How did people go to washrooms in coffin ships in 1815?

Answer 1

After the collapse of the Roman Empire, there were no more plumbing systems in Europe. People built little sheds over holes in the ground (Shakespeare calls this kind of privy "a jakes") Castles contained rooms built over long shafts down which the excrement fell. In towns and cities, people used little pots called chamber pots which they then emptied. Sometimes there was a special room (called in Shakespeare's day a "jordan") just like our modern loos. There were in some places septic pits or "middens" where you could dump the sewage; Shakespeare's father was given a fine for building one too close to his neighbour's house. In cities, they sometimes did not have access to a midden, so they just dumped it on the street, where the rain would (hopefully) wash it down to the nearest river (which is where you got your drinking water from).

However, they were working on improving the plumbing, at least for the rich. Queen Elizabeth had a cast-iron flush toilet, one of the earliest post-Roman examples of this technology.

Answer 2

The poorer people on the ships (those who weren't protestants) just went in the corners of the ship.