Steve: I haven't turned up anything new in English, as yet, if that's what you're thinking.

"Circa," ie: The entire 19th century would amount to less than 5% of the proceleusmatic document record of +2.400yrs. And by the 21st century you get: Lyr Add: Howe! Hissa! (Shanty) for the 15th century. Like finding 600 year old jazz or disco. Needs better glossary all round methinks.

French is certainly the closest I've found so far but, there are old words more specific to the maritime than the generic chanson of the wiki, Mudcat &c.