by Lee D. Zlotoff

[MakeShift was a column and competition, by MacGyver creator Lee Zlotoff, that ran in Make: magazine for its first five years. This challenge appeared in Make: Volume 08, 2007. Read past installments of MakeShift here.]

There are few fears more primal than being cast away on a deserted island in the middle of who-knows-where. Maybe it’s a throwback to our eviction from the Garden, or the nagging realization that Earth itself is just such an island in the endless ocean of space. Whatever the reason, it has been and will remain a mainstay of the collective imagination.

The Scenario:

You are on a small sailboat in the South Pacific when a freak wave of Biblical proportions swallows your craft. You awake to find yourself on the rocky, sandy beach of — what else? — a tiny deserted tropical island. As the fierce equatorial sun beats down on you, you realize that the boat is gone, but a large section of the white, waterproof nylon sail has washed up on the beach.

Relieved that you are alive and have sustained no major injuries, you quickly scout out the island. There is a cave for shelter, an abundance of vines and vegetation, but no trees to speak of. You see enough sea birds and marine life to provide a subsistence diet, but there is no source of fresh water! And the rainy season is still months away.

The Challenge:

Come up with a reliable way to produce potable water until you are rescued — or the meaning of life is revealed to you, and being rescued no longer matters.

Your Supply List:

You have only the nylon sailcloth and what you were wearing when you washed ashore: a dark, waterproof windbreaker; a T-shirt; and shorts, in which you find your Swiss Army knife (or Leatherman tool) and a pack of waterproof matches. If it provides additional motivation, feel free to be cast away with the fantasy celebrity of your choice — but this person is still counting on you to provide drinkable water. And if you’re looking for extra points here, forget the pack of matches.

Good luck, and rest assured that we’re all out there looking for you.

Analysis, Commentary, and Winners

Kudos, castaways! Apparently this was a relatively straightforward MakeShift challenge, and virtually all of you who responded saw pretty much to the heart of the solution.

Humans can live for an extended period of time without solid food, but fresh uncontaminated water is another thing entirely. As a species composed of more than 80% water, with our critical body thermostat relying on a consistent method of (re)hydration for temperature regulation, we know that fresh water suitable for drinking is our top priority. And the logical solution in this situation was to construct a solar still that utilized desalination of salt water — or the moisture in vegetation — through evaporation.

It was apparent that the dark-colored windbreaker would heat up when exposed to the sun, thereby evaporating water relatively quickly from its surface, and the white nylon sailcloth would stay much cooler and could act as a condensation collector when the windbreaker gave up its heated contents. Some entrants also recognized that a closed system, one that was protected from the wind, would collect more condensed fresh water than if it were open to the wind, since the wind passing between the windbreaker evaporator and the sailcloth condenser would take water vapor with it. All things being equal, a larger solar still would make more fresh water from salt water in the same amount of time than a small one would, so more points were given for size and wind protection.

A few of you opted to use the matches to build a fire-heated still. While this might be theoretically feasible, given the nature and limits of the sailcloth and windbreaker this would be a very tricky operation requiring considerable time and care that might be better spent gathering food. And how long such a system could function before the materials involved were compromised by the fire was also a factor weighing against it.

One individual took an entirely different approach and designed a charcoal filtration system based on the principle of osmosis. The scientific principles involved were sound but the reverse osmosis systems that are used today in water purification plants are much more complex than the simplified design presented in this entry. For my money I would rather rely on the simplicity of an evaporation-based water desalination system. Still, it was a uniquely creative approach to the problem and, as such, worthy of attention.

You were also offered the option of selecting the celebrity of your choice to share this adventure if you so desired. On the face of it, this option seemed like a humorous aside and most of you either ignored it or rejected it on the basis that another person would simply be another mouth to feed and water. One entrant, perhaps deranged by the desperate situation, contemplated killing their celebrity partner for food, fluids, and the nifty cup that could be made from their skull. Let’s hope none of us ever gets stranded with him! Most of you who opted for a celeb, however, followed your fantasies to the likes of Angelina Jolie and Scarlett Johansson. Not bad choices really, if you consider that the rescue efforts to find them might be substantially more robust than those mounted for us mere mortals. But there was a deeper point to the celebrity option beyond simple amusement. While it’s true two people require more food and water, your chances for survival are more than doubled by having another person along, be it for trapping and collecting food, constructing shelter, or general morale and sanity issues. We humans are ultimately social creatures and, particularly in dire circumstances, it is partnership, collaboration, and the combined efforts of bodies and wills that frequently make the difference between survival and extinction. The specific challenge here was to produce fresh water, but the larger challenge was to survive. If we’re to do that, either as individuals or as a species, we’d do well to keep an eye on the big picture and make the most of all the options we have.

So, congrats to all of you for your excellent survival skills and to the two winners listed below. And a special Honorable Mention Award to the third-graders in the After School Science Club at Chapman Hill Elementary School in Salem, Oregon. Teacher Maureen Foelkl and her students Savannah Brown, Cory Francis, Marisa Chen, and Emily Farnell, took on this challenge as a science project and submitted an elaborate and impressive set of materials which contained an imaginative solution. MacGyver would be proud of you all!

The Winners:

The winners of the MakeShift Volume 08 Challenge are:

MakeShift Master — Most Plausible: John Hannan
MakeShift Master — Most Creative: Ben Bond
Honorable Mention — Chapman Hill Elementary After School Science Club in Salem, OR