What do we know about buoyancy? In general and buoyancy for freediving? You normally learn it on your Freediving course, but lets refresh it here.
Google tells us that buoyancy is the upward force applied by a fluid on an object when the object is put in or submerged in the fluid. In a more simple way for freedivers, it means “sink or float or stay on the same depth.”
Why does it have any meaning for us as freedivers? If you are not properly buoyant, it will cost you much more energy to cover the same distance. But as freedivers, we want to save energy as much as possible, not to spend it.
There are 3 types of buoyancy: positive, neutral and negative.
If we refer to Google again, we can find out that positive buoyancy occurs when an object is lighter than the fluid it displaces. The object will float because the buoyant force is greater than the object’s weight. Neutral buoyancy occurs when an object’s weight is equal to the fluid it displaces. Negative buoyancy occurs when an object is heavier than the fluid it displaces. The object will sink because its weight is greater than the buoyant force.
In more simple words, if the freediver is positively buoyant at a certain depth – he floats up without any effort. If the freediver is neutrally buoyant – he stays on the same depth and doesn’t move up or down at all. I believe we can compare it to zero gravity feeling. I have never been to space yet, but I guess neutral buoyancy is what we might feel while wondering in the universe. Negative buoyancy is when the freediver just keeps falling down if he relaxes and doesn’t move. This “phenomena” is called freefall and for many freedivers, this is the best and most favorite part of dive.
Buoyancy depends on different factors – personal and external.
A personal factor, which influences the buoyancy, is body composition. Different body tissues have different density – bones and muscles are heavier than fat. Skinny people are usually less buoyant then people who have some body fat.
When we are talking about external factors influencing the buoyancy, first we need to think about the environment. In saltwater freediver more buoyant than in the freshwater due to different water density. So don’t forget to adjust your weights correspondingly, if you change the diving conditions. Otherwise, duck dives in the sea will be a real challenge, if you take the same amount of weights, which you take normally in the lake.
The second important external factor is a wetsuit. Wetsuit does affect buoyancy. The thicker is a wetsuit, the more buoyant it is. And the new wetsuit is more buoyant than the old one. Which means, if you are diving for 2 years in the same wetsuit you may need fewer weights after a certain period of time, then you used when your outfit was a brand new one. Just opposite – if you get yourself a new wetsuit – don’t forget that you may need some extra weights.
What you can do if you are too positively buoyant? You can add weights on your weight belt or neck weight. It is more difficult to adjust the buoyancy if the freediver is “too heavy” in the water. The easiest way is a wetsuit – if you put it on – it will make you more buoyant. But, if for some reason you cannot wear a thicker wetsuit – maybe it would be too hot in it, and then nothing could be done. At least at the moment, freediving gear manufacturers cannot solve the problem of negatively buoyant freedivers. Who knows, maybe soon someone will create rash guards with tiny balloons all around? We’ll see 🙂
And now, let’s discuss how we can check if we have proper buoyancy for open water trainings.
First of all, the freediver needs to be positive buoyant on a surface – when he lies down on a surface he is not sinking. The reason for it – you want to be able to rest before and after the dive – before the dive, you want to relax and take time to prepare, and after the dive, you might be a bit tired and want to recover. If you need to kick to stay on the surface – it is not the most relaxing, right?
Except being positive buoyant on a surface you need to be positive buoyant even after passive exhale. What does it mean “passive exhale”? You do full inhale and then you exhale without any force, passively release a little bit of air. After this manipulation you still need to float on a surface – may be a few centimeters below the surface, but definitely not sinking (even slowly) down.
If the worst-case scenario happens and the freediver loses consciousness on the way up, he will still stay positively buoyant on ascending and the whole rescue procedure will be much easier to do. Because when the freediver loses consciousness, the diaphragm relaxes and goes to the neutral position, which results in a little exhale. So when we do a buoyancy check with a passive exhale on a surface, this is a kind of imitation of air release in case of a blackout.
Besides, the freediver should be also positively buoyant the last couple of meters of ascending. Because on the last few meters of ascend freediver passes the riskiest depth, so it would be more reasonable to save little energy and not to kick hard. In this situation, the freediver can slightly relax and save some energy (read oxygen) on the last 5-10 meters due to positive buoyancy, which helps to prevent shallow water blackout.
