Check out Paul Clayton's album Whaling And Sailing Songs - probably out of production, but the sleevenotes give an interesting history of shanties and fo'c'sle songs. Interestingly, there are different types of shanty, eg capstan shanties, for different jobs on board. Unlike fo'c'sle songs which were generally ballads (eg Fair Spanish Ladies), shanties have a regular refrain along the lines of to-me-weigh or aweigh-boys-aweigh, on which the work was done.