ALL HANDS ON NECK!
Navigate the fretboard and sail the high ‘C’s with four swashbuckling scale shapes...
These are the most common (though certainly not all) scales you’ll need. The typical singing range of the shanty is factored in, though you could certainly go deeper and play in G, F or E. Choruses and final ‘responses’ typically end on root notes, while ‘calls’ tend to land on naturally ‘questioning’ scale degrees (usually the 5th, but sometimes the 2nd or other degrees).