How small of a boat can sustain itself in the ocean?

Question

So my hero (henceforth Bob) has become disgusted with all that society has to offer. He decides to set sail on a ship, never to return to the mainland supercontinent again (this is WWI tech, so you can assume no one is going to find him in Panthalassa, which is basically a large global sea with mainly small islands, and thought by all others living on the planet to be devoid of habitation. He takes his trusty lieutenant (Alice) and orders them to quickly build a ship with the limited resources of the island. My question is, how small is too small? The seastead/ship should ideally have enough resources (food, water, energy, etc.) to last four or five years at sea mapping a swath of midlatitude ocean and searching for new land. Resources include:

• Food: they don't want to starve, but also providing the full daily values of nutrition (they don't want to get scurvy, AND they don't want to be stuck eating fish for two years)
• Water: they don't want to die of thirst, and obviously drinking seawater isn't going to help them quench it. Remember this is WWI era tech, 1920s if you're stretching it.
• Energy: this planet is similar to Earth and therefore they don't want to be cold while exploring the midlatitude regions. It has to last four years. And of course, nuclear power hasn't been invented yet.
• Memory: Even if they have all of these equipment, they still want to be able to store memory of the old world. This can be waived for answers, but you get bonus points.
• Why: This is also for bonus points, as human-like animals with curiosity, intelligence, greed, etc. slightly below to slightly above humans, why haven't they explored this region with their WWI tech that can take pretty lengthy excursions at a time?

Answer 1

History is replete with examples of long ship voyages. Broadly speaking there are two types of strategies for long-term survival:

1. Highly technological, take everything with you strategy.

2. Low-tech, make things up along the way strategy.

Perhaps a read of the famous search for the NorthWest Passage would be a good starting point for you for the above. The two strategies cannot be more different.

The Franklin Expedition is a good example of the first. Take all your food with you, take as much crew that you can support, the latest technology and some of the largest ships. A large expedition set sail to search for the passage, but ultimately they were marooned, technology didn't work, supplies ran out, and all on board perished.

In contrast Roald Amundsen had a completely different approach (call it strategy 2) where he had a minimal crew, thus requiring less support, almost no supplies but the intention to live off the 'land' where he could. The ship was small, deft and had a low draft. The mission was light-weight. In the end he was the first to discover the passage, his voyage could last indefinitely.

Strategy 2 is best for your intrepid travellers. Living off the sea, with low-tech ships (things that don't break down) ability to navigate by non-technical means. The Maud, Amundsen's ship, was only 120ft long, made of oak.

So to answer your points:

• Food: you have to live off the sea, especially if your voyage is 5 years.
• Water: you need to collect water as you go. A distillery may be an option, but nothing beats collecting rain-water as you need to expect technology to break down.
• Energy: Similarly don't rely on any energy source. It will break down. Instead use sail and wind power.
• Memory: Yes, write it down with a good old fashioned pen and paper.
• Why: Well many have the desire to do this, and many have. The longest non-landing voyager of recent times is Reid Stowe, for 3 and a half years in a small 70ft schooner. Why did he do it? Because he could, some people have it in their nature. Amundsen after making the voyage made an Antarctic expedition and was the first to make it to the South Pole. He just kept exploring.

Answer 2

The power of a real life example: Nansen's Fram

As it happens, there really was a pre-WW1 explorer who engaged in an expedition of several years mapping and studying an ocean; his name was Fridtjof Nansen, and his ship was the Fram.

 

On the left, a photo of Fridjof Nansen in the 1890s; available on Wikimedia, public domain. On the right, a photograph the ship Fram, under sail in Antarctic waters; the photo was taken in Antarctic waters, during Roald Amundsen's South Pole expedition. Available on Wikimedia; public domain.

In 1893, Nansen and his crew of twelve embarked on the purpose-built Fram and sailed to the Laptev Sea, where they let the ship be caught in the polar ice. The ship then drifted with the ice pack for three years, from September 1893 to August 1896, crossing the Arctic Ocean and finally emerging from the ice in the Atlantic near Spitsbergen. For more than three years nobody had known anything about them: when they emerged from the ice it was an international sensation and they became instantly famous worldwide.

