Funny experience just now in Chrome - typing not appearing in the box here!

Anyway, I think the above is a pile of poo. Shanties (originally work songs as distinct from forebitters) are examples of folk songs. Folk songs are defined by derivation not style. The only wrong you can do a folk song is not to sing it (I think Martin Carthy said that). Folk songs are not set in aspic.

How to sing a shanty is a matter of taste. If you want to change the timing so it is too irregular (or slow or fast) to be used as a work song, do it. If you want such or such a harmony, sing it or arrange it. If you want instruments on it, do it.

Personally I hate pianos on folk songs (one and one only June Tabor song excepted) and I often hate banjos (I heard one played sensitively last week, and on another occasion a different one two years ago) and indeed ukuleles. Shaky eggs can be OK or can be bad, and the same goes for bodhrans and cajons and triangles are usually horrid but can fit in some cajun stuff (which I don't like anyway) - but these are matters of taste, not the nature of the song.