An un-treatable virus starts infecting and killing people. Societies are on the brink of collapse, and it is decided the best way to save the most amount of people is to move everyone who can fit into nuclear-powered aircraft carriers and then out into the pacific ocean.

The basic plan is to have all the nuclear-powered aircraft carriers, and boats bringing people from shore operate alone for a month, so any infected that slip through the screenings have time to expose itself. A small government craft will approach every boat (never touching or docking) for a census count and ration delivery twice a week. After that, all the nuclear-powered aircraft carriers will link up to form a large artificial island.

Every landmass has the infection, so docking anywhere after setting out, is out of the question. Governments set the sail date two weeks away, hopefully enough time to get non-infected people and boats into quarantine zones. All nuclear-powered aircraft carriers are going to be part of the island. Large tanker ships trade their oil for freshwater, and the nuclear-powered aircraft carriers cover their massive square footage with soil to produce a small harvest to supplement whatever can be fished. What ever rations are available are gathered, and the rations are shared for the first month of isolation, but the bulk of this food is saved for the world leaders and ruling class.

So I am wondering, could this human civilization live 150 years in a nuclear-powered aircraft carriers colony? The best answer would answer in two parts, the first being how many people could be part of the colony, and would there be viable food for that sized group after the first month? If the civilization wanted to survive 150 years, would they have to have a culling and resort to cannibalism?

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    $\begingroup$ If touching land anywhere is forbidden, how do they get food? $\endgroup$
    – L.Dutch
    Commented Jun 24, 2019 at 15:02
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    $\begingroup$ Surely by "boats" you mean nuclear-powered aircraft carriers? A regular ship cannot endure for one year at sea, much less one hundred and fifty: it needs fuel, if nothing else. And most ships are not designed to be fueled at sea, while most tankers are not designed to refuel ships at sea. An unpowered ship will be sunk by the first storm. Moreover, just about all extant ships are made of steel and are won't last a decade at sea without regular maintenance. Sea water is corrosive. $\endgroup$
    – AlexP
    Commented Jun 24, 2019 at 15:14
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    $\begingroup$ There are plenty desert coasts in this world, utterly devoid of human inhabitants or at least with neglijible human populations. Why wouldn't the powers that be establish a colony on the Skeleton Coast, for example, to provide the facilities for ship maintenance? It's not as if there is a dense human population there to enable the virus to survive. $\endgroup$
    – AlexP
    Commented Jun 24, 2019 at 15:26
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    $\begingroup$ Seems like C.M. Kornbluth covered much of this territory in his short story Shark Ship (1958), including the dangers of landing. $\endgroup$
    – user535733
    Commented Jun 24, 2019 at 15:57
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    $\begingroup$ Oil tankers cannot be converted to carry fresh water. Crude oil is extremely toxic, and some of it sticks to the inside of the tank and pipes. Washing out the tanks and flushing the pipes sufficiently that they wouldn't poison the water would be far more effort than other conventional solutions. Many ships have machines that make fresh water out of sea water. As far as I know, that includes aircraft carriers. If you want to quadruple the number of people on the carrier, you just need to install three more freshwater machines to meet the demand. $\endgroup$
    – Jared K
    Commented Jun 25, 2019 at 16:06

11 Answers 11


You have problems, and it isn't food

Food is easy. The ocean is full of fish. So long as your story places the aircraft carriers in the right place, food is irrelevant.

Your problem is nuclear fuel. Those aircraft carriers are big, sealed, bathtubs. Without ventilation, the CO2 resulting just from human breathing would slowly make the lower decks uninhabitable (IMO). The ventilation is designed for electricity, so electricity is the tall pole in your tent.

And electricity on a nuclear-powered aircraft carrier depends on fuel rods. The period between refueling for a Nimitz-class aircraft carrier is 25 years.. Could that be stretched? Somewhat, but it's not like you can parcel fuel rods out over time. So, 150 years is completely unbelievable without replacement fuel rods, and disposal of the old ones (don't want to radiate the fish!).

