Countryistan is a large island nation approximately 3,000 kilometers from the nearest landmass.

The government of Countryistan is secretly planning on committing genocide and ethnic cleansing against a portion of its population in about a decade.

A powerful billionaire/member of the ruling party who's secretly sympathetic to said portion of the population, and who knows what's going to happen, happens to own an oil company which owns an ultra-large crude carrier - a huge ship designed to transport enormous quantities of unrefined crude oil.

Said ULCC is currently in a high-quality shipyard specially-built to accommodate it. It is intended to leave within a year or two on a shakedown cruise to a nearby country; however, the billionaire and the higher echelons of their company are constantly sabotaging it in order to cause enough of a delay for it to be retrofitted.

Said billionaire wants to turn said ULCC into a transport, fill it with the people most likely to be murdered by the government, and then send it on its 3,000-kilometer cruise. Once it and its passengers arrive in a safer place, it simply won't come back - or, maybe it will, minus its passengers, and it'll just keep going back and forth until the plot gets found out.

This billionaire and their company have the resources to keep government inspectors away from the ship - they own a good portion of the country's shipbuilding industry, but have little power otherwise due to deliberate factionalism within the ruling party. They can do many things covertly, however; money talks.

For the purposes of this question, the ship is the Seawise Giant. It has the following characteristics:

Additionally, it is nuclear-powered, with a reactor/turbine combination that puts out as much horsepower as the real-life Seawise Giant's engines. In-universe, this is seen as perfectly normal and not suspicious. It does not require refueling within the timespan of this question.

How do we modify this ship to carry the maximum number of people possible, taking into account the following conditions?

  • The ship has to look the same on the outside as it would if it were unmodified - both above and below the waterline. There can be no extra structures on the deck, no holes in the hull, and nothing, visually speaking, that gives away the fact that the ship is full of refugees, or, for that matter, invites any form of suspicion.

  • The ship has to displace roughly the same amount as it would if it were empty and unaltered, because, if it rides too low or too high in the water, it'd be suspicious-looking. A small margin of error is acceptable here.

  • The ship has to move as quickly as it would if it were empty and unaltered, since if it was moving slowly, it'd draw suspicion (and also require more supplies for the refugees). This means 16.5 knots, bar a small amount that could be explained away as engine trouble.

  • Anything that does not change the outside appearance of the ship, its displacement, or its speed is fair game. For instance, the guts of the ship can be pulled out and replaced with their weight in people and supplies for said people, and blocks of concrete or steel can be put on board in order to add enough weight to make it settle in the water correctly.

  • People should not die en-route, other than by accident or things they were already going to die of. If someone dies of cancer, that's fine. If someone dies of dehydration, it's not. It will take 98-ish hours for this thing to get from Point A to Point B, and probably another 12 on either end for loading and unloading. No simply packing people in like sardines; there has to be enough room to sit down, enough below-the-deck restrooms for people to use the bathroom, adequate ventilation, food for about 5 days, etc. It does not need to be comfortable, though; it just needs people to not die/go insane long enough for it to arrive on-target.

  • Your budget for modifications is equivalent to $20 billion in present-day dollars.. The ship itself, the nuclear reactor, shipyard, provisions, operating costs, and the like are all accounted for; this budget is only for modifications. The shipyard facilities are top-of-the-line.

  • To reiterate, the nuclear reactor and the subsequent lack of exhaust are seen as perfectly normal, and not suspicious.

  • The ship is already fully built. It will need excessive reconfiguring in order to serve its purpose.

  • You have 9 years to get these modifications finished. I believe this is reasonable, considering that Seawise Giant was built within 5 years.

  • Getting these people on board isn't a problem. The billionaire and the company just pretend to be killing the people, they disappear (in reality, via the ship) and the government doesn't figure it out.

  • Getting these people off the ship isn't a problem either. The billionaire and their company have set this up in advance.

  • Assume Earth-standard conditions - for instance, approximately 9.8 m/s^2 of gravity, 101.325 kPa air pressure at sea level, human-breathable atmosphere, seas made of water, etc. Additionally, assume a modern-day tech level.

I will add more to/edit these requirements if someone points out a glaring absence in/flaw with them.