Neutral buoyancy should be somewhere around 10 meters. At this depth, you don’t sink or float up. How you can check it? You dive to 10 meters. You slightly hold the line – make some kind of loop with your fingers around the line, so you don’t actually touch the line. And you will see if you go down or up. Ideally, you should stay on the same level – this means you have neutral buoyancy at this depth.
The depth of neutral buoyancy depends on how deep the freediver is going to dive and for experienced freedivers depth of neutral buoyancy might be deeper. But if you are a beginner or intermediate level freediver, you need to be neutrally buoyant at 8-10 meters. There is a one really cool warm-up exercise which our students find enjoyable. If you feel comfortable at 10 meters, try to hang there for a while. If you close your eyes, you can imagine yourself an astronaut in the open space out of gravity. This exercise we call hangs. But don’t hang too long – always remember you still have 10 meters to go up to the surface.
And when the freediver passes neutral buoyancy he gets into the impact of negative buoyancy. At the beginning of 12-13 meters, you don’t feel it much, because it is still very light. If you relax for freefall at this depth, you will fall super slow and just waste your oxygen-treasured time. So I wouldn’t recommend you to start freefall shallower than 15 meters.
After your turn on the planned depth, you need to do the way up which is just opposite to the efforts on the way down – first, you need to kick really good and strong to struggle with negative buoyancy. After you pass neutral buoyancy, you get into the positive buoyancy world and can relax a bit. Last 5-6 meters you may just float up fully relaxed without moving or glide a lot between kicks or between pulls, depending on your freediving technique.
To make a conclusion I would like to underline once again the key points of this article – when you check the buoyancy – you check it first on a surface. Even after passive exhale you should be positively buoyant. If you start sinking after passive exhales – remove the weights. Check if you are neutrally buoyant at 8-10 meters. If you sink – remove some weights from your belt.
And the main things – don’t forget to enjoy your freefall and your hangs in space.
There are many debates whether CO2 tables are useful or useless for Freedivers. And in a reality, as always, truth is somewhere in the middle.
We practicing CO2 tables, classical and modified on our Advanced Freediver and following courses.
STA breath hold
First, what is a STA CO2 table.
Take 50% from your current maximum STA and repeat it 6-8 times, every time decreasing rest time. If you current max, let’s say 2 minutes, this is how classical CO2 table would look like for you
Before you start doing this type of training or critique it, lets ask the main question – what is your goal in this kind of training? Have a longer breath hold?
Now let’s have a look what happens during this table.
First, a Freediver who do this table, practicing relaxation breathing. Seven times from 2.00 to 0.30 practicing important skill. Calm down your mind and relax your muscles. Don’t underestimate this skill
Next the Freediver trains how stay relax while holding your breath. And this is obviously crucial skill for all levels and especially for beginners. Don’t try to be tough and “handle” contractions, learn how to hold your breath longer without them!
Probably first 4-5 attempts going to be quite easy and you won’t experience any urge to breath symptoms – beautiful, coming out from your comfort zone in not your priority at this moment.
And might be on the last 1-2 the Freediver going to have 1 or 2 contractions. Don’t hold your breath longer. In addition to previous goals, for these two attempts we also train how to stay relax during these first couple of contractions
If you don’t have any – on the next training increase each breath holds by 5 seconds
My conclusion – if you are beginner or intermediate Freediver and trying to build a foundation – this classical STA CO2 table is a legit way of training!
But then why a lot of experienced Freedivers critique it? Because it is a waste of training time for THEM! They already mastered how to do relaxation breathing or how to stay relaxed and not to panic during first contractions. They passed this step. Now they have different goals
And yes, classical CO2 table is not the most effective way to train tolerance to a high level of CO2. But if your STA is less then 4 minutes, do you really need to train it? Or your priority to learn basics, which is relaxation, not suffering?
Don’t blindly copy the way how champions are train, when you a beginner!
It wouldn’t be a surprise if I say that it is not that many available Freediving books around. The last one which I read was “Oxygen” by William Trubridge. And I am also in the middle of “Manual of Freediving” by Umberto Pelizzari.