If you let the ventilation die out, then you're restricted to living on decks with access to port holes, doors, etc. that open to the outside air, and maybe (maybe) a deck below that. I honestly don't know how far toward the keel portholes go, but you certainly won't have them below the water line. And considering the nature of storms over the ocean, it's unlikely people will want to live on-deck.

Just out of curiosity

  • You have a deadly disease that's killing people. Why do you have to wait 150 years? If it's that lethal, you'd only need to wait 5-10 years before 90% of the population was killed off and huge swaths of land became re-inhabitable. 150 years is an awfully long time. One would hope your doctors aboard the aircraft carriers were trying to eradicate the disease and that medical equipment to do so would be among the highest priorities during those early shipments from land. I find that 150 number really hard to choke down.

  • This plot is hauntingly similar to The Last Ship by William Brinkley. You might want to go read that novel. Your aircraft carriers would be in radio contact with everyone they possibly could for the entire 150 years, tracking the viability of returning to shore anywhere.

Edit: User "user" pointed out in comments that there are off-shore solar arrays, wind turbines, and even oil platforms (indeed, any pre-existing the apocalypse energy-producing platform* is usable to partially or completely offset the lack of new fuel rods. Well done, user!

Also, noting Forbin's actual experience as a Navy nuclear operator (it's absolutely amazing who uses this site!), refueling at sea is, fundamentally, impossible — making all discussions about disposing of the rods irrelevant (go read that comment. Holy schmoly it's a process).

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    $\begingroup$ "and disposal of the old ones (don't want to radiate the fish!)" -- water is an alarmingly good nuclear shield, I would have thought they could drop it to the bottom of the ocean without much of an effect on the ocean life there (see: what-if.xkcd.com/29 and web.archive.org/web/20130329134345/http://www.isoe-network.net/… ) $\endgroup$
    – Aster
    Commented Jun 25, 2019 at 20:11
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    $\begingroup$ I am a former Navy nuclear operator. Refuelling a nuclear ship at anything other than a shipyard refuelling facility is out of the question. You have to cut the ship open and remove the core and its surrounding pressure vessel and replace the entire thing. This only happens with a large, heavily manned industrial facility. And for a large nuclear surface ship, you're not going to be able to supplement ship's power from these other sources without being tied up alongside the facility, with ship-compatible shore power connections. Finding such - not in a port - is highly implausible. $\endgroup$
    – Forbin
    Commented Jun 25, 2019 at 23:45
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    $\begingroup$ I cannot think of an example of a disease that is 100% fatal. Always some survivors. $\endgroup$ Commented Jun 26, 2019 at 2:45
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    $\begingroup$ @SherwoodBotsford, Prion diseases are usually rapidly progressive and always fatal. Fortunately, they're rare and have long incubation periods, meaning they're not very communicable. Heaven help humanity if anyone ever weaponizes one. Also, why not use at least previously uninhabited islands is a perfectly good question - but it's also a Frame Challenge. $\endgroup$
    – JBH
    Commented Jun 26, 2019 at 4:30
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    $\begingroup$ @SherwoodBotsford Have you ever heard of Rabies? That is 100% fatal. There have been a handful of medical miracles involving the "Milwaukee protocol", which reduces that down to an estimated 92% fatal. $\endgroup$
    – Aron
    Commented Jun 26, 2019 at 5:26

There's a lot that goes into answering this, and the answer could turn into either yes or no depending on what assumptions and trade-offs you make.

Firstly, nuclear carriers have an operational lifetime of 50 years, and get a overhaul and refueling at the 25 year mark. This is assuming that the carrier is actively being used for military purposes, if you're content to let it float or cruise at low speed in the middle of the ocean, this timeline can likely be extended to a degree, however there will come a time when the nuclear plant has to be shut down because the lack of maintenance makes it too dangerous to operate even if you've still got fission fuel.

Second bit, there's a lot of stuff happening on an CVN that's just there to keep it in fighting shape: F-16s? Chuck 'em. Avgas? No need for that. Munitions? Garbage. Steam machinery, catapult piping, arrestors, carrier ops, all gone. Machine shops? Cut those back and re-purpose them to ship maintenance. That will free up a lot of space and mass.