And don't you tell me that anything less than 8,000 can fit on it once it's retrofitted; the world's largest cruise ship can fit more than that, it's smaller than this thing, and its design prioritizes comfort over efficiency.

  • 3
    $\begingroup$ ??? 600,000 / 50 = 12,000; or 600,000 / 30 = 20,000. So, 12,000 to 20,000 people, easily, depending on how spartan or lavish the conditions are to be. Just make a rough estimate of the gross volume per person. Or do you want the story to be about the design and building of the new ship? (And it will be a new ship. Oil tankers are designed to carry a load which is actually lighter than water. They are little more than thin shells intended to keep the oil from mixing with water and float away. You will need to rebuild the ship from the keel up.) $\endgroup$
    – AlexP
    Feb 9, 2022 at 9:31
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    $\begingroup$ Do you allow the people to come up 'on deck' once the ship is underway? Also, If you are still wont to revise the story, then you might be better off with a container ship than a tanker. They can be much, much bigger, are definitely variable in loaded weight, and come already with 'cabins'. Not much revamping necessary. 21,718 20-foot containers, say 10 people per container, then over 200,000 people easily. $\endgroup$ Feb 9, 2022 at 15:00
  • $\begingroup$ @JustinThymetheSecond No, they don't get to come up on deck. Container ships have an issue in that they won't be carrying any containers on the outward trip. $\endgroup$
    Feb 9, 2022 at 15:53
  • 3
    $\begingroup$ They ALWAYS have to return the containers to where they came, otherwise they just pile up on the island. $\endgroup$ Feb 9, 2022 at 16:24
  • 2
    $\begingroup$ Do external modifications below the water line count as changing the outside appearance of the ship? They wouldn't be visible at sea, but would be obvious to anyone seeing the ship in drydock. $\endgroup$ Feb 9, 2022 at 20:19

7 Answers 7


"It was sad when the great ship went down."

Moter Vehicle Wilhelm Gustloff was sunk on 30 January 1945 and thousands of people drowned.

The figures from Schön's research make the loss in the sinking to be "9,343 men, women and children".[22] His more recent research is backed up by estimates made by a different method. An Unsolved History episode that aired in March 2003,[4] on the Discovery Channel, undertook a computer analysis of her sinking. Using maritime EXODUS software,[23] it was estimated 9,600 people died out of more than 10,600 on board. This analysis considered the passenger density based on witnesses' reports and a simulation of escape routes and survivability with the timeline of the sinking.[24]


Considering how many more people there were aboad than on a modern cruise ship, one might imagine that Wilhelm Gustloff was gigantic.

Wilhelm Gustloff had a GRT of 25,484, and had a length of 208.5 meters (384 feet 1 inch), a beam of 23.59 meters (77 feet 5 inches), a height of 56 meters (183 feet 9 inches), and a draught of 6.5 meters (21 feet 4 inches).

So it held 2 or 3 times as many people as a large modern cruise ship in only about 10 percent of the space.

The passengers were mostly German refugees fleeing in terror from the advance of the vengeance-crazed Red Army, so they didn't mind being packed in.

Of course the planned voyage of Wilhelm Gustloff was a much shorter distance than about 3,000 kilometers.

I think that the planned voyage of the Wilhelm Gustloff would have been less than 300 miles or 483 kilometers. At a speed of 15.5 knots or 28.7 kilometers per hour, or 17.8 miles per hour, it should have taken less than 17 hours for the planned voyage, and possibly a lot less time if the destination was significantly closer than 300 miles or 483 kilometers. So the passengers would have been willing to be crowded and have inadequate facilities for such a short time.

But the voyages in the story would be a lot longer, about 3,000 kilometers, at a speed of 16.5 knots, or 30.558 kilometers per hours. Such a voyage would take about 98.17 hours, or about 4.09 days. So the passengers would need much more food, water, and air, and much more facilities, for the voyage, especially if some of them were not in terror of being exterminated.

Another historic example of a crowded ship is the Chinese junk Tek Sing, which sank on February 8, 1822.

