I'm trying to figure out what a huge swimming ark that is able to support maybe 10.000 people would look like. It's for a P&P campaign. And please excuse any bad grammar, spelling or poor word choice, I'm not a native English speaker.
- The world is covered basically entirely in water (think Waterworld, the movie). I assume that also means that there are more rainfalls than in our world.
- Magic doesn't exist.
- The ark was being built with technology that was available during the industrial revolution, but I'm flexible about this. Science could have advanced in a different order in this civilization but they definitely didn't have lasers e.g.
- The ark has been on its journey for a very long time now, let's say 300 years and has had no contact with any outsiders. That means that it has to be entirely self-sufficient. It also means, that society and culture have deviated quite a lot since it left. Most people have no idea what their ancestors life was like before they left their home, or when and why they did it in the first place. Many machines broke during the time and there was no one to repair them because they didn't have the replacement parts or they forgot how it works.
- And finally, the lower decks are 'lost'. They are off limits to the general public and swarmed with monsters. They are basically dungeons where adventurers can go and try to find valuable equipment or books or whatever.
But what would such an ark look like? It doesn't need to berth or navigate very well and it is much larger than anything ever build in real life, so it could have quite the different shape than conventional ships. E.g. how high would it be and where is the waterline?
- Sunlight is one. Maybe they would try to build a lot of relatively thin towers to maximize surface and get more sunlight. But then, why don't you see that in real ships? (I don't actually know anything about ship design though, hehe.) Living space on the top deck would definitely very coveted, reserved for the government and rich merchants and the like. Which brings me to the next point.
- Space. The ark would probably be tightly packed. People would be living in tiny apartments like in Tokyo City. Poor families would live in the lower decks, the rich would display their status by living on the top floor. Towers would emerge automatically from this system, unless prohibited. But would they own it or rent it? I think it would make sense for the government to own the entire ark and collect rent, but there may be some exceptions. Also it may be difficult to collect rent in some of the lower decks where crime lords could be the actual rulers.
- Fresh water. Unless there is a good way to remove the salt from seawater, they would have to collect rainwater. So I think they would build big awnings collecting the water and reservoirs to store it in. But the awnings would block the sunlight so they would only be put out during rainfall.
- Air. The air in the lower decks would probably be pretty thick. Careful ventilation shaft would be constructed to ensure an optimal circulation. Maybe they could have something like the $CO_2$ scrubbers they have in spaceships?
- Food. I'm having a hard time imagining how they would provide enough food for everyone. In medieval time, most of the land was just farms producing food but in this case this is just not possible. So if they use agriculture they would need a plant that has a ridiculously fast agricultural cycle. (And possibly a plant that doesn't require a lot of sunlight so you can grow it beneath the surface.) Maybe they could have small floating islands dragging behind them to grow their food. But these island would be vulnerable to storms and high waves. So maybe plants that can grow in saltwater like mangroves that also bear fruit? And maybe it is possible to grow some plants on the hull underwater and there are occupations like pears divers who harvest them. Also, obviously they would fish a whole lot.
- Power. You would probably want some mechanical part in the ship that require power (like pumps). You can't burn fuel because it would run out so maybe they have a lot of wind turbines?
- Waste. Ok, that is kinda the opposite of a rare resource but it has to go somewhere. Organised plumbing is necessary. Even in the lower decks disposing your waste improperly would probably a serious offense. They would probably use it to manure their plants.
Recycling would be a big deal in general. You can't get anymore metal than what you started with, if something gets thrown overboard and it doesn't float, it's probably gone for good. Getting new wood is not a problem in principle, plants get their carbon from the air, not from the soil.
- Fire, definitely. I'm not sure how the ship survived for so long without a major fire breaking out. What would fire prevention and fire fighting techniques look like?
- Leaks. I'm laughing at the idea of some ignorant fools trying to build a well. I guess the hull is just build very sturdy, and that's that.
I'm also wondering what sort of social structure would emerge from this. In the beginning there would most definitely a powerful government. Both because it's necessary to guarantee the survival of the colony and also because only a strong government would have been able to build the ark in the first place. But over time it could have lost a lot of influence. This is, in a way, required since the fact that the lower decks have become dungeons is a non-negotiable feature of the setting. I'm also having trouble imagining what the typical job would be that you can have in this world. And I probably overlooked a lot of details that would change from the '3D-ness' of the whole city. There wouldn't be just streets there would be a lot of staircases, pulleys, chutes, (possibly) elevators and the like to make transportation between floors easier, kind of like a modern shopping mall. By the way, I think inside the ship you wouldn't really notice that you are on a ship, it would be too large to sway noticeably.
These are my thoughts so far at this moment. How feasible is this setup? What did I miss?