Might seem like a silly question but for the slave owners it probably doesn't make economic sense for them to be so terrible. Can I just preface this with I really don't feel comfortable about talking about people like they're a thing like this, but it's only because it makes sense in the context.
Now I'm not suggesting that slaves ships would have made sense to be luxurious, that would just be the other extreme. But as for just how bad slave ships were, doesn't make too much sense. I would have thought slave were quite valuable, so 1 you lose a lot of profit every time one of them dies, that's an enormous loss 2 it also makes sense that your product is in good condition so as to be able to get the most money for it, so you don't want to be damaging them both mentally or physically would effect the value, and 3 treating people poorly has a negative effect on productivity.
My first thought is that a lot of slave ships weren't that bad and the ones we hear about now are just some of the worst examples of human treatment so they are the ones that get talked about the most?
We've deleted several brief answers to this question. We ask that answers in this subreddit be in-depth and comprehensive, and highly suggest that comments include citations for the information. In the future, please take the time to better familiarize yourself with the rules, and be sure that your answer demonstrates these four key points:
Thank you!
More can be said on the topic of the 'Middle Passage', but we recently hosted an AMA with Dr. Sowande' Mustakeem, author of "Slavery at Sea: Terror, Sex, and Sickness in the Middle Passage" which would likely be of interest for you.
While Dr. Muskateem can talk about this with more depth and grace than I can, I want to point you towards Marcus Rediker, The Slave Ship, which pretty squarely takes on your question.
So, let's put slave ships in context. High seas shipping was a massive, profitable business in the seventeenth and eighteenth centuries, the busiest period of the slave trade. Cargoes of tobacco, sugar, timber, or wheat were numerous profitable, and had the added bonus of not trying to kill the crews tending them if given the chance. This meant that, for many crewers, work aboard a slave ship was the least desirable kind of work. The frustration born of this, plus the (legitimate) concern that the ships' human cargoes would rebel if given half a chance, prompted sailors to take advantage of the fact that they could inflict violence and death upon the enslaved more or less at will. They also used this unfettered power to rape enslaved women.
The business side of slaving also added to the human atrocities. Slave ships were often owned by companies of investors, few if any of which would ever set foot on one of their ships. Largely divorced from the human element of their business, ship owners' sole concern was maximizing profits. This meant stocking ships with as few supplies as possible and cramming in as many enslaved people as possible in the ships' fetid holds. Keeping the enslaved cargo on the brink of starvation not only cut costs, but deprived them of the energy to rebel or otherwise make trouble.
The hitch often came when ships had to wait at anchor outside of African slave ports ("factories," in the language of the day) if there weren't enough slaves to fill the ship. Getting becalmed or damaged by storms contributed to the same problem: every day not spent under sail was another day closer to running out of food and water for the voyage. If food ran low, ship masters faced a cruel, but ultimately easy truth: slaves were expendable, crews were not. While captains did not hurl slaves overboard to save on rations every voyage, it was a commonly known facet of the trade and had a robust legal framework protecting captains that did so.
All in all, the central truth of slave ships was that they existed to maximize profit for their investors without any regard for the value of human life. To the ship owners, there was no material difference between selling an extra slave or two and saving money on a hogshead of rice. Malnourished slaves could be fattened up back on land, mostly on someone else's dime if they played it right. So long as the voyage made a net profit, ship owners didn't much care about how many people died in the process.
The brutal conditions of the slave ship had another purpose. Emotionally and psychologically, the people loaded onto slave ships by the European and African captors likely still thought of themselves as free in a dire predicament. The weeks of pain, humiliation, fear, biological horror and starvation broke many, if not most, enslaved people. Rediker compares slave ships to assembly lines: free people went in one end, and came out as slaves on the other.
May I try follow-on questions? Were they generally believed at the time to be horrible? If so, was that a factor in ending the African slave trade?