Could you live indefinitely on a boat?

I have a novel rolling around in my head, and I’m trusting you guys for my research. When I accept my Nobel prize in the field of literature, I’ll make sure to mention you.

Now, seriously. Imagine a population of a few hundred people on board a really big mother of a boat. Think Queen Elizabeth. Think navy aircraft carrier. That kind of boat. Let’s say we have a bunch of cash and convert it into a big floating farm, growing crops. We also have some really big fishing rods. Could we sustain this population (let’s say 300 people) indefinitely on the boat? How much artificial farmland would we need?

I suspect the big problem will be acquiring enough freshwater. How do those nuclear submarines that can stay at sea for months do it? They can’t bring that much water with them, can they? Is it realistically possible to desalinate sea water for this purpose? Could we recycle it?

If not 300, how many do you think we could manage to sustain? The boat has no other purpose other than keeping these people alive and in a reasonably good mood.

I’m pretty sure you can’t grow enough food on a ship of any size to support 300 people for any length of time, although I wouldn’t venture to guess how many you could work in…

Submarines are reprovisioned by supply ships fairly regularly; I’m not quite sure how they did so while floating around in Soviet waters though.

Nuclear powered boats desalinate seawater.

Nuclear subs crack sea-water to generate oxygen for breathing.

If the folks on board don’t mind eating a LOT of fish, with the occassional seabird, it might be doable. You can grow food on the decks, and if nuclear powered you could use lights to grow food on indoor decks.

You’ll need a really good recycling program for the food waste and human waste

But, over an extended period of time you’ll have to deal with erosion of the “farmland”. You’ll have to be resupplied with things like metal and pharmaceuticals somehow, which you can’t ger or reasonably be expected to make while at sea. Or learn to do without.

In theory, yes - in practice, not very likely.

Are you going to raise your crops in the traditional way, or hydroponically?

In any case, you’re going to need to protect them from salt spray and wind burn, while ensuring that they get adequate light to grow properly.

Water wouldn’t be a problem if you have a nuclear power plant onboard - you’d just purify it from seawater.

Nutrients for the plants wouldn’t be a problem - fertiliser can be manufactured from effluent and surplus/scrap seafood.

Your main areas of concern are (I believe):
Space (how much crop-growing space is required to support 300 people?)
Pests and diseases - in a relatively isolated and fairly self-contained environment, you might get the pest, but not its main predator - crop failure would be a disaster if you are working at full capacity (or nearly so).
Maintenance - what happens if your desalination plant breaks down.
Size of the gene pool - if you’re saving your own seeds for next season’s crops, do you have a diverese enough gene pool to maintain a healthy lineage.

Oh, and also:

Durables - what will you do when your shoes wear out, or when someone drops their gardening trowel overboard?

Consumables - soap, toilet paper, light bulbs, etc, are you going to make these onboard?

If you really mean indefinitely, you need a way to obtain raw materials and a basic industrial capability to manufacture all the necessary equipment yourself. I think organic material (“top soil” or fertilizer) can be replenished from the sea. Obtaining metal (or metal ore) might be difficult though, I don’t think we have the technology to mine the ocean floor for anything other than oil.

I wonder how hard it is to maintain a watertight hull without ever going into a dry dock? Maybe you want a kind of raft made up of dozens of small boats rather than one huge ship. You probably need a dry dock to service the boats or build new ones.

I think you need much more than 300 people to maintain a self-contained civilization like that. A few thousand at least.

Any way that puts food on the table.

So nuclear submarines desalinate sea water. Cool. The water problem’s sorted.

As for food/human waste, couldn’t we compost it and use it for fertiliser?

My main concern. I cannot find a reliable source about this. The closest thing I got said that a human needs 30 hectares to live using cut-and-burn farming, which the article regarded as an inferior method. It helpfully failed to mention how many hectares are needed using a superior method. I also found a lot of stuff saying how if everyone ate like an American we’d need three Earths. Doesn’t exactly help.

Hadn’t thought of this. Making a mental note.