So, it was a pleasant surprise when the book “Longer and Deeper” by Jaap Verbaas was published a couple of months ago.
I don’t know the author personally, but I read a couple of his articles on the website Freedive Wire and also saw a couple of thoughtful comments here and there on different social media.
So, I was pretty excited to get his book. Is it worth to get it?
My opinion – 300% yes. First of all, it is not a “beginner level” manual, where an author explaining MDR or hyperventilation and you are skipping it because there is nothing new there. It is also not complicated medical research where you should Google every second word to understand what the article is about. It is somewhere in the middle.
But what is it exactly about? The book is mostly about how and why to train “dry”. There are exercises with explanations on how to do them and what exactly you will get from it.
I am not telling that these exercises are unique and you couldn’t find them somewhere else. But I was hooked by simple explanations about how exactly they work as a cross training for a Freediver. I haven’t met such detailed explanations before.
For whom this book will be useful? If you are a highly experienced Freediver with an academic background in the human physiology – then probably you will not find anything new. For anyone else – give it a try. Especially if you are not simply trying to increase your PB’s, but also want to understand deeply processes in the body during apnea training.
For example for me, none of the exercises was new (ok, I never tried apnea squads), but an explanation of how it works boosts my interest to understand more about certain parts of human physiology. So, because of it, I spent the last month trying deeply understanding different processes in a human body during apnea.
Overall this book is definitely in the TOP list of Freediving books for me at the moment and I definitely recommend reading it. And also I hope the author is not going to stop and will continue his researches and we can expect the second edition in the near future!
First of all, lung overexpansion (LO) injury is very rarely in Freediving. So, don’t be scared. But since it can be a serious trauma better to have a solid understanding of what it is and how to avoid it.
First, let’s have a talk about the structure of the lungs.
Our lungs are sponge-like air-filled organs that transfer air molecules to and from blood cells. The trachea (windpipe) conducts inhaled air into the lungs through bronchi, which then dived into smaller branches (bronchioles), finally becoming microscopic.
The bronchioles eventually end in clusters of very small air sacs called alveoli. In the alveoli, O2 from the air is absorbed into the blood and CO2 (a waste product of metabolism) moves from the blood to the alveoli (and eventually exhaled). This process in the alveoli calls gas exchange.
Lungs are major airspace in our body. We have actually two lungs – a right and left lungs. They are situated within the thoracic cavity of the chest. The right lung is bigger than the left, which shares space in the chest with the heart.
Lungs are delicate tissues, and can easily be ruptured. If the air flow inside our lungs becomes restricted as you ascend, the expanding air can rapture the delicate alveoli inside the lungs. This can happen without any warning sensations (since the lungs do not sense pain). Chest congestion, scar tissue, lung disease, and damage from smoking can also create air flow restriction and contribute to LO.
When you do a scuba course, your instructor going to repeat many times that the main rule of Scuba Diving – never to hold your breath. Why?
When you do scuba diving you breathe compressed air from scuba tanks and your lungs have the same volume at any given depth. This is why if you are even 10 meters deep and make a rapid ascent with breath hold (due to a panic let’s say) your lungs will expand twice from the normal size! Lung tissue can stretch out a little bit, but not twice from its normal size. Which is easy can bring a scuba diver to the risk of lungs barotrauma.
Lungs barotrauma (LB) can be in a few basic forms
Arterial gas embolism – gas from the lungs escapes into the bloodstream (which can form bubbles and block blood circulation)
Pneumothorax – air enters the space between the lungs, expands and cause lungs to collapse
Mediastinal emphysema – air enters the space between the chest and the lungs, expands and put the pressure on the lung, heart, or blood vessels.
Subcutaneous emphysema – air escapes from the lungs and travels underneath of the skin (most often around the neck), which can result in voice changing, difficulties swallowing
Common symptoms of LB are
Paralyze, especially on one side of the body
Dizziness and confusion
Coughing up blood
Loss of vision
Change in voice
Heavy chest pain and difficulties in breathing
Is lung overexpansion can be a problem for Freedivers? Normally it is not. When you freedive, lungs compressed on your way down and re-expand on your way up to the original volume. So, there is no overexpansion.
