Final answer:
Manmade losses on board ships have historically ranged from those due to the deplorable conditions during the transatlantic slave trade to intentional acts for financial gain, such as insurance claims from shipwrecks, and accidents or poor choices in navigation leading to ship destruction in storms.
Step-by-step explanation:
Manmade causes of loss on board ship during ocean travel have included a variety of factors, some due to intentional actions and others as a result of negligence or unforeseen consequences. During the era of transatlantic slave trade, for instance, losses were caused by inhumane conditions that led to diseases like trachoma, which not only affected enslaved individuals and reduced the ship captain's profit but also posed a risk to the crew.
Additional factors contributing to losses include accidents, poor navigation, overloading, and intentional acts such as the infamous case of the Zong where the captain ordered enslaved people to be thrown overboard in bad weather to claim insurance money. Other examples of losses stem from environmental factors exacerbated by human actions such as storms and extreme weather events, which could lead to a ship's destruction.