# Emotion in an image – Pain

The heart wants to fight but the body refuses to join the fray. The pain has confined the warrior to the ground rendering him unable to continue. Restraining the urge to keep moving and hoping against hope he waits for the pain to subside knowing that it is here to stay.

-Stein

# 4 Top SCUBA Diving Myths

SCUBA diving has become a very popular sport. Everywhere there is a body of water (sea, ocean, lake) you will find most often than not a diving agency or club willing to teach you how to explore the marvels the underwater world has to offer.

However, there are still some common myths and misconceptions around that confuse and sometimes discourage non-divers to even try diving for the first time.

So, my fellow future divers (I have faith in you!) here are the 4 most common myths I have encountered during my diving days and the reality about them:

### Myth #1. Divers carry a tank full of oxygen to breathe underwater

Surprisingly no. It is true that divers carry a tank (sometimes more than one, but we will discuss that on a different post). The tank is full of widely available, common air. Yes, the tank or cylinder (if you want to sound smart) is full of exactly the same stuff you are breathing while reading this.

For the brainiacs in the audience, air has only 21% of oxygen, the rest is a combination of other gases (mostly Nitrogen 78%) including argon and carbon dioxide.

The only difference is that the air in the tank is very dry. This is necessary to prevent rusting (humidity and metal don’t get along very well) and extend the tank lifetime.

There are special cases (technical diving, enriched air, etc.) when the tank might be filled with something different but the large majority of dives in the recreational world are done with common air.

### Myth #2. Diving is all about how deep you can go

One of the most frequently asked questions I get when talking to non-divers is how deep can you go. When I tell them that my average depth is around 28 meters (92 feet) I can see the disappointment in their faces.

Depth is one of the elements about diving but not the only one. Diving is about the challenge of safely visiting an environment where humans are not commonly welcome (unless you can naturally breathe underwater, and if you can, please contact me immediately).

It is also about exploring the underwater world, full of life and colours that cannot be found elsewhere. It is about the excitement of visiting a sunken ship and imagining what life was onboard while exploring the scattered remains of the ship now home to countless different species of fish and coral.

The depth and the resulting increased pressure is something that divers spend a great deal of time understanding during training. In the end, all divers learn how depth and pressure work, but most importantly learn to respect them.
Different levels of diving certification will give you access to better dive planning and greater depths. But for recreational purposes, the depth limit is set at 40 meters (130 feet). Anyone that tells you stories about going deeper than that without the proper training/equipment is either lying or taking unnecessary risks.

The good news is that most of the life, action, and excitement can be enjoyed in the 10-25 meters (33-82 feet) depth range. So, as you can see, is not only about how deep you go but also about the entire adventure of discovering what the underwater world has to offer.

### Myth #3. Shark Attacks

Thank you Hollywood and news outlets! Sadly when a shark attack occurs, the media immediately jumps and describes every gruesome detail of the incident and give the audience the impression that this kind of events is a common occurrence.

Nothing farther from the truth. Sharks are majestic creatures that will happily share their environment with the occasional visitor.

To put some perspective, consider that there are around 6 million active divers worldwide1 and according to the international shark attack file, between 1958 and 2016 there have been 2,785 unprovoked shark attacks, of which 439 were fatal2.

Simple math tells that: 0.0004% of active divers were attacked during a period of 58 years! Out of these incidents, 0.00007% were fatal. This is something the news outlets do not share when broadcasting a shark attack report.

To put even more perspective, according to the “list of 18 things more likely to kill you than sharks”3 available on the same report, it is far more probable to die of sun exposure, lighting or fireworks than a shark attack.

So, no, a shark attack is not something you should worry about while exploring the underwater realm. If you ever see one don’t panic, show respect and take a great picture! It will definitely grant you bragging rights.

### Myth #4. Diving is a sport for guys only

No! No! and No! There is nothing that suggests that diving is a guys only club. On the contrary, most diving apparel companies produce equipment and apparel that caters for the girls’ needs and tastes.

There is also a growing number of female diving personalities and ambassadors that prove that diving is an all-inclusive sport.

The only requirement to get into diving is to get a proper training and certification from a reputable agency. There is absolutely no difference between males or females when it comes to the requirements and qualifications to get certified.

So, please if you want to dive, just go and do it! You will find that there are training alternatives available that will allow you to “discover” the experience before you commit to getting a full certification.

So, I hope that this clarifies a little bit more the wonderful world of underwater exploration and wish to see you soon making bubbles and enjoying the under the sea view.

-Stein

# Emotion in an image – Hopelessness

When all is lost, even hope, the spirit breaks surrendering the will to fight. Probably the most terrible moment in one’s life.

# Emotion in an image – Confidence

Continuing with the emotions in an image series the next stop is confidence.

I struggled with this one since the focus was self-confidence. The ability to trust in one’s abilities to face any challenge knowing that victory is always at hand.