The Tek Sing (Chinese, "True Star") is one of the few "Asian vessels discovered in Southeast Asia [that we know its name, for] "generally neither name nor date is known. The Tek Sing is an exception."1 Generally, shipwrecks are named either after a landmark or location near where they were found or the cargo they held. She was a large three-masted Chinese ocean-going junk which sank on February 6, 1822 in an area of the South China Sea known as the Belvidere Shoals.[2] The vessel was 50 meters in length, 10 meters wide and had a burthen of about a thousand tons. Its tallest mast was estimated to be 90 feet in height. The ship was manned by a crew of 200 and carried approximately 1600 passengers. The great loss of life associated with the sinking has led to the Tek Sing being referred to in modern times as the "Titanic of the East".[3]

So the Tek Sing was 50 meters (164 feet) long, and 10 meters (32.8 feet) wide.

So the main deck of the Tek Sing should have had about 500 square meters. With about 1,800 people aboard that would give about 0.27777 square meters (2.99 square feet) per person. If it had 2 decks there would have been 0.55555 square meters (5.98 square feet) per person, three decks 0.83333 square meters (8.97 square feet per person) per person, four decks 1.11111 square meters (11.96 square feet) per person, 5 decks 1.3888 square meters (14.95 squae feet) per person.

And maybe a lot less if the cargo of Chinese porcelain took up a lot of space that people could have occuptied.

The Tek Sing was sailing, repeat sailing from Xiamen, China, to Jakarta, Indonesia a distance which I estimate to be about 2,100 miles or about 3,379 Kilometers. It sank in the Gaspar Strait, most of the way to Jakarta, after about a month of sailing.

So the approximately 1,600 Chinese immigrants on the Tek Sing were willing to endure a month of sailing in crowded, unsanitary conditions on it, for several times as long, maybe 10 times as long, as the refugees in your story would endure conditions on their voyages.

Of course if your world is advanced enough to build a late 20th century type vehicle the size of the Seawise Giant, the people in it might have become too refined and spoiled and dainty to endure such conditions even to save their lives from genocide.

Added Feb. 10 2022.

The Seawise Giant was 458.45 meters (1504.10 feet) long and 68.6 meters (225.07 feet) wide. So its deck area was approximately 31,449.67 square meters or 338,57.78 square feet.

That is approximately 6.394 times the approximately 4918.515 square meters of the Wilhelm Gustloff's deck area and approximately 62.899 times the approximately 500 square meters of the Tek Sing's deck area.

If it has as many decks as the Wilhelm Gustloff and is as crowded as the Wilhelm Gustloff, it could carry approximately 67,777.875 people.

If it has as many decks as the Tek Sing and is as crowded as the Tek Sing, it could carry about 113,218.81 people.

And those rough calculations might give an idea of the approximate upper number of people who could be carried under some conditions.


If we go with a useable volume of 600,000 m³, based upon the ship's crude oil carrying capacity, we could allocate 1 ton and 2 cubic metres per person that it will be refitted to carry. This is approximately the same volume allocated per man in age of sail warships... which would likely be a bit too cramped when AoS crews could get out of their hammocks and do a bit of outdoor manual labor, but these refugees must stay inside.

Allocating 1.5 tons and 3 cubic metres per person would include a bunk bed, provisions, shared head/mess/galley/recreation areas and nuclear powered air conditioning. The sleeping arrangements would be cramped, and the recreation areas wouldn't be terribly large, but they'd allow the passengers to get a bit of exercise and avoid DVT from long periods of inactivity. The food would be largely pre-packaged and bland, but it would keep the passengers alive for a couple of weeks, more than twice as much as expected. So, with 600,000 m³ of volume, we'd have space and supplies for 200,000 refugees.

Allowing 2 tons and 4 cubic metres per person for 150,000 refugees would approach the conditions experienced by passengers in steerage on an early trans-atlantic passenger ship (or better, considering that they wouldn't have air conditioning), and when the goal is to carry as many passengers as possible on a relatively short trip of 5 days, this may be a bit too much luxury.

To make up for the difference in mass between passengers and its supposed crude oil cargo, the ship could take on ballast water. Modern ships are designed to do so, no refitting necessary.

Refitting the ship for this purpose could easily be achieved in the allotted time of 9 years... probably in a third of that time, or less, and definitely for well under 20 billion. In fact, 1 billion would probably cover the costs nicely.

