Immersing DiveBud to extreme depths

Before offering our freediving computer to professional freedivers we wanted to make sure that it can withstand any challenging depths that freedivers would expose it to.

Device test-ability could be a major limiting factor for a small company like ours, so we considered our options very carefully. We have designed DiveBud to withstand a very high pressure. However, any theoretical aspects have to be verified empirically with laboratory tests. To ensure quality and safety of our users and so we decided to moved forward with the tests.

pressure gauge
2 MPa reading on pressure gauge (equivalent to -200 meters depth)

We started by building a small high pressure chambers with plumbing PVC parts and tested the initial prototypes in it. Even those simple designs enabled us to test many different aspects of a freediving computer. Things like sampling control, time control, logging, sound alarm frequency, sound intensity and many others were tested in that simple small chamber. In fact, most of the early stage tests have been done using that simple apparatus. It allowed us to descend our freediving computer to depths up to 20-30 meters. We used manually operated low pressure pumps to control the pressure inside the chamber.

Then we moved towards a more reliable and industry trusted solution. The new small industrial high pressure chamber could withstand up to 8 atmospheres of pressure. This allowed us to continue exposing DiveBud to depth up to 70 meters.

Industrial grade pressure chamber

This chamber was still under manual operation and we used an automobile foot pump to achieve maximum pressure in the testing chamber. Very soon we realised that the pump itself is a limitation as it couldn’t produce pressure higher than 8 atmospheres.

It was time to test our freediving computer at extreme pressures, so we ordered a 30MPa automatic pump. Assembly of the new pressure chamber was the most interesting part of the job. The chamber was smaller compared to the previous cambers. However, it could withstand an enormous pressure.

We conducted a series of tests and exposed DiveBud to pressures of 100, 150, 160 and ultimately all the way up to 210 meters:

DiveBud dive log recording a dive to 164 meters
DiveBud dive log recording a dive to 208 meters

Also, we conducted a separate test to see how much pressure can the sensor seal hold. I held pressure equivalent to 300 meters depth in salt water.

Now we are absolutely sure that DiveBud is ready for the world’s deepest dives.

How to know the depth without a diving computer?

In this article we are going to discuss alternatives to dive alarms in a diving computer or how to know what depth are you at during freediving. Let’s start with answering why freedivers use alarms?

First and the most obvious answer is to know where we are. During the freediving we are trying to relax, get into inner state of the mind to conserve the oxygen. We experience lots of fun during a free fall, it is the moment of the dive when we pass the point of the neutral buoyancy and fall down being negatively buoyant. We relax and phase out, we embrace the feelings of the depth, or just observe the surrounding.

Suddenly, we would like to know where we are? What is the depth? Is the time/depth to turn back?

ocean freediving
Freediving in the ocean

Knowing where we are is very important to stay calm and relaxed, to know we did not pass safety limits of our body. At big depth it gets darker and that is where conventional diving watch does not help us, because we can not see the readings. The situation is even worse in lakes, where visibility drops very dramatically with depth.

I still remember my shock when I was diving in Burrinjuck Lake where at 12 meters of depth I could not see my bright yellow line holding it right in front of my mask. That day it took my some time and visualization to go beyond 20 meters as I was so not used to the darkness.

Using dive alarms instead of reading the number from the watch comes to rescue in those situations. If you have a diving computer like DiveBud you can set depth alarms on descending and ascending depths as well as hanging alarms(time passed since certain depth is reached.).

The second situation is mouth fills, when we dive beyond our residual lungs volume. We would like to know when to do the first and the second mouth fills or start the free fall, for example.

The third situation is about target depth or approaching the target depths. One of my friends told me a story, how he was training for the freediving depth competition and one day he could relax so well that he almost forgot about the turn at the bottom plate. His body passed the bottom plate and a waist-attached lanyard suddenly caught his body exposing him to quite an extreme stretch. That was very dangerous for his lungs as at the big depths we avoid stretches as much as it is possible. So it is recommended to set alarms or be aware of the depth as we approach the target depth and be notified 5-7 meters before to prepare for that.

But what else can we do to know where we are when we are freediving?

The first option is to dive along the marked line and know exactly what do markings mean on it. This is a common practice in training in warm and clear waters, where you can look at the markings or at your watch, but this would not work at the dark lake.

The second option is to count your strokes, kicks or count in your mind. It only works in the beginning of the dive as when we pass the neutral buoyancy point we just fall down and can use this information.

