1) Ballads generally do not have a chorus—essential for a chanty—or else only a short tag-like refrain ("heigh derry down" sort of thing). To use a ballad as a chanty requires appending/creating a chorus from somewhere.
2) Ballads often are narratives; the story should be completed (or the theme sufficiently expounded) before the song is considered finished. However, the work accompanied by chanties could stop/start at any time, making ballad texts not conducive.
3) Simply put, ballads—in my view—belonged to a different cultural tradition than chanties.
Still, ballad themes were part of the cultural tradition of many who sang chanties, and they were worked into chanties. This just means, however, that the ballads were layered on top; chanty forms were the base.
There were just a few chanties in the repertoire that were indeed ballads or based primarily in a ballad. This relative of "The Golden Vanitee"is one.
Harlow said it was used at the windlass in the mid 1870s. Yet Hugill is the only other writer to call it a chanty, if my notes are correct. Elsewhere it is a foc'sle song.
Here's the complete version, (A)
Version (B) is just a tune variation example:
Version (C) is just another slight melody variation, which only appeared in the unabridged edition: