The chief objections to deriving "shanty" from "chanter!" are that few, if any, English seafaring terms are known to derive from French, and it is hard to understand why English-speaking sailors would adopt a French word for something they would ordinarily have called a "song" or perhaps a "stave."

The chief objections to deriving "shanty" from "chant" are that the intermediate form, "chantie" or "chanty" (pronounced with a "hard"
ch-)has never been found by the OED. And the earliest knwn example of
the sailors' word is spelled with an sh- .

You pays your money and you takes your choice.