I hope you enjoy this image and please let know what you think in the comments section.

-Stein

# Emotion in an image – Depression

Describing an emotion with words is not always easy. It might be because an emotion is a complex combination of many things that are happening to us at the same time: The feelings, the place, the people around, the surrounding sounds and aroma, the sun setting in the distance all these contribute to convey a particular “emotion”.

The old “an image is worth a thousand words” saying is very true when it comes to representing emotions.

For this, I have started a personal project to create a set of images that I hope help to transmit the “true” feeling of a particular emotion.

Enjoy the images and let me know what you think in the comments section.

-Stein

# “Why? Because Science!” is LIVE!

A fellow blogger has released after much work and effort her first book. I am personally attracted to the subject as it deals with science. If you have a chance, check it out.

Ladies and gentlemen, it gives me orgasmic pleasure to announce the grand arrival of my book, “Why? Because Science!” It drops TODAY on Amazon so click on the link below and get your electronic copy!

It would also be super awesome if you could help me promote this by sharing the link to your social media, recommending the book to friends, leaving a review on Amazon, and forcing it upon family members for Christmas. If this is going to be a success, I’m going to need all the help I can get from you, my blog family. And if you do help to promote the book on social media, please tag my Facebook page @whybecausescience in your comment, status, share, etc!

I’d really appreciate it. Happy reading, everyone!

Amazon: Why? Because Science book

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# The weight problem

The human body is naturally buoyant (it floats). For this reason, a scuba diver must add weight (usually in the form of a weight belt with lead blocks) to ensure he or she will be able to descend and ascend in a controlled manner.

Due to the multiple factors that influence the calculation of the required weight for a belt such as water type (fresh vs. salt), diver weight, body fat, gear, temperature, etc. setting it up a with the right amount of lead can be a daunting task. Especially for novice divers that are still learning the ropes of buoyancy control.

This, more often than not, leads to an “improper” weighted diver who is either too heavy or too light and struggles to maintain neutral buoyancy. As a result, the diver uses more air than necessary reducing the bottom time and increasing risk.

Many diving agencies have developed “rule of thumb” guidelines to calculate the required weight but these usually don’t take into consideration all the factors that affect buoyancy and the approximated suggestions need to be adjusted continuously.

To prevent this and help fellow divers, this paper describes the physics of buoyancy with the objective to describe a more accurate method to calculate the weight requirements for any diver and condition.

So, buckle your belt up (no pun intended) take your calculator out and get ready to uncover the actual weight you need to put on your weight belt for your next dive!

# Understanding buoyancy

When a body is placed in a fluid, two main interacting forces determine if it will float, sink or remain suspended: The buoyancy force (Fb) and the force of gravity (Fg).

To determine the body behavior in the fluid consider the following table:

 Fb > Fg Floats – Positive buoyancy Fb < Fg Sinks – Negative buoyancy Fb = Fg Neutral – Neutral buoyancy

## Determining the buoyancy force (Fb)

Buoyancy force is determined by three factors:

• The submerged volume of the body (Vs)
• The density of the fluid (D)
• The force of gravity (g constant with a value of 9.81 Newtons/Kg)

Buoyancy force is calculated with:

$F_b =D\times V_s\times g$

### Calculating fluid density (D)

Diving only happens in water! This makes the fluid density calculation a bit simpler, however, there are a couple of things that must be considered: Water temperature and salinity. To determine the density, use the following table(1):

 Temperature (Celsius) Fresh water $\frac{kg}{mt^3}$ Salt water $\frac{kg}{mt^3}$ 4 1000 1024 5 1000 1024 10 999.98 1024.94 15 999.2 1024.15 20 998.3 1024.22 25 997.1 1022 30 995.7 1020.56

### Calculating the volume (Vs)

For diving, this is the most complicated element to calculate. Several factors must be considered to accurately determine the submerged volume. To simplify the calculation, only the most relevant variables will be taken into account:

• Body weight
• Body composition: since fat floats and muscle tends to sink, this must be considered on an individual basis
• Tank weight and volume

Body volume: to calculate the diver’s body volume, it is necessary to determine the amount of fat and muscle. I suggest that a simplified version of this calculation can be done by using the body mass index (BMI) as a guideline. To calculate BMI(2):

$BMI=\frac{(\frac {weight (kg)}{height (mt)})}{height(mt)}$

BMI can be related to the percentage of body fat and body density according to the following table(3):

 Category BMI Body Density Fitness <18.5 1.282 Normal 18.5 – 24.9 1.01 Overweight >25.0 0.808

With these elements, diver body volume (Vd) is calculated with body weight (Wd) and body density (Dd) with the following formula:

$V_d=\frac{(\frac{W_d\times 1000}{D_d})}{1\times 10^6}$

Note that the operations with the constants (1000 and 1×106) are used to maintain the unit of measure integrity. The final result is expressed in m3.