But let’s have a look at two situations which can have a potential risk of lungs overexpansion injury
BREATHING FROM SCUBA TANK UNDERWATER. Imagine, a Freediver makes a dive to 10 meters. His lungs compressed at this depth almost twice. When he ascends, lungs come back to their normal shape. But what happened if Freediver takes a breath from scuba tank underwater and then ascent? After inhale from scuba tank lungs will expand to its normal size (sea level), but then, on the way up the lungs will expand twice. What about exhaling on the way up? It will defiantly reduce the risk, but not illuminate it (you also have to keep the ascend speed as slow as you can). But to remove the risk – DON’T TAKE AIR FROM SCUBA DIVER UNDERWATER!
By doing packing Freediver will over expand the lungs on the surface (lungs volume is going to be higher than Total Lungs Capacity). Then Freediver dive to the planned depth. During the dive he is going to have MDR (blood shift in particular) which moves a certain amount of blood into the lungs (causing blood vessels around alveoli to expand in size), preventing from crushing. On the way up air starts to expand, and blood vessels still bigger in size. This theoretically can increase the risk of lung overexpansion. The risk is not huge, but do exist. To minimize it, Freedivers who are packing exhale before they reach the surface (which also decrease the risk of BO). So, before you start practicing packing, please ask your self – DO YOU REALLY NEED TO DO IT? Please, keep in mind that packing is a highly advanced technique and should be practiced only by experienced athletes. Are you high experienced Freediver?
Treating lung overexpansion injury.
Symptoms of LO occur immediately and can include difficulty breathing, chest pain, crackling under the skin, unconsciousness or death. First aid must begin immediately while transportation to a medical facility is arranged. 100% O2 should be provided as soon as possible and CPR started if necessary. Ask yourself, do you have CPR skills?
The victim will need treatment in a hyperbaric (pressurized) chamber as soon as possible to shrink the air bubbles, and then slowly decompressed to allow the air to pass out of the body before it expands and interferes with respiration and circulation.
Suspected tension pneumothorax is treated with needle decompression followed by tube thoracostomy (at the hospital of course). If a smaller pneumothorax is present and there is no sign of hemodynamic or respiratory instability, the pneumothorax may resolve when high-flow 100% O2 is given for 24-48 hrs. If this treatment is ineffective or if a large pneumothorax is present, tube thoracostomy is done.
Computed tomography of the chest is recommending in any case of suspected pulmonary barotrauma in order predicting future fitness to dive
Freediving, as a recreational water-based activity (as well as a sport), getting more and more popular. But still, it is far away from other water activities, like for example scuba diving.
There are a lot of myths around Freediving, which stopping people to try it. Or at least confusing.
Let’s try to find out which one is true and which one is not. So, let’s start!
Freedivers can come much closer to the marine life. NOT TRUE. Well, actually it depends. If you compare an experienced Freediver and a beginner level Scuba Diver, then it is true 100%. But if we compare both an experience Scuba Diver and a Freediver, then it is not that simple. As a former scuba instructor, I had a few thousands of dives and I can say that majority of the marine life can come very close to you (reef fish, turtles, stingrays, sharks etc). Less than a half meter. Some people are saying that fish afraid of the bubbles. But why should they be? Fish are afraid of their natural predators and they don’t make bubbles. Fish afraid if you make too much movement and if you are rapidly closing the distance. However, I am willing to accept that some marine life can come close to a Freediver (at least I was told so by other Freedivers).
Freediving is more environments friendly. TRUE. Freediving boat is usually much smaller and requires a smaller engine. And they don’t have compressors. It reduces air and water pollution (as well as noise pollution). All of this makes a difference on our impact on Nature. Also, Freedivers are usually not that close to the corals (especially beginner level), so, fewer chances to damage fragile corals. We are also diving on the reefs less often (mainly we are diving just in the blue).
