SAFETY FOR FREEDIVING OW SESSION

Let me start with a question – WHY do we need to do safety for each other on freediving open water sessions?

Despite it rarely happens, we shouldn’t ignore a small chance of shallow water blackout on ascend. For this reason, the safety diver needs to dive and meet the ascending freediver at approximately one-third of the depth and escort him to the surface.

Freediving Safety

Let’s have a closer look at the most frequent mistakes.

The first “popular” mistake is not to follow the surface interval between the dives. For example, freediver comes up from the deep dive, and instead of taking full recovery as if he gets ready for his next deep-dive, almost immediately he confirms he is ready to do safety.

What is the problem here? – Obviously the freediver hasn’t recovered fully. When the freediver get ready for his own deep dive, he would take long rest after the last dive and never dive just after the recovery breathing. It takes a while to remove extra CO2 from tissues and renew the gas balance in the body. So why would freediver prepare to the deep dive more carefully then to the safety dive? Just perhaps, safety dive to 10-15 meters doesn’t sound like a challenge. And if a safety diver just need to watch and escort the freediver it is not a big deal at all. But imagine the situation when the freediver loses consciousness and the safety diver needs to grab him and bring to the surface and then also do all rescue procedures. You know, all this lifting and supporting unresponsive diver on the surface is a pretty exhausting activity. So make sure you have a rest long enough to be able to perform as safety and rescuer in case you need to. Take your time, no rush in freediving.

Freediving Safety

The second mistake freedivers usually do is connected to equipment.

Before your own dive, you probably leave a snorkel in the float, to avoid dragging. But when you watch your buddy’s dive from the surface, it is more convenient to have snorkel in the mouth. Of course, you hold the line to know when to start the dive, but sometimes it is not enough – your freediver may forget to pull the line or he pulls too weak. So to look down is a good idea because then you can react faster and not miss your freediver. Which makes snorkel a very useful piece of equipment.

The same story is with the fins. If you train without fins, you still need them for safety. Even if your no fins technique is brilliant, lifting a blacked-out freediver to the surface is not a piece of cake. You have to swim really fast, which will be impossible to do without fins. And use proper freediving fins for safety – scuba fins or monofin are unacceptable, you can use them only for your own dives.

The third mistake is to miss the moment when to start the dive.

How do you know when to start your dive as a safety? – When we are talking about a beginner freediver who dives to 15-20-30 meters, the easiest way to check when you need to start the safety dive is do the following: you lie on the surface and hold the line when your freediver reaches the target depth, he grabs the line for a turn and pulls it (which is a part of turning technique). You feel this pull and it means your freediver started the ascend. This is a signal for you to start your dive.

For deep freedivers it’s a bit different story since they know precisely how long the dive lasts and at what exact depth you need to meet them.

          Mistake number four – not to watch freediver till his full recovery.

I guess this is the most ordinary mistake. Freediver comes up and after he just finishes recovery breathing, you stop paying attention to him and do your own staff. It’s a huge mistake. Full recovery is not the same as the end of recovery breathing. Recovery breathing is a certain amount of active inhales and passive exhales and may last only 5-15 seconds. But full recovery takes more time. You cannot be sure your freediver is ok 5 seconds after he breaks the surface and shows Ok. Some freedivers have a habit to show OK as soon as they can. And it could happen that the freediver has LMC even after he did recovery breathing. So if you are not continuing watching freediver carefully for a while, you may miss the moment when he requires some support.

          Let’s finalize and try to set up 4 main rules for safety in the open water:

  1. follow surface interval timing for your safety dives same as for your deep dives
  2. check/put on your gear before you confirm you are available for safety dive
  3. start the safety dive in time
  4. Watch freediver till he fully recovers, not till the end of recovery breathing.

By Svitlana Gaidai

Decompression sickness in Freediving

Is it possible to have DCS for Freediver? Unfortunately yes…But at the same time, it is quite easy to put the risk at the minimum. At our school, we normally discuss in details this topic at PADI Master Freediver course, so here are our thoughts on this subject…

DCIM101GOPROG0063938.JPGIn scuba diving, when you are breathing compressed air underwater, your body is saturated more and more with Nitrogen (79% of the air is Nitrogen). The chain looks like this – you breathe in the compressed air from a scuba tank and now the pressure of N(Nitrogen) in your lungs more than in your blood, so, it going to your blood. And now in your blood pressure of N is higher than in your tissues, so, it is going to your tissues. Until you have an equal pressure of N everywhere (this is what we call saturation). And when you start coming up, opposite happens. Now pressure of N is smaller in your lungs, so the reverse process is happening – from your tissues N going to the blood and then to your lungs and then you exhale it. But it doesn’t happen that quickly. In some tissues, this process is slower than in others.

So, this is why when scuba divers coming up, they need to do it slowly (in this case N slowly coming from your body with every exhale) and they also need to have a long surface interval between dives (to release as much N from their body as possible before the next dive). And why they can spend the only a certain amount of time on certain depth (not to get too much N to their tissues).

dcs2If they violate these rules, they have a very good chance to have DCS! Without making it too complicated, DCS is when molecules of N combined in your blood (or tissues) in the form of a bubble and can cause very serious damage!