I've also used the figure of 600,000 m³, less than that which the OP has said is available, in order to use the remaining volume to modify the ship's structure and if necessary its power plant, in order to compensate for the different mass distribution and higher power requirements, though the existing nuclear power plant should easily be capable of supplying the required power, since such plants are typically over-engineered in order to avoid stressing them.

If this ship is intended to carry its passengers on its maiden voyage, and it needs to look unloaded, just move the plimsoll lines so that they're well above the loaded eaterline and run with minimal ballast. Move the plimsoll lines again for the return to dock to account for the altered load and take on ballast water, if necessary.

  • 2
    $\begingroup$ @Rekesoft Not so... these ships must be able to handle rough seas both loaded and unloaded. Oil is still a pretty heavy cargo. With the size of these ships, plus the seperate hull and tanks, they aren't that weak. $\endgroup$
    – Monty Wild
    Feb 9, 2022 at 11:13
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    $\begingroup$ Obviously the "thin layer of metal merely preventing mixing oil and water" was an exaggeration, or they would made oil tankers like plastic bags, but still, if you completely change the load requirements of a ship, you end up with a completely different ship. You can't just refurbish the interior a little bit and pretend the ship is going to work. To start with, you maybe can cramp 200,000 human corpses in 600,000 cubic meters, but if they are alive they will remain so until they run out of oxygen and the heat reaches 50ºC - a bit less than an hour. $\endgroup$
    – Rekesoft
    Feb 9, 2022 at 11:19
  • 1
    $\begingroup$ @Rekesoft That's why I said that that volume would include air conditioning. There's a whole nuclear power plant from which to run it. Also, ventilation is pretty easy to conceal - just make it look like the ship's ventilation, but run more air through it. That $1b would include appropriate reinforcement. I did take a bit less than the minimum tankage as the useable capacity for a reason... $\endgroup$
    – Monty Wild
    Feb 9, 2022 at 12:15
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    $\begingroup$ Remember that nuclear doesn't mean "magic". If you have a nuclear engine capable to propel a 60,000t ship at 12 knots, and now you have also to provide ventilation and refrigeration for 200,000 passengers... don't expect more than 2 knots of maximum speed. Nuclear engines, like diesel engines, have some power output you could measure in horsepower or watts, it doesn't mean that you have an infinite amount of power. $\endgroup$
    – Rekesoft
    Feb 9, 2022 at 14:18
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    $\begingroup$ @Rekesoft Oil is about 85% the density of water/humans. Unless you pack in humans to fill more than 85% of the oil tank volume (which seems terribly unrealistic), the human cargo weighs less than the oil cargo. Allocating 0.85 tonne per cubic meter of passenger volume yields the exact same weight as the 0.85 tonne per cubic meter of oil. Oil is less dense than people, but is much better at filling the volume. $\endgroup$ Feb 9, 2022 at 16:00

In order to have a plan like that you need to have a good idea of how many people you need to kill off, that means keeping close tabs on your general population and closer tabs on the ones you think you might want to do away with. In short the government have to run a fairly competent surveillance state to even consider this plan if people have any normal freedom of movement. Which makes the limiting factor not the carrying capacity of the ship, which I put at a minimum of 26,000 for the hold alone (that's based on how tightly they cram crew into a Skipjack nuclear submarine so the final total is going to be much higher; there are no weapons systems and they need far less provisions per head for the short trip overseas than a 6 month patrol), but how many people the company can spirit away to the ship before the death squads show up on the docks.

  • 1
    $\begingroup$ The government isn't really competent, due to the factionalism I mentioned; it's just that they're, y'know, 3,000 kilometers from land, and people can't really get away. The company can get these people onboard; that's not the problem. $\endgroup$
    Feb 9, 2022 at 7:26

It's easily possible

The Seawise Giant (now Knock Nevis) is a double hull tanker. If we remove it, we'll have a lot of extra weight we can use. If we use lightweight materials like some carbon fiber polymers we can make a whole ship that approximates the right weight unladen. It is more difficult to make it correct when it should approximate fully loaded.