The expedition is described in splendid detail in Nansen's book Farthest North, mandatory reading for any exploring boy or girl, and available for free from the Internet Archive. (The book was a great success, and made Nansen a rich man.)

The Fram is a wooden three-masted schooner, powered by sails and (originally) by a 220 horsepower triple expansion steam engine. Today she is on display in her own dedicated museum in Oslo, Norway.

• built in Norway by Colin Archer in 1892;

• 427 tons gross register tonnage;

• 39 meters long, 10.4 meters wide, drawing 4.6 meters;

• served in three long duration polar expeditions, led by Nansen, Sverdrup, and Amundsen;

• the most famous ship to serve in both Arctic and Antarctic expeditions.

Answer 3

A single large, technological ark is probably not going to help. Their endurance - the time or distance they can spend away from port - is just not that good.

Since you specified WWI-era tech, I'll take USS Omaha (CL-4, launched 1920) as an example. US cruisers were designed for long-range operations such as scouting and patrol, and had to be able to operate in vast reaches of the Pacific where bases were few and far between. Its total range before resupplying was on the order of 9,000 nautical miles (17,000 km) at a cruising speed of about 10 nautical miles per hour. That's only about a month and a half if they go 24/7, or maybe three months if they're only moving during daylight hours. If you're looking for fewer people than its complement (400-500) you could stretch your supplies, but not your fuel.

Omaha's "standard" displacement was 7,500 tons, and its "full load" displacement was 9,500. The difference, 2,000 tons, is essentially all fuel and water for steam. (Standard displacement was actually invented specifically to exclude fuel, to make it easier to compare the size of long- and short-range cruisers.) Increasing your range is going to mean dramatically increasing your fuel requirements. You can build bigger, of course. A contemporaneous battleship (say the USS Maryland, BB-46, also launched 1920) could have a displacement in the vicinity of 32,000 tons. However, their endurance tended to be pretty similar, because they were larger and heavier, and because at a point you start burning more fuel just to carry around the rest of your fuel. (The tyranny of the steam turbine equation?)

But let's you could strip the Omaha down to its essentials (say half its normal weight, ~4,000 tons) and stick it in a giant Maryland-shaped fuel tank with negligible weight and 28,000 tons of fuel. That would be 14 times the fuel the Omaha normally carries, but it's pushing four times the weight, so let's say it's triple the operational range. That's 27,000 nautical miles, or only 112 days at cruising speed. (About a year if they only cruise during the day shift.) And this is ignoring the inefficiencies that would inevitably crop up with a bigger, more drag-inducing hull, more complex mechanisms, and whatnot.

So this explains the why of your question: ships just can't make this kind of expedition. Even a sailing ship that's powered by wind and fed on fish needs periodic stops to repair, to say nothing of the psychological needs of the crew. Going across a huge ocean to a specific point is relatively easy, but going back and forth, back and forth charting it takes a very long time, and there's vanishingly low odds of it being worth your while.

Answer 4

Here is my basic idea: Chinampa design that grows oysters in it's fields. https://en.m.wikipedia.org/wiki/Chinampa

A Chinampa is a Aztec floating garden used for farmland. This would have to be different due to the way oysters are grown. Now what I was thinking is the shop would have large cut outs that have the simple reed beds that hold the oysters which (once you put soul into it from the island would act like a artificial oyster bed). You would also have to boil sea water to keep the water brackish (salty but not ocean levels), but you need the salt as a preservative anyways.

Number wise from what I have read on the Wikipedia's oyster farming article (https://en.m.wikipedia.org/wiki/Oyster_farming) it says at one pint 2000 baby oysters per square meter. I personally have no idea of that's more or less then average so for my guesstimation let's go with 1000 oysters per squre meter. You are going to need lots of different batches though so that every year you have enough oysters and then some.

