This weekend I had a unique experience, in a course of ** Salvation, survival and Rescue in water ** dictated by the Aragua rescue group, apart from everything it was an OMI course (International Maritime Organization), it is a course that It requires both physical and psychological preparation because its levels of demand are very high.
There I acquired some indispensable knowledge that would be selfish on my part not to share them with my surroundings.
I will "dictate" the theoretical course by this means, but I really encourage everyone to live that experience.
First we must know some concepts or basic terms such as the following:

Survivor:

That survives a dangerous situation.

Survival:

Conservation of life, especially when it is in spite of a difficult situation or after a fact or moment of danger.

Buoyancy:

Ability to float a body.

Salvage:

Action to save from a danger, especially in an accident.

Rescue:

Release a person from a certain situation of danger or that oppresses, overwhelms or bothers.

Okay now knowing this let's go a little deeper

Buoyancy: We already defined that it was buoyancy, now we fly in the types, they are three

Positive buoyancy: positive buoyancy occurs when an object is lighter than the fluid it displaces. The object will float because the pushing force is greater than the weight of the object. A swimmer experiences a large amount of flotation force. Dead Sea of Israel is famous for attracting floating tourists. Salt water is less dense than fresh water and provides a more buoyant force. Flotation and network forces are not the same. the volume of an object and the density determine its buoyancy.
Negative buoyancy: negative buoyancy occurs when an object is more dense than the fluid it displaces. The object will sink because its weight is greater than the floating force. A submarine is designed to operate underwater by storing and releasing water through ballast tanks. If the order is given to descend, the tanks take in water and increase the density of the vessel. Archimedes discovered the king's crown was made of a less buoyant substance than sunken gold coins.
Neutral buoyancy: neutral buoyancy occurs when the weight of an object is equal to that of the fluid it displaces. A diver is trained in techniques to regulate underwater buoyancy. Swimming horizontally and taking deep, long breaths allow the diver to push forward, not up. the buoyancy of control of the fish through an internal swim bladder. Similar to a submarine, the bladder fills with gas as a means of altering buoyancy.
Despite this described there are always cases and exceptions, since a thin person can easily sink and a fat or obese person float with the greatest peace of mind in the world.
(I thought it was negative buoyancy because at first I sank as a block, and that I weigh about 50kg but it was more than all nerves, then calmly floated to the point of impressing the instructors hahaha)

Survival at sea

Waiting for a rescue aboard a raft or afloat usually triggers fear, impotence, guilt, denial of evidence or irritation. But none of these feelings provides solutions.
Check the survival material included in the raft and remember that you can survive for more than 100 days adrift. The worst enemies of the castaway are hypothermia, dehydration, fatigue and sleep.

Mainly avoid drinking water and eating the first 24 hours for better distribution and performance.

Enemies of survival in water: Humans can live 3 weeks without food and 3 days without water. Depending on the weather conditions, people who have been without water for more than two weeks have been registered.

Dehydration:

The lack of water causes dehydration, causing lethargy, headaches, dizziness, confusion and even death if the percentage of water lost is high (+ 15%).
-Clinical chart
Symptoms of dehydration can include headaches, similar to those experienced during a hangover, a sudden episode of visual snow, decreased blood pressure, dizziness and fainting when standing due to orthostatic hypotension. If treatment is not given, delusions, unconsciousness and, in extreme cases, death may occur.

The symptoms of dehydration are noticeable after having lost 3% of the volume of water. Initially thirst and discomfort appear, possibly accompanied by loss of appetite and dry skin. Athletes can suffer a loss that increases by 30 percent, flushing appears, resistance is lost, heart rate increases, body temperature increases, and fatigue quickly appears.
-Symptom

Intense thirst
Hunger
Abdominal, spinal, headache or extremity pain
Nausea
Slow body movements
Dream
Dizziness
Fatigue
Breathing through the mouth

-Dehydration rates

The symptoms of mild dehydration include thirst, decreased volume of urine, which becomes darker than normal; fatigue for no apparent reason, shortage of tears when crying, headache, dry mouth and vertigo when standing up (orthostatic hypotension).
In moderate dehydration, urine may not be produced. Other symptoms of this state include lethargy and drowsiness, attacks; in babies there is a collapse of the fontanels, fading and sunken eyes.
Symptoms become increasingly severe with increased water loss. The heart rate and respiratory rate begin to increase to compensate for the decrease in blood plasma volume and blood pressure. In turn, the body temperature may increase due to a decrease in sweating. When losing around 5 or 6 percent of water, the individual is drowsy, may have headaches, nausea and tingling in some member. If 10 to 15 percent of the body's water is lost, the muscles become spastic, the skin dries and wrinkles, the vision becomes cloudy, the volume of urine is greatly reduced and urination can be painful, and He starts to rave. More than 15 percent loss is usually fatal. Sometimes the appearance of all these events may take more than a day.
Dehydration death can occur within 3 to 5 days.

Hypothermia:

Decrease in body temperature below normal.
The signs and symptoms of hypothermia include the following:

Chills
Babble or murmur
Slow and shallow breathing
Weak pulse
Clumsiness or lack of coordination
Sleepiness or very little energy
Confusion or memory loss
Loss of consciousness
Cold and bright red skin (in babies)

A person with hypothermia usually does not realize their condition because the symptoms occur gradually. In addition, the confusion of thought related to hypothermia prevents one from being aware of what is happening to them. The confusion of thought can also lead to risky behavior.

Safety in cold water
It is not necessary that the water is frozen to cause hypothermia. Any water that is colder than the body can cause heat loss. The following tips can increase the survival time if you accidentally fall into cold water:

Wear life jacket. If you plan to sail, use a life jacket. The life jacket can help you stay alive longer in cold water because it allows you to float without spending energy, in addition to providing some insulation. Keep a whistle attached to the life jacket to send help signals.
Get out of the water if possible. Get out of the water as much as possible: you can climb on an overturned boat or grab an object that floats.
Do not try to swim, unless you are about to be saved. Unless there is a boat, a person or a lifejacket nearby, do not move. If you swim, you are going to spend energy and you will not be alive for so long.
Position your body in a way that minimizes heat loss. Adopt the position where the body loses less heat, which will help keep you warm while help arrives. Embrace the knees to your chest to protect the trunk. If you are wearing a life jacket that makes your face face down in this position, put your legs together, stick your arms at your sides and keep your head back.
Curl up with other people. If you fell in cold water with other people, gather in a circle looking at each other to keep warm.
Do not take off your clothes. While you're in the water, do not take off your clothes because it helps isolate you from the water. Close all the buckles, buttons and closures that your clothes have. If you can, protect your head. Take off your clothes only once you are safe and have left the water, and take the necessary measures to dry and warm yourself.

Personally, being thirsty and just having salt water around you is exasperating; To remain hours in the water feeling the cold currents is a stressful experience, if in my case I knew that everything was controlled in case of hypothermia I was up to the expectations and nervous I do not imagine a 100% real situation where you do not know when they will come for you.

Following the topic of survival I was investigating to go deeper into the subject and I found a very good information, which is just what I practice.

The following information is in Spanish, but you can download the pdf in the link below and translate the document in Google Translate.

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This information was obtained in the following link https://esupervivencia.files.wordpress.com/2012/05/rescate-y-supervivencia-en-agua.pdf
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I hope you like the info and it is useful for you

Rescue, survival and Rescue in water