Third bit, food and water. Assuming that whatever plague can't be transmitted through consuming fish, the bulk of the ark's diet will be based on fish, seaweed, maybe using algae as a supplement, and hydroponically or aeroponically grown citrus. A meat based diet like those of the Inuit actually provides all the nutrients and vitamins you need as long as the whole animal is consumed - but fruits and vegetable carry vitamin C in much larger quantities and are thus the best source for it. That means you can afford to feed a much larger population than you'd expect if you're assuming that you're growing everything on board.

Fourthly, corrosion and fouling. As others have mentioned, seawater is beastly stuff. But, there are ways around it. Sacrificial anodes have been mentioned, and it's simple enough to just stock up on a whole bunch of those. Wrap them up in airtight bags and attach them to floats then toss them overboard on a line if you've run out of space on board. Fouling wise, you CAN remove it while still at sea, it's just more of a hassle than it's worth, which is why it's usually done in dock. But there's nothing stopping you from coming to a dead stop and sending out a bunch of divers with electric scrubbers to scrape off fouling. You can take it a step further if you have the equipment, and you can always set it a few years in the future and say they've got ultrasonic anti-fouling hull vibration systems or electrified graphene coatings.

Fifthly, weather. No great way around this. You'd want to keep north, where the water is too cool for hurricanes to form. Not south, because the waves there get really high. Still, you'd need some power to station-keep. By the time your nuclear reactors spool down, the carriers should have working kite sails to be able to maintain some maneuver capability. Their size works for and against them: they're big and thus stable in high seas, but they're also difficult t move with wind alone.

Finally, is this infection magically bound to all pieces of land? There are a lot of uninhabited islands out there that would be a lot more viable for long term habitation than living on the ocean all the time.

  • $\begingroup$ Not magically but yes bound to land. $\endgroup$
    – Alex
    Commented Jun 27, 2019 at 14:04
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    $\begingroup$ An aircraft carrier requires an unbelievable amount of non-food comsumables. LIght bulbs, notepads, sanitary supplies, toilet paper, filters, non-fuel lubricants, fanbelts for air handlers and other machines, electronic spares (whole assemblies, circuit boards, bit piece components), machinery spares, clothes, spare anodes for the water heaters, heck, spare water heaters... The list is immense. Also, you'll need enough qualified divers to last that 150 years. Carriers have very large water intakes along the hull to provide water for the evaps and cooling. $\endgroup$
    – user66060
    Commented Jun 27, 2019 at 16:54
  • $\begingroup$ You're right of course, there would have to be both a lot of adapting the carrier to use different systems to fulfill some of those functions, as well as the development of an onboard industry to make the rest. Likely there would be periodic trips to land by people wearing hazmat suits in order to scavenge the ruins of the old world. $\endgroup$
    – Algebraist
    Commented Jun 28, 2019 at 3:42

Assuming dirt farming, as opposed to large scale industrial hydroponics, aeroponics, or mycoculture it takes roughly an acre of land to feed a human for a year. We can reduce that somewhat if we assume that the fleet harvests plankton, krill and other high density marine life. Further still if the fleet can take advantage of some of the more advanced techniques available to the modern close space farmer but you're still looking at relatively large volumes of space for farming per person.

I think the fleet is done for; let's look at an example: The flight deck of the Abraham Lincoln is roughly 6 acres and it ships nearly 5700 crew and flight wing.

The bigger problem is that none of the ships will be afloat after more than a couple of decades at most, seawater is one of the most corrosive substances known to man, without regular changes of their sacrificial anodes ships hulls will simply fall apart. Without anti-fouling measures, that require dry dock time to complete or renew shear weight of marine life will sink ships.

