Hi Kaleea
I don't know if Anne Bonny or Mary Read moaned aaaarrrghh but as Anne's lover, Capt Calico Jack, passed them by & said "If instead of these weaklings I only had had some more women with me" she's said to have retorted "Had you fought like a man, you need not have been hanged like a dog". Anne & Mary then went on to "plead their bellies". Pregnant at that time could not be excuted.

Maybe the sound comes from seasick sailors hanging over the rail, heaving up bait & shouting at the wake.
Barry