Outrageous Experiments

Myth Database – Building a Cardboard Boat

posted: 02/09/17
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Check Out a Clip From the Myth and Scroll Down for the Breakdown
MYTH: It's possible to build a seaworthy boat from cardboard.


In this challenge, the candidates were split into two teams: Red (Brian, Jason, Tracy and Jon) and Blue (Allen, Tamara, Martin and Hackett). Each had to build a boat -- consisting only of cardboard, glue and vanish -- that could house all four team members and finish first in a 500-yard race. To make sure two different designs were tested, one boat would seat team members in a single file, and the other side by side.

As the previous week's MVP,Hackett was able to choose between the two designs; he and his team decided on the single-file option. The Blue Team thus started with a couple of advantages: team member Martin, who has 20 years of experience building sea-kayaks, skiffs and other boats, and the slimline design, which would make their boat faster and their build quicker.

The Red Team decided on a flat-bottom dingy design, and quickly built a small-scale model. But when placed in water with scale weights as a proxy for the four-man crew, the single-ply cardboard saturated in seconds, sinking the boat. They then made a second, quarter-scale model but with a tapered, rowboat design, and sealed it with varnish. That boat quickly capsized and lost any structural integrity. The team thus decided to go back to their original flat-bottom boat design, which would be easier to build, having spent a day on their second boat model.

The Blue Team quickly decided on a design, but decided first to test whether glue could not only hold their boat together, but make it seaworthy. Their initial small-scale boat immediately sank, but they discovered that glue held the cardboard together well; the boat only came apart at the corrugation. The team then made a second replica using glue as an overall sealant; in that small-scale test, the boat was able to float for an hour without any water seeping in.

Moving on to their large-scale build, the Blue Team built a wood form in the shape of their boat into which they lay and glued their cardboard pieces to ensure a straight hull and as much of a solid connection possible with each piece. They also laminated their cardboard in the style of timber, creating a strong beam out of multiple single layers, to be used as cross-supports for the outriggers. Concerned with the boat being watertight, the team mixed leftover cardboard pulp with contact cement to create a durable, watertight composite. To ensure a smooth hull, Hackett wrapped the boat in a thin cardboard skin; installing outriggers to help with stability topped off the build.

Meanwhile, the Red Team's Brian and Jon worked on building their dingy, a square-shaped boat with a little lip in the front, made of the thickest grade cardboard. Jason and Tracy concentrated their time on the propulsion system -- initially a giant paddle-wheel system with pedals, but then, at the last minute, hand paddles, which they didn't have time to properly waterproof.

For the race in the water, Kyle Hill was joined by Mike Kazek, a naval architecture expert and an instructor at California Maritime Academy. Soon after both teams hit the water, two things were clear -- the cardboard boats were waterproof, and the Red Team's paddle-wheel was useless; the wheel was far above the water line. And because the Red Team hadn't waterproofed their paddles, they bent in the water and were very difficult to use.

In the end, the Blue Team finished the race in eight minutes; the Red Team took 14. But both boats were more or less steerable, didn't spring a leak and had payloads 800 pounds.

So the myth that you can build a semi-permanent seaworthy cardboard boat was confirmed.

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