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Special: Jaws Special

  • Punching a shark in the nose or jabbing it in the gills will drive it away: plausible (seemed to respond to the gills)
  • Shark strength feats
    • Ram and pierce boat: confirmed (a 3000 lb great white travelling at 25mph could pierce a boat)
    • Ram and break a shark cage: confirmed
    • Pull down floating barrels: mythbusted
    • Tow a boat: mythbusted
  • A bullet can cause a scuba tank explosion: mythbusted
  • Piano wire can be used as shark fishing wire: mythbusted

This episode was two hours long and involved lots and lots of shark myths, mostly from the movie Jaws.

Related Links: * Shark mini-myth video on Discovery.com * 'Why Shark Week' video on Discovery.com * 'When Pelicans Attack' video on Discovery.com * The 'Shark Lab' at Bimini Biological Field Station describes their involvement in this show * Farallon Islands * Bubble Subs * Photos/Posters of sharks breaching

As the Discovery Channel did not want to be guilty of creating shark hysteria with this episode, there were ads highlighting the fact that sharks are not serious danger to humans. During the show they provided the following statistic:

  • average # of people killed by sharks per year: 15
  • average # of people killed by falling coconuts per year: 150

Shark punching

Myth: Punching a shark in the nose or jabbing it in the gills will drive it away.

In 1963, Rodney Fox attacked by great white shark. He believes he was saved by fighting back.

Human punching test

The plan was to create a Rock 'em Sock 'em Buster, but first they had to take some measurements on human punches. They dressed Jamie up in the "Red Man" cushion suit and had Adam punch him. Using the slow-motion camera they measured the speed of his punch at 20 mph. They then used one of Buster's thighs as a punching bag. Jamie punched it and they measured the deflection at 3 ft.

Using these results they built the Rock 'em Sock 'em punching version of Buster. Kari built made one punching fist and one jabbing fist (fingers extended) and Jamie made the pneumatic punching arms. After getting rid of some valve issues they were able to test Buster with the thigh punching bag and verified that it was similar to human punching force. Adam also dressed up in the red man suit to take some punches for fun.

Kari: "What do you think he'd wear, shorts or a little thong?"

Rock 'em Sock 'em Buster test

They flew to the Bahamas and put Jamie (dressed in chain mail) in a shark cage, holding Buster on the outside of the cage. Buster was stuffed with fish morsels while Adam on the surface operated the valves to get Buster to punch. The water was full of Caribbean reef sharks, which according to the diving expert are responsible for most of the attacks in the Bahamas region

There were quite a few sharks in the waer and Buster punched them up pretty well, even if his aim was pretty bad. The punching did deter the sharks, but it did not drive them away. Buster suffered quite a few bites and was even wrestled away from Jamie.

Rock 'em Sock 'em Jamie test

It's Kari's suggestion that they test with a real human punching as they could not aim Buster very well. They wanted to test two things: * Does punching specifically in the nose and gills work? * Do the sharks get angry from the punching?

Later on Kari starts to get worried about Jamie as the sharks in the water seem more aggressive than the previous sharks.

Kari: "If I was in charge, I wouldn't put him down there"

Kari (to Jamie): "If I see a shark coming up with a beret, I'm gonna be mad at you"

Adam can't wear scuba gear because of problems with his ears but he's able to go down in a bubble sub, which actually looks like quite a lot of fun (I want one).

A chum box was placed in front of Jamie who delivered some light punches to the sharks passing by. The sharks didn't become more aggressive, but they did seem to turn away when they were tapped.

Jamie: "their noses are quite hard" (like bone)

Jamie's observations were that didn't seem to respond that much to punching in the nose, but they did seem to respond to hits on the gills and the softer side.

plausible

Shark strength Myths

The MythBusters did four tests involving shark strength myths:

  • Pulling down three floatation barrels
  • Pulling a boat backwards
  • Smashing a shark cage
  • Smashing a wooden boat

Shark estimation

In order to test these myths they had to estimate the size and strength of great whites. The largest great white known to science was caught off Prince Edward Island and was 21 ft (not weighed). According to Shark Attacks of the 21st Century by Ralph Collier, the largest shark on record was 19 ft long and weighed 4680 lbs. They decided that 17-19ft, 3000 pounds, would be a good 'average' for a mature, female great white.