The third option is to count you equalizations. If your equalization is very stable then counting how many equalization movements did you do can be a good indicaton on what depth are you at. For example, I know that it takes me 9 equalization movements to get to 25 meters.

Lastly, you can check nautical charts to see what is the depths in the region where you are going to dive and relying on your vision stay away from the very deep spots. In Sydney, Australia we recommend one more method which is based on visibility of the water. Most of the time the visibility in the bays is between 8-12 meters, so if a freediver sees the bottom it is about 12 meters max, so depending on the level it could be safe to proceed. If you don’t see the bottom, then you need some instruments to help you understand where you are in terms of the depth.

Freedive with a good company!

Analysis of dive logs from a freediving smartwatch

Recently my freediving buddy Luke had used freediving smartwatch DiveBud at freediving competitions in Mexico. He did very impressive constant weight dives and we can share his two most impressive dives here today. We will analyse a freediving performance based on readings of the freediving smartwatch recorded and compare it to some references.

His first dive which we downloaded from his freediving smartwatch had 60 meters maximum depth and lasted just over the two minutes time:

freediving smartwatch diving log

Notice how the graph of the dive is sensitive to body movements of the freediver and we actually can calculate how many strokes Luke did on the way up and down. Clearly Luke did 5-6 strokes on the way down, which is considered to be a very good number.

The less effort a freedivers spend on the way down the more relaxed they are, so 6-7 strokes is considered to be a good number of strokes on the descending in constant weight with no fins (CNF). By the time of first minute Luke reached depth of 56 meters. And on the way up it was about 30 strokes. Timings of the strokes are very consistent, which indicates that a diver had a good form and was relaxed on the ascending.

Let’s look at the second and the deepest of Luke’s dives where freediving smartwatch DiveBud recorded 64 meters depth.

Try to guess how many more strokes my buddy had to do extra to get to +4 meters depth?

freediving smartwatch diving log

Here we see same 6 strokes on descending and by the first minute he reached depth of 57 meters, a very consistent descending performance between two dives. On the way up though Luke did about 36 strokes and there is noticeable difference between first a few strokes and the rest of the dive. So 6 strokes seems like a lot to overcome 4 extra meters of the dive and it is clear that Luke can improve this performance.

Let’s compare this dive for example with Dean Chaouche’s CNF dive to 82 meters with time 3 minutes 12 seconds(national record of Great Britain). We counted his strokes during the video and found that he did 7 strokes on the way down and 28 strokes on the way up, so clearly it was more efficient dive.

World freediving champion William Trubridge said: “I am definately an advocate of counting strokes and using alarms, they are realy important tools. You can listen to your alarms subconciosly…” when spoke in this podcast episode and his view is that a freediver benefits from depth alarms and should count their strokes to improve the efficiency of their dives. These are essential tools of freediving athletes. Will recommends on the first 3 strokes saying that first three strokes should be continues (no glide in between), strong and efficient and it takes 7 stokes for him to descend. Will sets a depth alarm 7 meters before the plate to extend an arm and get ready for the turn. He also recommends spending more time practicing a free fall at comfortable depths.

We were able to analyse my freediving buddy performance using shared dive logs from freediving computer DiveBud. Users of DiveBud can now upload their dive logs to this form and get a picture URL back for sharing. This allows freediviers to share their dive logs and analyse them.

Freediving gear most important item?

What is the most important part of freediving gear? Well arguably it is a mask, fins and weights. Or may be it is a dive computer? Without a mask a freediver can not see much under water, however as experience of a diver growths and depth grows some people switch to no mask noise clip freediving. As for fins – they are certainly recommended for recreational use as they ease the self propulsion, however dynamics no fins and constant weight no fins performed without fins. Weights? In the warm waters divers may choose to not use weights, especially if they go deeper than 20 meters.

So what about reliable freediving computer? Divers need an reliable instrument for depth and dives tracking and our memory not always great source for storing such an information. That is where dive computer is coming into play. This is important because freediver needs to know their depth limits for safe progression. So, freediving dive watch is arguably one of the most important feediving gear divers should get.

In DiveBud we create a day ordered list of dive logs:

How many times divers struggle with cable not working or watch that requires an extra cable (to purchase separately) to download dives. DiveBud naturally integrates both dive logs and devices controls into wireless interface and allow for users to access their data seamlessly without any additional gear required.

DiveBud also allows you to share your data, so that your dive logs belong to you.

Get your DiveBud today.