The nuclear reactor can solve a lot of problems. You need sunlight lamps, air recirculation, purifying and some fresh air, cooling/heating, water purifying and more. All can be done with the nuclear power. It'll even make too much energy and easily power the engines as well.

With all the piping on top of the ship it should be possible to make many connection pipes look closed, while they actually suck in fresh air or something. Under the ship you can have compartments that open and close to let in water you'll purify, reducing the chances anyone somehow looking under the ship will notice things aren't what they seem.

There's 650.000m³ of space available. In submarines a person has about 1.4m² space, just enough for a bed and to store a fee belongings. Add a bit extra for xommon areas and facilities and we can come to about 2m² space per person. With a height or roughly 2m that is 4m³ per person. 650000/4= 162.500 people. Lets remove some for extra storage, facilities and maybe the exact measurement doesn't allow for an extra floor or something. Add in some extra space for the nuclear reactor that will probably need more space than the current engine and we'll have 140.000 people left as a very rough estimate.

This is cramped, but there will be place for recreation, eating and other things.

The only problem is that you either need to pretend the ship is never at carrying capacity or you need to have a lot of heavy ballast you can transport. Using lead or something you can add weight, but you'll lose a lot of compartments. Lead is about 8,7 times as heavy as oil per volume, so you would need 1/8th of your living space to be used for weight. This needs to be added and removed, possibly moved by other ships the other way again. That means about 122.500 people can come with. Still quite a lot.


The Seawise Giant is a double hull tanker. You can remove a hull, make a compartment structure of lightweight materials and storage to approximate the empty load of the tanker correctly. Nuclear power should be enough for the engines and any commodities like loght and water purification. Very roughly 140.000 people can be moved. Might be much lower if you want to pretend a full load, making it 122.500 per trip. Weights would need to be moved back separately as well.


The primary retrofit issues are "hotel services". If you are keeping 30k people below decks you will need to provide :

  • Sufficient ventilation for breathing and heat exchange - at least 10 changes / hour. Aircraft run about 20 changes / hour.

  • Waste disposal / sanitary facilities

  • Seating / sleeping

The machinery for this will occupy significant volume. The ship's existing propulsion plant will be insufficient to power this as it will have been sized to deliver propulsion and auxiliary power for the vessel as specs. BTW load / light does not make much difference to the fraction of propulsion power drawn at sea speed. It's not about mass it's about wetted surface area. Additional generating capacity will be required.

At an average of 80kg 30k people mass about 2,400 metric tons.

Mass is not your problem. Assume that each person will occupy 4m3. Allow 100% for access.

There will need to be intermediate decks fitted in the holds as there will be insufficient tank top area to accommodate your people.

Also food for the voyage will need to be supplemented by food for the loading period. How long are you planning on taking to load these folk?

If this is a country with an oil industry have you thought of sneaking people out on crew boats? That might be simpler?

  • $\begingroup$ Crew boats going back and forth constantly would raise more suspicion then the tanker going back and forth constantly, since Countryistan has closed its borders but not stopped the oil trade - there's no reason for crew boats to constantly be moving back and forth, but the tanker has a reason. Also, I just want to turn a ULCC into a refugee carrier. $\endgroup$
    Feb 9, 2022 at 18:11

I feel like the answers here assume small hotel rooms for the people. I don't think this operation would look like this:

capsule hotel

I think you can achieve higher density, and more lives saved, by taking this approach:

afghanistan plane

The image is disturbing, but that is what people do when evacuating from a hostile country. Sure, that plane trip was less than a day, but to survive for 98 hours, all you need is water and fresh air. Privacy is a luxury.

I suggest you put people lying side-to-side, have them exchange water bottles and pee bottles between them. This will not be comfortable. But it will save lives.


To allow for walkways and the engine; I take the low end of that capacity, 500 000 cubic metres. The smallest volume that physically fits a person (40 cm wide, 30 cm high, 200 cm long) takes up 2.4 m^3. That means you can have 210 thousand people on that boat.