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    $\begingroup$ I don't think fouling would sink a ship. Oilrigs and marina pontoons float for decades without doing anything about it. All it causes is drag when you're moving. I suspect our ships would farm it. $\endgroup$ Commented Jun 25, 2019 at 9:15
  • $\begingroup$ Hey! If everyone poops on the deck, they can farm potatoes! (obvious reference) $\endgroup$ Commented Jun 25, 2019 at 12:37
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    $\begingroup$ @RobinBennett Okay I was under the impression that rigs had pretty rigorous maintenance schedules that include defouling, especially the free floating ones. $\endgroup$
    – Ash
    Commented Jun 25, 2019 at 14:43
  • $\begingroup$ @Ash If they do, then it should be possible to do for a ship too - just more difficult / costly. $\endgroup$
    – IronEagle
    Commented Jun 25, 2019 at 22:31
  • $\begingroup$ @RobinBennett Ash mentioned Sacrificial Anodes being regularly bolted to the hull. $\endgroup$
    – Aron
    Commented Jun 26, 2019 at 5:31

Your generation ships will have 99 problems. Food and fuel won't be two of them.

Food won't be a problem if you like fish.

Fuel is a bit trickier, and requires command staff to know at the outset that their nuclear carrier is now a generation ship. Let's pause to look at the nuclear ship refueling cycle.

The refueling cycle

When a reactor shuts down, nuclear fuel keeps making heat. Civil reactors handle their fuel "wet". CanDU and RBMK have removable plugs that allow machines to swap fuel rods while the reactor is underway, and it's kept wet in the machine. BWR/PWR/VVER types, you have to shut down and pop the lid off, and the spaces above the reactor lid are a huge pool that you flood. (e.g. the worrisome fuel pool in Fukushima reactor 4). That's how you manage decay heat.

With military reactors, there's no space for that. So you must wait a long time for the fuel to cool enough to even start your refueling operation, so you use that time to do a systems overhaul as well. This whole deal takes 3 years.

So. Suppose your ship is on year 25 and the drydock is ready. But wait! War is imminent in the next 1-3 year; you'd be caught in drydock. That won't do. So your refueling/overhaul is deferred. In year 27 war begins, you see robust action through year 32, but no overhaul yet: another boat needs it more due to battle damage. So year 35.

Also, suppose on year 35 they have been idling for 12 hours and suddenly they gotta go Right Now. That reactor will in a Xenon Pit. So it'll be built with the control-rod "authority" to quickly blow through it and regain full power, without resorting to safety violations like Chornobyl. We're talking a lot of reactivity and rod authority that will keep it going when it doesn't have a xenon pit.

Military reactors are sized for contingencies.

Getting to 150 years

Nuclear fuel is pretty simple: fuel burnup is proportional to the heat energy you use. Carrier reactors are sized for a career of high tempo maneuvering: lots of fast cruise and generous use of energy since it's plentiful.

If you can reduce power consumption, your reactor lasts longer in proportion. Making it to 150 years takes about an 80% cut in energy usage. Obviously you will be quitting flight ops, and minimizing sea cruise. Keeping propulsion at tickover, just enough to maintain sea stability, or weighing anchor somewhere, will be key. Then you cut down your electrical loads and reduce your heating loads with good insulation (which you didn't really need before).

I would expect that most of the time, one of the two reactors would be shut down. The ship is more than capable of fighting on one reactor, so it should be able to serve in "generation ship" mode with one reactor at low power.

The experience of the civil nuclear industry is that reactors age quite well. There haven't been an appreciable number of new US plants since the 1980s, so they're all quite old - and yet they are repeatedly recertified, even in a post Chornobyl post Fukushima age. The only major difference is that carrier reactors use salt water as an ultimate heat sink in heat exchangers, and corrosive salt water may be an issue.

One option to slow or arrest salt water corrosion is for the carrier group to relocate to a river which allows them to sail sufficiently upstream to be in fresh water. As discussed, this would be one of their 99 other problems.

One way to deal with hull maintenance is to use bulldozers, tides and pumps to make a man-made basin, and an improvised "lock" made by pushing dirt around. Float the carrier into the "lock", fill the lock and basin, float the carrier into the basin, then open the "locks" and let the carrier settle onto the earth - the equivalent of blocks in a drydock. Then, to reach the carrier bottom, you tunnel the dirt out from under the carrier, in narrow strips of maybe 20 feet wide, so 90% of the carrier bottom is still supported by earth. You remove barnacles and replace the bottom antifouling, and when it cures, refill that tunnel and dig another tunnel. You could do this in a continuous "bubble", digging out on the aft side of the tunnel and repacking the dirt in the forward side. When the process is done, have the bulldozers re-create the "lock", pump the basin full of water, and float the carrier back to sea.