Tank volume: For an accurate volume (Va) calculation it is necessary to take into account pressure after compression (Pc – typically 210 bar), Volume of gas after compression (Vc – typically 11 lts) and atmospheric pressure (Pa – constant 1.01 bar). This is expressed in m3 and determined by:

$V_a=\frac{P_c\times V_c}{P_a}\times 1.225\times 10^{-3}$

Total volume: Once these elements have been calculated, the diver total submerged volume is obtained as follows:

$V_s = V_d + V_a$

## Determining the force of gravity (Fg)

Gravity is calculated considering: The total weight (W) and the force of gravity (g)

$F_g = W\times g$

Calculating total weight (W): To calculate the total weight consider the two main elements: diver weight (Wd) and tank weight (Wt).

$W = W_d + W_t$

Tank weight (Wt) varies depending on the material (steel or aluminum), volume and ambient temperature. To determine the total tank weight use:

$W_t = W_e + (V_a \times d)$

To determine the tank weight (We) refer to the following table(4):

 Tank Weight (Empty) kg Aluminum 11 lts (AL80) 14.2 Aluminum 13 lts (AL100) 18.5 Steel 11 lts (Steel 80) 12.7 Steel 15 lts (Steel 108) 20.8

The weight of the tank gas will vary depending on volume and temperature. To determine the density (d), refer to the following table(5):

 Temperature (Celsius) Density (kg/m3) 5 1.269 10 1.247 15 1.225 20 1.204 25 1.184 30 1.165

## Calculating the required weight

Once the buoyancy and gravity forces have been calculated. the required weight (in kg) for the belt can be calculated with:

$B_w = \frac {F_b - F_g}{D \times g}$

### Compensating for exposure suit and other gear

Divers wear a variety of exposure suits to adapt to different conditions such as water temperature, potential hazards, etc. To calculate the required weight to compensate (Wc) for exposure suit buoyancy consider the following table:

 Add per mm (fresh water) Add per mm (salt water) Exposure suit Kg Lbs Kg Lbs Full body 1 piece 0.884 1.95 0.907 2.0 Shorty (no sleeves) 0.442 0.975 0.435 1

If the diver is wearing extra gear, add the required weight to compensate according to this table:

 Fresh Water Salt Water Additional gear Kg Lbs Kg Lbs Hood and gloves 0.435 0.96 0.453 1

### Calculate the total weight

The total weight belt (Wt) will be determined by Bw plus the required compensation for exposure suit and other gear (Wc). Additionally, due to the weight blocks availability at most diving shops, this number needs to be rounded.

As a safety measure and personal preference, a margin of +/- 10% can be factored into the final calculation to get the recommended weight belt range:

$W_t = round(B_w+W_c)$

Recommended weight range = Wt +/- 10%

## Putting it together, a practical example

The best way to understand these calculations is with real life example:

A diver needs to calculate the weight for the belt:

• Diver weight: 86 kg
• Diver height: 1.70
• Water: Salt @ 20 Celsius
• Tank: Steel 11 lts @ 210 bar
• Exposure suit: full body 5 mm
• No hood

### Calculate Buoyancy force (Fb):

$F_b =D\times V_s\times g$

Density (D) = 1024.22 $\frac{kg}{mt^3}$

Volume (Vs):

$BMI=\frac{(\frac {86kg}{1.70mt})}{1.70mt}=29.7$, then Dd=0.808

$V_d=\frac{(\frac{86kg\times 1000}{0.808})}{1\times 10^6}=0.106mt^3$

$V_a=\frac{210\times 11}{1.01}\times 1.225\times 10^{-3}=2.801mt^3$

$V_s = 0.106mt^3 + 2.801mt^3=2.907mt^3$

$F_b =1024.22\times 2.907\times 9.81=29\times 10^3 Newtows$

### Calculate force of gravity (Fg):

$F_g = W\times g$

$W_t = 12.7 + (2.801 \times 1.204) = 16.07 kg$

$W = 86 kg + 16.07 kg = 102.07 kg$

$F_g = 102.07\times 9.81 = 1.0\times 10^3 Newtons$

### Calculate the required weight (Wt):

$W_t = round(B_w+W_c)$

$B_w = \frac {29\times 10^3 - 1\times 10^3}{1024.22\times 9.81} = 2.78kg$

compensate for exposure suit:

$W_c = 5 \times 0.907 = 4.53 kg$

$W_t = round(2.78 + 4.53) = 7 kg$

Recommended belt weight range: 6 kg – 8 kg

## Final notes and recommendation

Please note that to give credit to the sources that were used during the preparation of this paper, links have been added where you can click for further reference.

Remember that it is recommended that a buoyancy check is performed every time you change the diving environment, gear or conditions. Ensuring that you are properly weighted will make the experience safer and more enjoyable.

Feel free to distribute or copy this material as long as you provide a reference to the source.

Obviously, the author can not take any responsibility on how a diver applies this information.

Happy diving!

-Stein