Gibb
Aspirants. Just to clarify my point, I was not referring to any Spanish pronunciations, but to the simple point, the vast majority of seamen would have been from humble backgrounds and not known for the niceties of pronunciation. I suppose I can only speak for the vast majority of English working people who generally did not and indeed do not pronounce the aspirant unless there is a really good reason. Of course this isn't cut and dried, pronouncing the aspirant is very relative, one can do it heavily or imperceptably or not at all. It is more likely to be pronounced following a strong vowel sound, but even then it's not guaranteed. I perhaps wrongly assumed the same applied to ordinary people all over the English-speaking world.

On the other hand those noting down the shanties were by and large middle class educated people. In my opinion they would have noted it down as sung, unless they were aware that the word meant something. The later collectors can be dismissed as they would have been aware of other published collections and would imitate spellings they had seen. The earliest references are therefore the most important in giving us clues as to meaning if any.

FWIW I also think the slave origin is most likely.