  • 1
    $\begingroup$ The slave ship layout won't do. Humans need the ability to change position once in a while; without that, they will develop or worsen health conditions, so you'd have deaths. The Kabul-Qatar flight was 3 hours, even sitting down cramped is going to be pretty marginal for 96 hours. $\endgroup$
    – toolforger
    Feb 10, 2022 at 11:17
  • $\begingroup$ @toolforger There would be health conditions, sure. A few pressure ulcers, possibly muscle atrophy in need of rehabilitation on the mainland. But I don't see how a healthy individual could die from lying in a bed for 100 hours. $\endgroup$
    – KeizerHarm
    Feb 10, 2022 at 11:42
  • $\begingroup$ 96 hours of lieing still do not create muscle atrophy or open pressure ulcers (the first, harmless stages start after roughly 2 hours though, and people start moving their body weight around long before that). $\endgroup$
    – toolforger
    Feb 10, 2022 at 12:17
  • $\begingroup$ however, the main point is that the refugees are not generally healthy. The goal is to save everybody, and there are bound to be some who are more vulnerable and simply won't survive. Imagine somebody with a combination of bodily weakness (elderly, seriously ill) and very, very seasick - they might asphyxiate on their own vomit, and if they are one row away from free space, nobody will be able to help quickly. Remember you can't choose evacuees, you want to save everybody who comes, including the weak, ill, and claustrophobic. $\endgroup$
    – toolforger
    Feb 10, 2022 at 12:22
  • 1
    $\begingroup$ Another problem: Packing people will - marginally! - work for 3 hours, but not for 96, and not if you pack 10-100 times the amount than in that plane; there's always that person who just can't hold their water, or develops diarrhea while on the trip. Also, people need to get to defecate if it's 96 hours, pee bottles solve only half of the problem (plus there's always the mishap where a bottle drops, and if it's as cramped as in a slave ship it won't get cleaned up - look up the WP article to see what conditions developed). $\endgroup$
    – toolforger
    Feb 10, 2022 at 12:34

Make the ship a part of the murder plans

This isn't an answer to your exact question, but I wanted to provide an alternative angle which might reduce your challenges. Instead of trying to hide everything, you could opt hiding for one thing:

Contact the goverment (in a secret back alley kind of way ofcourse) and offer them your boat (ofcource for a nice reward (money, power, ...), not asking anything would be weird) and plan with them to make the boat sink with all those filty people in it!

They now have a nice way of transporting all those people (because why would the goverment care about comfort?) and you dont have to expect inspections, because why would they inspect you, you're on their team! All that paperwork will be handled upstairs.

You offer a nice location, which just happens to be passed a nice island to offload those people, where you will make the ship sink!

The ship does actually sink with all people on it while the evil goverment is watching, hearing all the screaming! Satisfied they go home.
What they didnt know: All passengers got an provided air tank and can just wait a while and be picked up later.

  • $\begingroup$ Nice idea but has issues: 1 it's just a one-way trip, 2 if making it a repeat trip (e.g. "we'll throw them overboard") the time to return to port will be suspiciously long (200 hours+, you don't need that long if you just move out of sight). Might work if you build 100 ships and pretend it's one that returns every two hours, but in reality it's a chain of 100 ships doing roundtrips (probably hits budget and time limits though). $\endgroup$
    – toolforger
    Feb 10, 2022 at 12:25
  • $\begingroup$ 1. Why returntrips? You can fit a lot of people on ship like that if you dont care about them. Not very pleasant, but I'm guessing not-dying is worth a little discomfort. 2. no returntrips needed :) $\endgroup$
    – Martijn
    Feb 10, 2022 at 13:02
  • 1
    $\begingroup$ If you need multiple trips you still dont need multiple tankers, you let the tanker just roundttip to the drop point, where other (hidden, submerged?) ships wait. $\endgroup$
    – Martijn
    Feb 10, 2022 at 13:03
  • $\begingroup$ Re 1: Well, the billionaire obviously cares about them. "A little discomfort" isn't really viable, he needs to think about refugees that are ill, disabled, or panicky, because then there will be deaths, which is what the question explicitly rules out. But you can just openly ferry the refugees on open sea, dealing with the government observers is probably easy (few really want to see people dieing, and those who do are usually not mourned much if they "vanish"). $\endgroup$
    – toolforger
    Feb 11, 2022 at 14:26

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