Freedivers have less equipment. ALMOST TRUE. If you compare Freediving vs Scuba Diving – you will probably think – oh, this is 100% true, but it is not that simple again. If we are talking about starting – then for sure it is true! As soon as you have a mask, you can be a Freediver 😉 For scuba, even for absolute beginner level, there is a standard set – BCD, regulator, fins, scuba tank etc. Coming back to Freediving, like I said, in the beginning, you can just invest in the mask and snorkel. But then it will probably be more equipment – weight belt, neck weight, wetsuit, nose clip, safety lanyard, goggles for the swimming pool, float and rope if you want to train with your buddy independently, etc.
Freedivers are leading a healthier lifestyle. TRUE. Some people like to call Scuba Diving sport, which always confuses me. Obviously, it is not. But freediving is. Even if you are not very serious about results. Freediving training combines correct breathing, different relaxation techniques, different physical exercises (in open water, pool, gym etc), as well as mental training. So, yes, if you like to be connected with Nature and stay healthy – Freediving should be your choice.
Freediving is more dangerous. ABSOLUTELY NOT TRUE. Let’s make a line between Freedivers who are properly educated and follow safety rules and someone who has no idea about basic safety rules and just decided that he/she needs to dive deeper or hold the breath longer. Among the first groups, some problems occur, but they are not fatal. The second group is just playing Russian roulette. But the same is true for any other activity in our life – you have to follow safety rules. Even for walking. Disagree? Try to walk across a high way! When someone tells that Freedivers are dying regularly, I am always asking where this information is coming from. And there is no answer. Simple because it is not true. So, the bottom line here – follow safety rules and Freediving would be the safest water based activity!
Freediving is a more natural way to be underwater. Well, of course, it is TRUE. We don’t create with the scuba tanks on our back. But we have reflexes which help us to stay underwater longer and dive deeper. Holding the breath for a certain time is natural for us, as well to the other marine mammals.
So, what would be your choice? Ideally, try both freediving and scuba diving! In my opinion, if you want to explore reef up to 15 meters deep – Freediving is a much better choice. But if you are planning to explore a dive site 25-30 meter deep, then it is easy to do with a scuba tank. If you are interested in underwater photography or videography, then again, having scuba tanks make your life easier. On the other hand, if you want to enjoy to be underwater and also combine it with a healthy lifestyle – Freediving is a better choice.
If you are interested in proper Freediving education click HERE 😉
What do you think about it? Stop reading for a second and let me know your opinion in the comments section at the end of this article!
Ok, let’s start with it – any activity is potentially dangerous. And I am not even talking about such activities as a base jumping or rock climbing. Walking on the busy street can be extremely dangerous, right?
However, if you follow the rules of this particular activity – risks can be dramatically minimized (don’t walk on a highway for example). And Freediving is not an exception. Follow simple safety rules and Freediving would be the safest water based activity!
But I would lie to you by saying that there are no risks in Freediving. Are they big? Let’s have a look.
It is going to be two parts about most common problems in Freediving.
First one about – LMC/BO/SWB
And second is going to be about lung squeeze, DCS/lung overexpansion/gas narcosis
Before we start – it is very unlikely that you are going to experience it on your Freediving course (especially on the first level – chances close to zero). But with the experience, you are going to be not that much distracted with a high level of CO2 (you still have contractions, but you are going to be more ok with them) and able to hold your breath longer and longer. And longer your breath hold is, less O2 it is going to be at the end of it. And less O2 you have more likely problems can happen.
Let’s say a Freediver decide to do his PB (personal best attempt). He is relaxed and enjoys his breath hold. At some point, contractions (involuntary movement of respiration muscles) will start. But he is still relaxed. He has them before and he is not freaked out, everything is under control. Contractions become harder and harder, but he is still holding his breath. At some moment, contractions became unbearable and Freediver comes up. But because the level of O2 reached the critical level, there is a chance of LMC (loss of motor control). What happens with this Freediver if he has an LMC?
He is still conscious; the heart is working, blood still circulating through the body. But the partial pressure of O2 is too low for normal functioning. He is not fainting, but close to it. Signs can be small (blue lips, light uncontrolled eyes or head movement), or big (body shaking and losing coordination). What happens when a freediver lose coordination while he is in the pool? Big problem…
And this is why your buddy is very important! Safety buddy is going to grab the Freediver, provide support, remove a mask from the face (or nose clip) and encourage him to breathe!