But why it can be an issue for Freediver?
Among the first, spearfishers who were shooting fish relatively deep (around 20 meters) noticed that after the long session they have symptoms which are commonly associated with “bends” (another word for DCS). So, imagine you dive to 20 meters. On the surface, you did big inhale and bring this air (and around 79% of it is nitrogen) to 20 meters, where the pressure is 3 times higher. So, the pressure of any gases inside your lungs (we call it partial pressure) going to be also 3 times higher. If the pressure is going to be higher in the lungs, then it will go to your blood and further to your tissues in the attempt to reach equilibrium. When you start your ascend, the reverse process will take place. But not 100% (some of our tissue need time to release N2). Some N2 will still be in your tissues. Very very small amount. Not a dangerous amount. But then you are going to do 50 dives more to this depth. And now you have much more N2 in your blood. And on your next ascent, it can forms bubbles and this is DCS….

There are also some predisposing factors which can increase the risk of DCS. Let’s name a few

  1. Dehydration
  2. Exercises
  3. High level of CO2
  4. Cold
  5. Not enough surface time

As you can see, spearfisher who is doing a long session with relatively deep dives and DCIM101GOPROGOPR9056.JPGsmall recovery time has a very good chance to get DCS….What to do, if you are spearfisher? Limit duration of your spearfishing session, have enough rest between dives, use appropriate thermal protection, stay hydrated!

Ok, what about DCS for Deep Freedivers?

Let’s say you are one of the most famous Freediver of all time, Herbert Nitsh, and diving not to 20 meters but to 214 meters!! You make a big inhale as possible (don’t forget, around 79% of inhaling air is N2) and put it under a huuuuuge pressure of 21 atm (this is what you have at 200 meters). During your descent, this N2 from your lungs will come into your bloodstream and from there to your tissues.
And now you will start your ascent. It would be No Limit discipline and you are not going to use your muscles for going up (which is very good to reduce the risk of DCS), you are probably also not dehydrate it nor cold (which is also very good)
But you are quite fast for this huge amount of N2, dissolved into your tissues. The bubbles will form. But not big in the beginning. But when you ascent with the constant speed, they are going to increase in size (because the pressure is decreasing). How to prevent it? You need to slow down…And this is what Herbert did – he dramatically decreased his ascent rate after 50 meters (from 3 m/s to about 1 m/s). He also did some safety stop at 10 meters to make it even safer. And this is how he became The Deepest Man on Earth by making a dive to 214 meters!!
But later, when he was trying to beat his own record he lost his conscious on his way up and failed to do all of the above (safety stops and slow down his speed). As a result, massive DCS….Luckily (actually his story of recovery is almost like a miracle) he survived and recovered from it!

But if you are diving not that deep, let’s say to 40 meters; is it possible to have DCS? And the answer is yes… Last year Freediving legend William Trubridge got DCS during his routine training. I mean routine for him but crazy for all of us! Let’s have a look at it

William did 5 dives to 40 meters with “hangs”. Time of each dive was about 1.50, the surface time between dives only 2.15. As a result, after his 5th dive, William felt one of the symptoms of DCS – numbness in his leg. He went to a hospital and took special treatment for DCS there (pretty expensive!).  This story has a lucky end as well, William completely recovered and competing again!

According to him, he done this type of training before (even harder) and never had any problem.

So, what is the problem here and how to avoid it? The dives were not too deep and not too long (especially if you are World Champion). But the recovery time was quite short.

So, if you are just starting freediving – this is a basic advice – DO have long surface intervals. How long? Here a couple of ways how to count it

  1. The time between your dives should be 3-4 times longer than your dive time. For example, if your dive time 30 secs, then have a rest for at least 2 mins
  2. Divide dive time by 5 and the result is a time in minutes. If you dive to 40 meters, have a rest for at least 8 mins.

And be even more conservative – have even longer rest!

A few things which I would you to remember

dcs3First of all – symptoms of DCS. Type 1 DCS – skin rash on shoulders and upper chest, joint and limb pain. Type 2 DCS – peripheral tingling and numbness, unconsciousness, respiratory arrest and paralysis, coughing, feeling of air-starving.

Second – predisposing factors. Obesity, intense exercise less than 12 hrs before diving, age, fitness level, dehydration, injury and illness, alcohol, carbon dioxide, cold. Obviously, scuba diving before freediving is absolutely no-no!

Treatment for DCS – the patient should lay down and breath 100% O2. Transportation to a recompression chamber should be organized as quickly as possible.dcs4

And one more times how to avoid DCS

  • Don’t freedive after scuba diving
  • Have enough surface interval
  • Don’t ascent very fast from the deep dive
  • Reduce the number of deep dives in one session
  • Limit the duration of the dive session
  • Stay hydrated and use an appropriate wetsuit
  • Don’t consume alcohol and don’t do intense exercise before a session

Stay safe, enjoy Freediving and educate yourself about the activity which you love!

 

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