In order to estimate the speed of a great white, they relied on calculations made from videos of great whites breaching the surface. Based on the video, they believe that great whites are capable of doing 20-25mph.

screenshot screenshot

*you can buy a poster of these awesome Chris Fallows shots

They also needed some rules of thumb for how strong a shark of that size might be. They tried to get some data off the coast of SF by heading out to the Farallon Islands, a well-known shark spot 27 miles off the coast.

photo by dreamsindigital

While Adam curled up in the fetal position due to seasickness, Jamie threw some seal decoys out in the water to see if they could get some sharks to grab them. No sharks were biting, especially not great whites, of which there are only a few hundred along the entire west coast.

Plan B: fly to the Bahamas and test there

With help from the Bimini biological research station, they caught some Caribbean reef sharks (max length of 6 feet, much smaller than great whites). Adam managed not to get seasick this time and they were able to measure a max force of 30 lbs and a steady force of 15 lbs. For towing a boat or submerging the barrels, the steady force measurement is more relevant as they require continious force.

The Caribbean sharks weighed in at 45 lbs, which verified the rule of thumb that the maximum force a shark can exert is it's own weight, and the maximum continous force a shark can exert is 30% of its weight.

Setup

The setup for all four shark strength myths was similar. They used an abandoned dry dock. To simulate the shark they borrowed an MTVL (Mobile Tactical Vehicle Light) from United Defense: 28,000 lbs, has 400hp, and can do 0-20mph in 7 seconds.

Shark Strength: Boat Pull

Myth: could a shark tow a boat like the shark did in the movie Jaws (with water flying everywhere)

They connected the Orca V to the MTVL and accelerate to 25 mph. At 25 mph the MTVL was exerting 4000-8000 lbs of force and a cleat was wrenched out, ending the run (much like in the movie).

The result looked very much like the movie, but the force measurements showed that the shark would have to be able to exert double its weight to replicate the pulling in the movie Jaws (i.e. with the water spraying over the bow/stern).

mythbusted

Barrel pulldown

Myth: can a shark pull three floatation barrels under water?

They managed to procure three of the original barrels from the film from a fan on the Internet.

Adam "The only thing we're told we can't do is burn them, blow them up, or lose them"

Tory: "Has he watched this show?"

Using the MTVL, it took 1200 lbs of foce to submerge the barrels. Their average estimated shark would not be able to hold the barrels under water, though it could temporarily submerge them:

  • 17-19 ft shark, 3000-4000 lbs
  • 30% of its weight on continous pull: 900-1200 lbs of force (ooooo, pretty close)

mythbusted

Shark Strength: Shark cage smashing

Myth: Can a real shark actually destroy a shark cage like the shark did in Jaws.

There is no record of a great white ever destroying a shark cage

Adam recreated the shark cage from the movie while Kari, Grant, and Tory handled the shark ram, the 'Sharammer.' The target was 25 mph, 3000 lbs.

Grant: "3000 pounds at 25mph.. that's gonna be some shark ram"

The sharammer was made by making a foam shark head, making a fiberglass mold of it, then using polyurethane from an art shop to rubberize it. The shark head was attached to a giant metal pipe.

The MTVL towed the sharammer towards the boat, stopping short to allow the sharammer to ram under its own momentum. With water flying everywhere, the sharammer struck the shark cage and took part of the cage with it.

confirmed

Shark strength: Boat (Orca V) smashing

Myth: in Jaws, the shark pierces the side of the Orca and attacks the occupants within.

The setup was similar to the sharammer cage smashing. This time the sharammer pierced the size of the wooden boat and left a hole, though not quite Jaws-sized. The hole was above the waterline so the boat stayed afloat.

confirmed (a 3000 lb great white travelling at 25mph could pierce a boat)

Scuba tank explosion

Myth: In the movie Jaws, Brody fires a bullet at the bottom of a scuba tank in the shark's mouth, causing the scuba tank to explode and kill the shark. The book and movie differ in the ending. In the book by Peter Benchley, the shark is killed by a harpoon. Spielberg changed the ending for a more explosive effect, but Benchley did not think it was believable. Spielberg didn't care, as he felt that he could make the audience believe it.

In 1998, a Florida dive shop technician, Chris Hawkins, lost part of his hand after a tank suddenly ruptured while he was checking its pressure.

They were able to get the actual scuba tank from the movie, which allowed them to verify that it was an aluminum 80 tank (instead of a steel tank). An aluminum 80 tank has 80 cu. feet of air at 3000 psi, which equates to 1.3 million pounds of explosive force.

Setup and Test

Adam and Kari built a foam shark head to hold the scuba tank. A 30-06 rifle was positioned at point-blank range. The entire setup was placed in a shipping container to contain any explosion. The FBI experts also attached C4 to the tank just in case it didn't explode and needed to be disposed of safely.