As others have mentioned, food isn't an issue. You have fish and you have seaweed. You can farm fish and also do things like grow oysters on strings. Some vertical farms on the boats could grow some land vegetables (with compost adding to the soil so it doesn't deplete). Fermenting the vegetables in brine (easy to come by) gives you plenty of Vitamin C, probiotics, and B vitamins.

Once the colony is formed, the fish and sea vegetables will need to come from smaller crafts sent out for gathering. Why? Because of the human waste generated by the colony that goes into the surrounding ocean. Yes it helps feed plants and animals but it's not sanitary to harvest directly from it.


Fresh water is a much bigger problem. Mostly this is for drinking/cooking. While humans feel better bathing in fresh water, it's not required. When there is heavy rainfall, the excess fresh water can be used for laundry and cleaning to get salt residue off.

Rain is uneven and you need enough fresh water storage containers to carry you through to the next heavy rainfall. Dew and condensation collectors can help bridge the gap. And there could possibly even be desalinization technology that works on the right scale to make a difference.

The main issue here though is time. Not just the time between rainfalls, but time ruining your equipment and damaging your storage containers. Plastic containers won't last 150 years (they probably won't last 20 years, especially if exposed to the sun). Metal containers will corrode and develop leaks. They can be repaired, but eventually the patches aren't going to do the trick.

Collectors also will develop holes and leaks. Something as simple as a hanging tarp to allow dew to form overnight and drip into a bucket will not work in a few years because the materials have degraded so much (and can't be replaced). Desalinization equipment will also break down.


Cannibalism can take two forms:

  1. Deliberate "culling" of people for food.
  2. Making use of the bodies of people who have died.

Either way though, it doesn't make much sense. There's no need to eat human flesh because there will be plenty of fish in the sea, even after 150 years of local eating.

Population control is a big issue though and there won't be any birth control available after the first few years, aside from periodic abstinence (which works better than people think but only if you care, chart, and don't cheat). That's not cannibalism but it may give your story the right amount of horror you want.

There is also the issue of criminal behavior. There could be some prison space (perhaps even a prison boat) but it's not practical to punish people by locking them up long-term. For people where "community service" and plain old shunning/shaming doesn't work, there might be a death penalty.

If you really want some cannibalistic element, use prisoners' bodies to feed the fish farms.


The number of people you can have will depends obviously on the capacity of each ship plus how many ships you have. Some ships might need to be workstations or for storage. If not, then you need to allocate space for those things within ships. Ditto for food and water storage, food processing, and general storage.

Food supplies won't limit the population (it does on Earth now but your ships will only have a fraction of what Earth has). But water supplies will, especially as your storage capacities diminish over time.

  • 1
    $\begingroup$ The rhythm method does not work at. all. However, selective sterilization of your population would work just fine. $\endgroup$ Commented Jun 24, 2019 at 19:24
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    $\begingroup$ @CarlWitthoft, sure it does. It's 75% to 87% effective, we just don't tell people it's safe because we have much better options, and people don't always do it properly. If you have no other option, it's pretty good. [1] webmd.com/sex/birth-control/rhythm-method $\endgroup$
    – coagmano
    Commented Jun 24, 2019 at 23:59
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    $\begingroup$ @CarlWitthoft – if used with measurements, it's more effective than condoms (perfect use failure rate of 0.5% vs 2% for condoms) – though the study has limitations (nhs.uk/news/pregnancy-and-child/…) $\endgroup$
    – Dan W
    Commented Jun 25, 2019 at 13:56

The aircraft carrier will not last that long.

A standard cruise is maybe 2 years at a time before needing maintenance downtime in the yard. But during those 2 years there will be numerous resupplies, either at dock or using an auxiliary resupply ship in a maneuver called "UNREP" (Underway Replenishment). That supply ship is not a small boat.

