Sailors sang what they pleased when they pleased. Out of earshot they could be quite crude within earshot of women children or passangers they would tend to tone it down. An old cape horner, George Herbert (RIP) that I met yrs ago sang what he said was a very crude song but that he was a "very crude fellow", so. I thought his crude songs fairly mild & that he wasn't too crude at all. But when women & children were around he'd even tone it down more than what I'd consider pretty mild. Hugill states as others do, that while within hearing range of passangers sailors would be apt not to sing cruder versions of the songs. I don't know weither or not it was a unwritten understanding among themselves or if it was known to displease the captain & his sense of rightousness in the mist of gentlemen & women who'd happen to be onboard, for some captains could out do the sailors once they've all left the shore behind.
That being said I don't know why one wouldn't just use there own judgement & if you need to field complaints, deal with it as the shit hits the fan. You may not be asked to sing again or you may be applauded for not being politcialy correct but for being right.
Barry