Motor skills and situational awareness: pro tips for diving students

Motor Skills and Situational Awareness– Tips and Advice

Diving students can be overwhelmed by the number of complex motor skills that they need to learn and develop as they progress through the Open Water course and gain experience as certified divers. It takes time and practice to get the hang of it.

One way to learn is to break down a complex series of actions into their individual components, then think it through and visualize yourself performing each discrete step. As you practice in your mind, gradually increase your speed until you achieve a fluid motion.

Mask Clearing

There are four discrete steps to take to clear water out of a flooded mask. With practice, these will all flow together.

  1. Look upwards to pool the water at the bottom of the mask.
  2. Press your fingers against the top rim of the mask to hold the seal against your forehead.
  3. Inhale deeply through your regulator.
  4. Exhale with gentle force out your nose...snort!

Repeat as many times as necessary.

To visualize this process, imagine that you're blowing your nose into a kleenex tissue.  When you blow your nose, you position your fingers to press against your cheek bones. So when clearing a mask, imagine you're blowing your nose…. but press your fingers against your eyebrows.

What happens when you perform this skill is that when you exhale out your nose, the increased air pressure inside the mask will break the seal against your skin just above your mouth and the air pressure will force the water out the bottom of the mask where the seal has been broken. Too easy!

Mouth breathing

Your nose has only two functions inside a scuba mask: to equalize mask pressure and to blow out any water that has leaked in. Both involve exhalation only. Your nose serves no other purposes, so you need to practice to become a mouth-only breather. Many new divers have some difficulty adapting to this, so I recommend that they practice mouth-breathing at home. Plug or pinch your nose, relax and breathe deeply into your diaphragm. Exhale fully. Wait for the breathing reflex to kick in, then inhale fully once again. Do this exercise for a couple of minutes every day. 

Buoyancy Control

Buoyancy control is possibly the most critical dive skill. It's all about developing a situational awareness to control your body position and movement in three-dimensional space, so that you can multitask. You manage your buoyancy using three air vessels, or balloons: The BCD, which contains an air bladder, your drysuit, which is a sealed air vessel, and your lungs (breath control). A 4th component of buoyancy control is effective body positioning and efficient propulsion/finning to keep forces in balance.

Most new divers have some challenges attaining neutral buoyancy and staying neutral throughout a dive, especially when hovering in place. It’s common for new divers to get caught up and struggle in a zigzag pattern where they can't control their body position and depth for any length of time. Zigzagging up and down can occur for several reasons: A diver might not have the situational awareness to realize that their depth is changing until it's too late, they might be too slow to react,  they might overcompensate for a small changes in buoyancy, or they might be have ineffective body positioning and propulsion skills.

To understand what is happening to such a diver, visualize a tug of war rope, with forces trying to make you float pulling one way and forces trying to make you sink pulling the other.

Visualize that you’re all geared up and in the water, floating on the surface but not swimming. Forces to make you sink include your body weight plus the weight of the gear you’re wearing. The force trying to make you float is the volume of water that you’re displacing. The more water displaced, the more buoyant you will become. If your BCD is full of air and there is air in your drysuit,  you’re displacing the maximum volume of water and will float high on the surface. If you now purge excess air from the drysuit, exhaust air from the BCD and exhale to empty your lungs, you’ll displace much less water, so the weight of your body and equipment will cause you to sink.

The BCD contains an air bladder - a big balloon - which is your main tool for establishing and maintaining the balance between the forces to sink and to float. Its’ low-pressure inflator/deflator hose is the equivalent of a car’s steering wheel. You need to be holding onto it at all times (except when checking your gauges) and making lots of small adjustments just like you would driving your car on city streets. As you dive deeper, air in the BCD will be compressed by  the increasing pressure, so you need to add air to maintain neutral buoyancy and prevent sinking. Conversely, as you move up from deeper water to shallower water, pressure decreases so the air in your BCD will expand. You will need to exhaust air from the BCD to maintain neutral buoyancy and prevent an out-of-control ascent.

Imagine that you’re mid water and hovering motionless, neutrally buoyant. If you press the inflator valve for one second, to add air to the BCD, you will become positively buoyant. You will feel the weight of the BCD lifting off your shoulders and pulling you upwards, slowly at first, but then accelerating faster as the air in the BCD, drysuit and lungs expands. 

Or, from a neutrally buoyant position if you instead held the exhaust button down for a second, the BCD would dump air and feel heavier on your shoulders. You'd start to sink slowly, then accelerate downward as air in the BCD and drysuit compresses. 

Your drysuit is connected to your tank air by a low-pressure hose. You control the volume of air inside the drysuit with an inflator button and an exhaust valve, like with the BCD.  To maintain neutral buoyancy, add air when you're descending and exhaust air when ascending.  Use your right hand to deploy both the inflator and deflator buttons.

If you're wearing a drysuit and you let your arms go weak/limp and fill up with air, you'll create bulging balloons of air at your shoulders, with little air around your lower body. This will throw you off-balance, and will often cause you to become positively buoyant. And it can cause the air bubble to escape through your neck or wrist seals, which will let water in to the drysuit. Keep your arms tucked in close to your body!

Skilled drysuit divers will set the drysuit exhaust valve to the closed position during the descent, then open up the valve when at depth. Once the exhaust valve is opened, the drysuit will automatically exhaust excess air. This means that anytime the diver feels positively buoyant, all they have to do is rotate/roll their left shoulder upward for a couple of seconds to let the excess air exhaust itself, then rotate back to down to level their shoulders.

Propulsion techniques

All your underwater propulsion comes from the action of finning. It's a waste of energy and tank air to use your arms for propulsion. And multitasking is impossible if you're using your arms for propulsion. Your fins are big paddles, designed to maximize propulsion. Proper, effective and efficient finning techniques take time and practice to develop. And effective propulsion is a critical component of buoyancy control.