UNREP resupply at-sea

20-25 years before the reactors need to be refueled. Planned service life 50 years with all the planned maintenance periods in dry dock. Maximum? Probably 65-70 but it would be in horrible shape by then.

GW getting propellers replaced

Ships that old stuff like toilets, air conditioning, etc start breaking down. There are WWII ships that old still intact as museums but aren’t operational or seaworthy in any sense. The older the boat, the more expensive and difficult it is to maintain. This is not a good plan, it’s just too much work to keep aircraft carriers working.

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    $\begingroup$ I think you are forgetting that these boats will not be preforming standard military procedure. Instead of almost constantly running the engines, sailing across the world, and dealing with hurricane level storms, they would pretty much float in the northern cool seas. They also would disable majority of the systems usually onboard, (aircraft being the obvious one). People cleaning and anti fouling the hulls underwater is possible, it would just take longer and be harder then if it was on land. Luckily we will have a population with a lot of time on their hands. $\endgroup$
    – Alex
    Commented Jun 27, 2019 at 14:08
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    $\begingroup$ Even at reduced optempo, you still need like at least 50% of the ship's company. Reactor crews, galley, laundry, navigation, damage control... I'd say 1,500 trained sailors at a minimum of the 6,000 possible or any fire or hazardous situation is going to get out of control. You'd be better off starting with like a cruise ship built with human luxury in mind and convert some of the spaces to more permanent habitation - some hospital space, some growing space, etc.. smaller crew, more automation, easier maintenance. Just my $0.02 $\endgroup$ Commented Jun 29, 2019 at 2:28
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    $\begingroup$ Like, the actual "living space" on an Aircraft Carrier is quite spartan. You get a very small rack to sleep on and some space for your clothes and personal effects. That's it. Yes, there are people that love it but there's not exactly a "honeymoon suite" (maybe the Officers / Chiefs staterooms?). $\endgroup$ Commented Jun 29, 2019 at 2:33

Many of the answerers have done a good job pointing out the deficiencies in trying to keep a group of nuclear carriers afloat and functional for many years. However, I think we are giving short shrift to the problems of food, waste management, and public health. The crews of modern warships are generally extremely healthy young individuals, and every effort is made to maintain "herd health."

This will go out the window in a crisis situation with a non-military refugee population. Especially since the medical supplies will eventually run out and it's extremely unlikely any of the ships in the group will have any capacity for making more.

Completely apart from the terrible virus they think they are escaping, if they stay in those close quarters for long, disease will eventually become rampant and wipe them out.

Additionally, warships aren't designed to recycle their waste. They just hold it until they can conveniently get rid of it. Establishing some kind of reasonable waste recycling may be difficult or impossible in a refugee situation.

And even though several posters have claimed that food won't be a problem, a fish-only, protein-only diet will be... less than optimal for everyone's health over the years. The populace will need vegetables, and that requires at least an acre per person. More, to support the possibility of an increasing population and as a hedge against some crops failing.

The right solution is to stay at sea only long enough to find a reasonably isolated and "clean" location on land for most of the refugee group. That alone will be a huge task in such a setting, especially since most of the rest of the populace ashore may be assumed to be quickly dying off and unable to report on conditions. Time would be of the essence, and this would likely be a time (and resource) consuming task! Perhaps this could be the crux of the story?