HOW TO AVOID LMC?
No hyperventilation before any breath hold
Don’t push too much (be moderate with your progress and don’t do big jumps in it)
Secure support (float, pool’s edge, your buddy arm) after surfacing
Proper recover breathing after stop holding.
Don’t do PB’s if you are dehydrated, too tired, you haven’t slept well, it is your second training per day etc
AND NEVER FREEDIVE ALONE!
HOW TO DEAL WITH LMC?
Support your buddy, making sure airways about the surface
Remove mask/nose clip
Encourage to do recovery breathing
Be ready to deal with BO
If you have an LMC, take it as a lesson, stop training for at least a day, analyze why it happened and don’t repeat the same mistake ;-)
What is BO? In Freediving we call it a situation when Freediver lost his conscious due to hypoxia (insufficient supply of O2) during the long breath hold. There is a difference between hypoxia and anoxia – complete deprivation of O2 supply. Why it is important to understand this difference?
Anoxia is extremely dangerous because some of our tissues could not survive without O2 supply even a couple of minutes (brain as an example). During hypoxia there is still available O2, but not enough for normal body function. And the protective mechanism launched – Freediver experience blackout.
HOW TO AVOID BO?
Don’t do hyperventilation
Do recovery breathing after any breath hold
Avoid pushing too much your limits (especially if you are a beginner)
Don’t depend on the watch, if you feel that you need to stop – stop!
Have enough time to recover between Freediving sessions
Don’t train when you dehydrated
AND NEVER FREEDIVE ALONE!
HOW TO DEAL WITH BO?
Learn rescue skills under professional supervision
Practice these skills
If your buddy has a BO – don’t panic, you can easily recover him
If you have a BO – stop your training for today
If there is a chance that you inhale water – look for a medical checkup
As you know, BO happens when there is not enough O2 for normal buddy’s function (when a partial pressure of O2 below a certain level).
When we are diving, pressure changes very fast, compared to the surface. When we are only 10 meters deep, pressure increase twice (2 atm), 20 meters – three-time (3 atm) and so on. Same happens with the pressure of any gases in your body, include O2.
Deeper you go higher partial pressure of O2 you have.
But now you turned 😉 And while you are ascending, you are still burning down O2, but now also pressure decreasing. And on the last 10 meters, it is going down twice. And this is where the majority of SWB happens (some of them even on the surface).
It is almost the same recommendations which I wrote about how to avoid BO! let’s repeat
Don’t do hyperventilation
Do recovery breathing after any breath hold
Avoid pushing too much your limits (especially if you are a beginner), in case of SWB – don’t progress with depth too fast
Don’t depend on the watch/depth, if you feel that you need to turn – turn!
Have enough time to recover between Freedives (apply the rule, surface interval 3-4 longer then dive time or more conservative time)
Limit the number of deep dives per session
Don’t train when you dehydrated
AND AGAIN – NEVER FREEDIVE ALONE!
Rescue skills in open water
What to do if your buddy has SWB
Reach the diver
Bring to the surface
Remove the weight belt if necessary
Blow-tap-talk for 10 seconds
2 rescue breath and ask for help
Start moving the diver to the boat/shore, providing 1 rescue breath every 5 seconds
As we all know Freediving requires less equipment than lets say scuba diving. But still need some. In the beginning of your Freediving journey simple set as Freediving mask, snorkel, and pair of fins more than enough.
But if you really want to bring it to the next level, few extra pieces of equipment will help you with that.
As an example – nose clip. Here is a short version of my review (full version, as usual on my YouTube channel – Crystal Freediving)
Ok, it was a long time ago when I decide that I want to do Freediving blog. But writing in English is difficult. And after finish my first blog I was correcting it again and again until I just deleted it 🙂 Apparently with video it much easy since you posted – IT IS DONE!
That’s why the transition from blog to vlog was logical. And here we go, I am a vlogger on a YouTube! 😉
It is not the first episode, but since now I am going to post here a short version of it here. Hope you, my reader, will enjoy it!
If you are interested and want to see full version, find my channel on YouTube – Crystal Freediving