They tested first with empty tank to see if the bullet could go through bottom of the tank as it did in the movie. Adam didn't think it would go through, despite the fact that the 30-06 pierced two plates of bulletproof glass in a previous mythbusting. The result: it went completely through.

They next tested shooting a full tank through the bottom. The tank flew around the tank like a rocket, reminiscent of CO2 cartridge cars.

They also shot the tank through the side just in case anyone complained and got similar results (note: the bullet didn't make it through both sides of the tank). Their final test wasn't really a test. In order to make thing go 'boom' they decided to blow up the tank with C4. It made a good blast that dented the side of the container and shredded the foam shark head. Half of the tank was blown off, though the rest of it looked pretty solid still.

mythbusted: a bullet could not cause the tank to explode.

Piano wire

Myth: in a deleted scene from Jaws, one of the characters buys #12 piano wire to use as leader on the line for catching great whites.

Adam picks up some of the piano wire and asked the expert what the breaking strength was. The expert estimated it at 300lb of breaking strength (piano wires are tensioned at about 200 lbs). In testing, the wire broke at exactly 300lbs, which isn't close to catching a great white.

mythbusted

Comments

Coincidentally, I just saw a story about an Australian guy who fought off a shark. Says he kicked and punched the shark "I think in the gill."

http://www.smh.com.au/news/national/great-white-hope/2005/09/04/1125772404044.html

definitely don't want to ever have to use this knowledge, but at least I know where to aim my punches now

We talked about the show this morning on the radio-- since the novel JAWS was published on this day in 1974. I saw the episode of Myth Busters last evening.. I thought it was purposely broadcasted in conjunction with the anniversary. Guess not?! Thanks for the refreshers on the show.

Concerning the holding of barrels underwater ... They don't seen to be considering the weight of the shark -- 6000 pounds of shark underwater is still 6000 pounds -- I don't see how a lazy shark of that size couldn't hold down *ten* barrels (only 4,000 pounds) just by relaxing... This is a calculation they had to consider in the Ping Pong Ball/Boat retrieval episode, correct? Am I missing something? Or were they?

You're missing something. :) The shark is neutral buoyancy, so it can't apply it's 6,000 pounds to the task of holding anything down -- it's not as if the shark were hanging in midair from the barrels; it's being held up by the water. Instead, the shark effectively has zero body weight to work with and must use its muscles to counter the barrels.

On the piano wire, it's obvious they did no research on catching sharks with light tackle. By light I mean monofilament in the single digit pounds breaking strength. The idea is to hook the shark (small ones like grey reef sharks) then play it until it tires so the boat can be moved in to either gaff the shark or remove the hook and let it go.

A SCUBA tank could explode by shooting it, IF it's one made from one of the aluminum alloys that never should've been used for a pressurized air tank. Plug scuba tank explosion into any search engine to find which tanks are safe and which should be scrapped. Fortunately, no tanks have been made for several years with the unsafe alloys.

Sharks - unlike most fish - have no flotation bladder, so when they die (or even stop moving), they sink to the bottom, so their weight would pull things down.

The shark in Jaws was 25ft
long, and so presumably weighed 4500 lbs; A&J should have based their calcs on this, but - as usual - they had to find something they could "bust", so they deliberately did a half-assed job on some of the tests.

On shark-punching:

"If a shark attacks, the best strategy is to hit it on the tip of its nose. This usually results in the shark retreating."

George H. Burgess, International Shark Attack File
Florida Museum of Natural History, University of Florida


http://www.flmnh.ufl.edu/fish/sharks/isaf/diveradvice.htm

If I remember correctly, Charles Lindbergh (first guy to fly accross Atlantic) had similar results firing bullets into WWII aircraft oxygen tanks when he was stationed in the South Pacific theater. Since the Standard .30 caliber bullet used at the time was the 30-06, the scuba tank makes sense, however Lindbergh was able to get the tanks to explode when he fired .50 caliber bullets at the tanks. It is known as .50 BMG or 50 Browning Machine Gun

I've been trying to tell my friends that scuba tanks can't explode ever since you did the scuba tank explosion episode. Would a pure oxygen tank explode if shot by a 30-06?

SCUBA tanks made from 6351-T6 aluminum alloy should not be used. There are testing guidelines that are supposed to ensure they're safe but it's taking a risk. The more often they're filled, the more stress is put on the metal and the more likely the tank will burst. That alloy was used in pressure tanks at least into the 1980's, not just on SCUBA tanks but also on all kinds of bottles for breathing gear. It's also been used for CO2 tanks for paintball guns. The much safer type of aluminum alloy is 6061-T6.