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    $\begingroup$ "The populace will need vegetables" The Inuit were/are reasonably healthy on a vegetable-free diet. Vegetables are good, but not essential. $\endgroup$ Commented Jun 27, 2019 at 9:00
  • $\begingroup$ Welcome to the site! First off, waste management seems to have a pretty clear answer, dumping, or composting. Composting human waste can get pretty gnarly though, but with modern knowledge of decomp. it should be possible to carry this out effectively. There is no isolated clean location on land, as stated in the question. Also, with proper hygiene it is possible for people to live in a tight space without contracting communicable disease. If someone is found to be sick at the extremely routine medical checkups, they will be moved to a smaller quarantined vessel, or thrown off the boat. $\endgroup$
    – Alex
    Commented Jun 27, 2019 at 14:15
  • $\begingroup$ @MartinBonner, good point. If I recall correctly, the Inuit get a lot of their vitamins and other micronutrients from dishes such as Kiviak (made from fermenting Auks within a sealed seal skin, no pun intended). But there have been some recent deaths from inexperienced people trying to make it: it has to be done exactly right or it's poisonous. That actually could make an interesting plot point. Ship's doctor realizes their vitamin supplements are dwindling and someone mentions making a kiviak-like preparation. It takes several tries (and several near fatalities) before they get it right. $\endgroup$
    – Forbin
    Commented Jun 29, 2019 at 1:43
  • $\begingroup$ @Alex, I just stumbled across my post and your comments and re-read them. I find I must differ on only one small point. "There is NO isolated clean location on land." The OPs statement "there is no landmass uninfected" notwithstanding, the reality would be more likely "there are no SIGNIFICANT landmasses uninfected (except Antartica)." There are uninhabited islands scattered all over the world, and unless the virus is airborne and either absurdly hardy or permanently a cross-species infector, at least the most isolated of these islands will likely be clean. $\endgroup$
    – Forbin
    Commented Jul 2, 2021 at 15:39

Could some number of people survive without resorting to cannibalism? I think the answer is most certainly. Could 7 Billion people survive off harvesting the Pacific Ocean for 150 years? On average humans need 100 grams per day and 1500 calories. That's 700,000 kg per day of protein and a lot of calories. Today, we harvest 90 Billion kg of fish, muscles, and so on from all the seas around the world. So there seems like there would be enough food for a lot of humans. Survivability would be enhanced by colonizing the other oceans too, and not just the Pacific.

I think the biggest challenge would be power generation. They'll need to smelt metal to repair parts of their ships -- 150 years at sea is a long time, and ships rust.


Assuming no issues with the ships ventilation as stated by JBH, here are some solutions.

If your goal is to ensure the survival of humanity

Just do Adam and Eve for each ship. If each ship have a plot of land and fish, a pair (a male and female), they continue the human race; especially if there are multiple ships out in sea. Ideally, you would want a doctor or medical expert to be either the husband or wife and some specific vitamins to make up for the missing resources provided by eating meat.

Since there's only two human per ship, you can even bring in livestock like cows and chicken as they produce useful food items. Heck, if each ship brings a different combination of livestock and/or plants, they can implement a trading system where each ship (or family) can trade with other ships for essentials. This will ensure that each ship is specialized in one produce.

As for who gets to live and who gets to die, well, that's where this gets a bit nasty; it is the survival of the fittest. Those who are the healthiest and have useful skills (i.e. doctor, farmer, fisher) gets to live. While pairing should be compatible/lover, with the end of humanity, lovers can't be choosers.

Save as much people as possible

There are multiple suggestions of fishing/farming, but here is another, very disgusting, albeit doable way.

This is pretty bad, you have been warned

Eating one own poop could help offset some food issues provided that medications are abundant. This is because the digestive system cannot 100% process what we eat fully and thus our waste still have some benefits. There are health risk with this obviously, but that is where medication comes into play. Meds are generally small and last a long time. The idea is for the rest of the years, carefully balance fishing/farming and eating poop to survive. And every other or so excretion gets reused as food (obvious for oneself, it is already bad as it is, but force other to eat yours?).

The main idea is not to exhaust the sea and whatever land you have. Over fishing and and planting can greatly tax the resources and led to early depletion of resources. So by limiting the amount of fishing and farming via other means, one can last longer. Also, the waste can be used as fertilizer to help rejuvenate the land and with careful amount, attract micro-organisms which can then attract big predators, leading to more fishes.

The reason I did not mention bring livestock in this case is that humans + livestock = too much waste and thus cause heavy pollution which can easily led to quicker contamination of water and air. Especially cows.

Screw the World

This one is pretty much ignore the disease and move back to land. Humans are very adaptable creatures and a group of people may be able to become immune to the disease.

To help with this crazy idea, lets go even crazier. Radiate people; you got nuclear reaction at your fingertip. Mutation can lead to genes which could help the person survive the disease. What kind and how much? That is up for grab and chance.

Would not recommend if you want to see humanity live; would be a fun simulation tho.