A the average calories in a oyster is 43 for a eastern wild (84 grams). So if you had 30 square meters of oyster beds (4 per year) you should have enough oysters to have around 16 oyster per day (this is the math for the 5 year voyage). Which would mean around 688 calories split between the duo. Now Google tells me that you need around 2,000 for a male to stay "normal" so you would have to supplement the oysters with fish, kelp, and what ever else you find. But if you have decent storage space it should be plausible to have enough food everyday.

Now finally (sorry for taking so long to get to the real answer :p) space. So we already have 30 square meters of oyster beds. Add another 10-15 for the car walks and wals around them. Now you would need storage and slapping quarters (which can be combined) which would probably take up about another 20 due to the amount of storage you need to make up for "bad days" with the fishing.

In the end I propose around (roughly) 65 square meters (around 700 square feet if you round up) which is the size of a apartment/small house. (I'm on mobile so I can't upload a pic easily). Know you could maybe make it smaller but if my plan works and is sound you have a continue good supply and enough back ups to last the 5 years and some extra room for living space.

Answer 5

I suggest that your hero have a fleet or squadron of ships, common in exploring expeditions. When ships need to be repaired, refueled, resupplied, replaced, or change crew members, they can go to a port while the rest of the fleet stays at sea.

Or the whole fleet can go to the port, but your hero stays on one of the ships that anchors in the harbor instead of docking, and he never goes ashore on a boat, thus keeping his vow never to set foot on the continent. Thus he may have to transfer from ship to ship from time to time.

And if they find any good islands, they can use those as bases, getting whatever food, water, fuel, or other supplies they can from those islands. The hero may stay on one of the islands whenever a ship or the whole fleet has to return to the continent.

Thus most crew members may spend only a few months a sea between visits to the continent, but the protagonist can stay afloat for years or decades. Sort of "The Man Without a Continent", so to say.

The boats or ships in the fleet can use sails most of the time and engines only on rare occasions, thus conserving fuel and making it last for years. Many people who live in sail boats and make long voyages or sail around the world use the sails most of the time and the engines rarely.

So the size of the vessels in your fleet can vary from small sailboats with cabins suitable for a couple of people to the largest ships that have ever been propelled by sails. And that includes many large 19th steamships equipped with masts and sails for emergency use.

For example, Great Britain (launched 1843), of 3,764 tons, the prototype for modern ships, had five masts for sails, later reduced to 4 masts, and had her engines taken out in 1882 and became a three masted sailing ship for several voyages.

SS Great Eastern (1858-1890) of 18,915 tons, had six masts for sails.

The Pruessen (1902-1910) (11,150 tons) the only five masted square rigged windjammer.

The Thomas W. Lawson (1902-1907) of 13,860 tons, the only seven masted schooner.

The Club Med 2 (1996) of 14,983 tons, with five masts.

And so on.

https://en.wikipedia.org/wiki/Club_Med_21

See also the list of the longest wooden ships:

https://en.wikipedia.org/wiki/List_of_longest_wooden_ships2

Answer 6

WWWI tech? not a wooden ship: even the best ones you can get your hands on will deteriorate to a critical level during a non-stop voyage on the ocean. You will be needing a steel ship. Food: the ocean is generous enough, far as proteins go, but it won't provide you the vitamins, fibers and carbohydrates coming from fruits and veggies (scurvy, anyone?). You'll be needing greenhouses aboard. Water: You also need a rudimental desalinizer and to collect rainwater. it comes by itself that, with time, your personal hygiene will be based on water only as you can't produce soaps. ENERGY: Wind & Sails, no other options. An equipped steel ship cannot be propelled by oar -unless you want to triple the crew for your slaves and add more sustainment problems, that is. MEMORY: Pen & Paper, far as you have both of those, then it's back to oral tradition. Possibly, the voyage will become a religion for itself, like in "Orphans of the Sky" by Robert Heinlein SEX: Sorry, gus, but unless you are all T-1000s, you'll be needing more than motivation to resist certain...urges. And even a 50% males/50% females crew will show attritions. Not to mention that new mouths to feed (babies!) will further strain the resources. In short, whatever the reason behind this voyage, that closed system that is a ship will end up in a BAD way. That is why sailors came up with the sinister definition of 'long pork' for their peers...