For faster swimming speeds, the thrust comes from your hips and thighs. To visualize how this works, lie down on the floor on your back and put a pillow under your knees, to keep your legs somewhat bent. Imagine that the ceiling above you is actually the seabed below you. Keep your toes pointed, then raise and lower alternating legs…left up, right down, left down, right up. Notice that the upward thrust is from your hips and thighs. The action is very much like walking. Of course, you are doing this on the floor at home facing the ceiling. In the water, facing the bottom, the thrust is on the down-kick. Visualize in your mind that your fin tips are like palm trees swaying back and forth in the breeze. Keep your knees and ankles loose. Propulsion is best when you follow through and not cut the fin-kick cycle short. 

For slower swimming speeds, for example when you’re scoping out a small area, thrust comes mainly from your calf muscles, or below your knees, because you don’t need the full energy that comes from your hips and thighs. To visualize this, lie down on the floor face down. Bend one leg up from the knee. The thrust force comes in the action of straightening your leg…the downward thrust. While one leg is thrusting downward, the other leg is bending upward. In reality, there will be some thrust that comes from your thighs, but most of it will come from your calves.

When ascending vertically straight up, like at the end of a dive, keep your legs straight but loose and your toes pointed downward and your ankles loose, thrusting from the hips.

Many new divers become fatigued by water resistance against their fins as they swim around. To avoid thigh muscle burn, many novices take a shortcut and swim like they’re riding a bicycle or climbing a ladder. Of course they need to kick at twice the speed to make any forward progress, so this finning technique is very inefficient.

Most 40 minute dives cover a distance of 500m or less. Some of this bottom time will be spent hovering in one spot, some time swimming slowly and some time swimming faster between points of interest. Different finning techniques can be used in each situation.

It’s a waste of energy to use your arms for propulsion, so the proper swimming position is with both arms folded loosely across your torso to minimize drag, with the low pressure inflator in your left hand. Arm movements are really only useful for close-in maneuvers and sharp turns.

Situational awareness when inflating or deflating the BCD or drysuit: estimating volume changes by proxy (sound)

It's not possible to estimate the physical volume of air that's being pumped into or exhausted from the BCD or drysuit at any given moment during a dive. You keep track of this net volume by proxy: by estimating the number of seconds that you've pressed the inflator button or exhaust button. The only way to do this is by listening to the hissing sound that's made by the inflator valve, and the bubbling sound made when air is exhausted.

It’s important to add or exhaust air in small increments, to avoid overcompensating and flinging yourself in the opposite direction. The proper way to hold the BCD inflator hose is in a pistol grip,  with fingers and thumb positioned to press the inflator and exhaust buttons as needed.  With this kind of grip, you will be able to make quick adjustments and even be in position to inflate your BCD orally if necessary.

If you're adding air to the BCD to offset negative buoyancy, do it in one-second increments and listen to the hissing sound to estimate this duration. Use your inner voice to count "one thousand and one". Wait a few seconds to estimate how much this additional air has changed your buoyancy. If you're still negative, press the inflator and count "one thousand and two". 

If you need to exhaust air, lift your left arm as high as it will go as you press the exhaust button, to make sure that air is efficiently exhausted from the BCD. Watch the bubbles as you exhaust the air, to see how much you have dumped. And listen to the bubbling sound this air makes as it exits the BCD, to estimate the number of seconds of air that you've exhausted.

While some new divers tend to positive buoyancy, others tend to keep sinking. Resist the temptation to swish your arms when you’re sinking. It’s too little compensation and a waste of energy. Instead, squeeze the inflator button for one second, wait a moment to see if you've added enough air, and if you need to add more then add air in one-second bursts.

Body positioning, centre of gravity, and centre of buoyancy

Poor body positioning and a bad finning technique can also affect your buoyancy. Ideally, you want your body to be almost horizontal in the water so that you’re swimming horizontally and maintaining a vector that keeps you at a constant depth. Your knees should be below your shoulders. It takes proper weight distribution and strong core muscles to control your body position and centre of gravity underwater, so work on your abdominal strength!

Most body weight and lead weight are located around a diver's mid-section, with lead weights positioned close to the belly. This is the diver's centre of gravity, and it acts like a boat's keel. The diver's centre of buoyancy is located above the centre of gravity, around the lungs and the BCD's air bladder.

When a diver is swimming along, it's helpful to use a visual "spotting" technique to support proper body positioning and to provide a visual destination to swim towards. This involves looking ahead in your direction of travel, seeking to visually spot and fix something in the distance that you can swim towards. This technique helps to maintain situational awareness of your depth, speed of travel, visibility conditions, etc. 

Breath Control

Breath control is a critical dive skill that can only be mastered over time. It's not just about breathing, it's about consciously managing your respiration and keeping your heart rate down to prevent overexertion and rapid air consumption. 

Imagine that you’re underwater and neutrally buoyant, hovering motionless because the forces are in balance. When you inhale, your lungs expand and you displace a little more water so you’ll tend to rise slightly. When you exhale, you tend to sink slightly. If you breathe calmly, deeply and rhythmically, your breathing won’t affect your overall buoyancy. But an anxious diver will breathe fast and shallow, and tend to become positively buoyant. Also, by not inhaling deeply and exhaling fully, they'll fail to eliminate carbon dioxide, so the breathing reflex will continually be triggered. This failure to breathe and oxygenate fully can easily cut bottom times by 50% as the anxious diver sucks the tank dry.

Incidentally, good breath control skills will enable you to fine tune your vertical position in the water column without adjusting the volume of air in your BCD or drysuit. This is an especially important skill for photographers when hovering around a subject.


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Posted on February 17, 2013 .