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    $\begingroup$ You may want to read up on minimum viable population. Apart from that: Just one pair per ship will cause problems (isolation: humans are social creatures). Also: Overfishing won't be an issue for a few tens of thousands of people. The oceans are big. $\endgroup$
    – Burki
    Commented Jun 25, 2019 at 8:45
  • $\begingroup$ Also: inbreeding! $\endgroup$ Commented Jun 25, 2019 at 19:52
  • $\begingroup$ That is true that two per ship may be low, but the idea is to start small. Something like tiny villages on the sea. They would be able to trade with one another so that could be a form of contact. $\endgroup$
    – BahJiy
    Commented Jun 25, 2019 at 20:07
  • $\begingroup$ Inbreeding may work, but I remember reading about some issues with the genes. The children can always breed with the children of other ships if needed. Inbreed would be last resort if the ship is stranded or is the only one left. You only need 3-4 generations before 150 years pass if you delay breeding. $\endgroup$
    – BahJiy
    Commented Jun 25, 2019 at 20:10

Cannibalism just doesn't work in that setting. It can be a solution for relatively short periods of times. Maybe for a year or two (stranded in north pole or surrounded by enemy soldiers for less than a year) but eating people will cause serious issues. First of all is the amount of human meat in a body. Assuming things are not going well the average weight of average person on that ship has gone down to 65kg on average. Men and women alike lost their body fat and become more more fragile, skinny and tired. And people won't start eating other people until they have done and waited as long as possible. This means that average body has less stuff to eat. According to some googling about 80% of human body weight is edible. So one body is about 52kg of food. And one kilogram of human meat might have 1500 calories.

Using gerald r ford aircraft carrier as an example that holds a crew of 2600. So let's assume we triple that mount and remove all the airplanes and weapons to make it still float. That is 7800 people. Pure guess. Let's say 700 calories per day is minimum to survive. This is awfully low amount as you'd need to be able to work hard to keep fixing the ship as all its systems are massively overloaded due to tripling of the number of people onboard. But you have kids onboard as well who eat less.

So from those numbers we can quickly conclude that relying on cannibalism alone won't work. Daily for that amount of people you'd need 5200kg of human meat! You'd need to be killing 56 people PER DAY just to survive. It just doesn't work at all. If you want a math challenge you can work out how long until all but one person is dead from that 7800 people. One person needs 700 calories per day, meat has 1500calories per kilogram, one person weighs 65kg.

And if that is not enough you'll create massive problems with who gets to live and who gets eaten. You are asking people to commit mass scale murder on daily basis. People having to eat their spouses, kids, mothers and fathers. Not to mention the effort it takes to prepare all that food. Killing, cutting it up, cooking it... You don't want to eat raw meat as it has less calories than cooked meat. So you need a lot of electricity or wood to heat up the meat as well. Plus all kinds of other issues. When the food runs out cannibalism won't save you. It might help handful of people out of big group to live a year or two longer at most.

  • $\begingroup$ "80% of human body weight is edible" - that is probably 80% of a healthy-weight adult. I am currently 75kg, so 60kg edible and 15kg in-edible. If I lose 15kg, that will pretty much all come from the edible portion (not the bones), so 45kg edible/15kg inedible. - So it's even worse. $\endgroup$ Commented Jun 27, 2019 at 9:05

The reactors are not designed to last that long. When the fuel goes your people will probably suffocate in the lower levels and youll drift uncontrollably. Your people will not survive after that. I think the fuel lasts about 25 years. If these reactors are breeder reactors that turn u238 into pl239 then your all set. The ocean has a lot of uranium dissolved. They should be able to build drones out of scrap that can be used to harvest iron from land, and sterilize it before bringing it over. Then turn the iron into wires and run some dc current through it. It will turn into a substance similar to concrete by mineral accumulation and will self repair so long as it has dc current. You now have concrete floating islands ideal for coral growth and aquaculture. Fishing and algae can be used to make more soil. After a bit youll be able to make concentrated solar thermal generators. Your floating islands are now sustainable and capable of growth and will ladt longer then the fuel in your carriers, which will probably be disassembled.


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