing much except when on a long voyage; but when they rerally get settled down for a trip, then you will hear them at it,' said a naval officer recently to a Tribune reporter....

"'"Shanty" songs are working songs, and are sung in the merchant service.'"