That would suck. I’ll have to bring lots of spare parts and some ace technicians and mechanics.

Couldn’t I do something like this? Isn’t that doable with crops?


As much as possible, but it is a problem.

Maybe we should think bigger, like scr4 suggests. Imagine an entire fleet of ships. The population is up to several thousand. We have one farm ship, one factory ship, one residence ship, and so on. I’m beginning to think that only one ship will be impossible to pull off without a Captain Nemo-style island to return to every now and again, and if we have an island we might as well live there.

Have I mentioned that I really, really love this place? Where else could I ask something idiotic like this and have serious, well thought out answers within the hour?

It’s practically certain you’d need to trade with people on land. A nuclear powered vessel would require uranium, which has to be mined and refined; a conventionally-powered vessel would need fuel, and I assume you’re not going to rely on whale oil. Wind/wave power might work, but you’re at the risk of calm weather if you use it for general electrical services as well as movement.

Harvesting the sea for weed and fish should provide most of your food - many seaweeds are rich in nutrients, and fish is a good source of protein and vitamins. But this would require a major change in eating habits. I don’t know if there would be a way to get refined sugar or many spices, but you wouldn’t run out of table salt.

But human beings have relied on trade for hundreds (if not thousands) of years: even in the middle ages things like spice were imported, and in the past few hundred years, metals, textiles/furs/hides and many more foodstuffs.

There are many ways the boat could be economically self-sufficient, from running offshore banking and web-hosting (via satellite?), or tourism, to extracting rare metals from seawater, commercial fishing, and harvesting other ocean resources.

We’d need a good cook, but the less crops we need to grow, the better.

Maybe we’ll have to settle for economical self-sufficiency. I’m a bit skeptical about the rare metals from sea water, though. Is there really enough of that to make that practice viable?

Do they have to be entirely self-sufficient? Can they meet and trade with fishing boats?

Well, I’d rather have them make it on their own. That appears to be impossible, though, so I guess I’ll have to settle for them breaking financially even.

That’s way too easy. Almost all commercial ships fit that definition - they have enough living space for the crew, and earn enough money to pay for the necessary supplies and maintenance.

Too easy? Well, total self-sufficiency appears to be too difficult.

OK, question: could you in theory mine metal from the ocean floor? We might not have the technology now, but that doesn’t mean I can’t write it. If only we get the metal deal licked, it looks like we’re on our way.

Certainly. I can’t see how you’d do it without land-based machinery though; you’d need oxygen tanks unless you had an unmanned submersible or something similar though.

Why not a manned submersible? We’ll build oxygen tanks; what’s so difficult about that?

You have to have some method of distilling the oxygen…

AFAIK that requires a rather large tower; I don’t think you could fit one on a boat. Also, building pressurized oxygen canisters requires some serious kit, although I guess you could just stock up with them beforehand…

Well you wouldn’t need to grow food - sea plants and fish would provide more than enough of that.

You could make up some sort of mining device to get the metal ores. Maybe they know what areas of the sea bed have various ores underneath in a similar way that geologists can tell a lot about whats under the surface from the surface. So they drop some sort of automated mining device, sail away, and come back in a few months once its got lots of ore. They could have a few of these things scattered around, mining different types of ore.

They could use solar power if they’re mainly sticking to tropical latitudes.

They would definately need oil though, mainly to make plastics, and other materials like rubber. An off shore oil rig would solve that problem, but i’m not sure if you’d allow that?

Freedom Ship. Probably not quite what you’d be looking for, but it might be useful in terms of figuring out some of your storyline.

Well, according to Broomstick nuclear submarines crack sea water for oxygen, so we could do that. On the other hand, why not use air? Am I being horribly ignorant about submarines here?

I’d prefer to do without, but you can’t have everything. But do we really need oil? Plastics weren’t invented too long ago, so we should be able to regress to a non-plastic-using civilization. Is rubber absolutely necessary?

I’m pretty sure you could extract it from seaweed, but if you’re growing stuff on board, then you could grow sugar beet.