47 METRI

HOME BACK	47 METRI (2017)	EMM#: 48 Added: 01/12/2017
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	Nessun aiuto sopra, nessuna speranza sotto.

47 METRI Movie

2017

(5,7 out of 10)
Avventura (Horror|Drammatico|Thriller)
1 h 29 min - 89 min
Directed by Johannes Roberts

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	Mandy Moore
	Claire Holt
	Chris Johnson
	Yani Gellman

Plot | Cast | Goofs | Synopsis

Durante un viaggio in Messico, due sorelle, Kate e Lisa, si lasciano convincere da due ragazzi del posto a fare un'immersione all'interno di una gabbia per osservare gli squali. Una volta dentro l'acqua rimangono intrappolate sul fondo dell'oceano a 47 metri. Con una riserva d'aria di 60 minuti nelle acque infestate da squali bianchi, dovranno riuscire a mettersi in salvo. La barca che le aveva portate a largo le abbandona per tornare dopo pochi minuti ad aiutarle. Uno dei ragazzi, Javier, si immerge per aiutarle a riattaccare un cavo alla gabbia, ma viene attaccato da uno squalo e muore. Dopo svariati tentativi e dopo esser riuscite ad attaccare un cavo le due ragazze vengono tirate su fino a 36 metri, ma il cavo si rompe, cadono nuovamente e Lisa rimane con una gamba incastrata sotto la gabbia. Kate, in riserva d'aria, esce dalla gabbia per prendere le bombole lanciatele dai ragazzi dalla barca, ma viene divorata da uno squalo. Lisa si trova in preda alle allucinazioni da azoto ed immagina di arrivare in salvo insieme alla sorella ancora in vita. Quando viene finalmente soccorsa dalla guardia costiera, realizza la triste realtà.

The amount of time a diver can breathe on a tank of compressed air decreases with depth. At 47 meters down, a diver would have limited time as the air they breathe is equalized to the pressure at that depth. Every 10m the volume is divided (10m = 1/2, 20m = 1/3, 30m = 1/4, etc.). So 10m below the surface a diver breathes 2x the volume of air. At 50m each breathe is 6x as dense as the air they breathe at the surface. If the diver's surface air consumption (SAC rate) is 30psi per minute that means they would breathe 150 psi per minute at 50m... which is approximately 20 minutes of air. The most common type/size cylinder in scuba diving is an AL80 / 11L at 3,000PSI / 207 bar). Factors that contribute to gas consumption include physiology, fitness level, and stress/panic (such as that caused by being circled by Great White sharks). Thus one hour is highly exaggerated.US Navy dive tables establish the no decompression limit ("bottom time") for 47 meters (>150 ft) to 5 minutes (not including descent or ascent time). A diver has 20 minutes of bottom time at 100 feet using air (21% oxygen).When using an open circuit breathing apparatus, as in the film, a diver breathes compressed air. Air is 21% oxygen and 79% nitrogen. 100% oxygen can potentially result in oxygen toxicity at depths past 19.8ft / 6m depth.It's also quite possible a diver would experience nitrogen narcosis which is similar to being drunk, and simple tasks can be difficult to achieve. Technical diving generally requires Air / Helium (aka Trimix) when diving below 50 meters / 165 feet in order to reduce nitrogen narcosis. <br>------------------------<br><br>The coast guard divers would have been wearing shark shields knowing there were great whites in the area. None of the divers appeared to be wearing one. <br>------------------------<br><br>At some point, the instructor on the boat tells the divers that he delayed sending more air tanks because that would increase their risk of narcosis. 47 meters have limited effect on divers (a common saying among divers is "40 meters one drink, 50m two drinks") and the risk of "hallucinations" is largely exaggerated in the case of two young women in good health. Besides, delaying the delivery of additional air tanks drastically increases the risk for the divers to die from lack of air, obviously a far worse scenario than narcosis (you should also consider the risk that the fall might have damaged their equipment and caused abnormal air consumption). A normal reaction should therefore have been to send additional tanks as soon as possible, ideally attached to a cable that can lead the divers back to the boat (instead of just dropping the tanks in the water with a flashing light). <br>------------------------<br><br>While they are submerged in the ocean, they communicate to each other by some sort of radio device on the diving mask despite their ears are in permanent contact with the water so they would not be able to hear anything. <br>------------------------<br><br>The speed at which the girls fell in the cage would probably have burst their eardrums. This is because they did not appear to equalize once and it would have been very difficult for them to do so effectively wearing a full face mask. <br>------------------------<br><br>The gauge they use to see their air consumption is electronic. This is for the audience benefit at in reality, the air gauge is not electronic but a small pin on a dial which generally shows from 0 to about 300 bar. <br>------------------------<br><br>One of the characters advises their air is running out because the shark punctured their BCD. Air does not leak from a BCD. <br>------------------------<br><br>The girls were told to do a 5 minute decompression stop at 20 meters. The amount of time underwater and at the depth they were, this would not be sufficient and an additional safety stop would be needed at 5 meters. Instead they were told to then swim directly to the surface.. this would have killed them by getting the Bends. <br>------------------------<br><br>At 47m, without direct light, blood looks green not red as spectrums of light are filtered out by the water. However, There are powerful lights attached to the cage and divers have flashlights, which would negate the effect of depth and explain why the red color is visible (both for blood and for the red patches on dive suits). <br>------------------------<br><br>