What on earth made you turn to fiends to discuss this? :-)

Anyway, the McCalmans sing the same chorus on 'Festival Lights' (1995); Nick even says it at the start so people can sing along more easily. Can't tell you what exactly it means, though. For me it's simply a poetic image, referring to the hearts (men) who part the wild waves (with their ship). In that case you're right, of course, the grammar would be all wrong.