Tec Clark, Author at ScubaGuru

What does SCUBA stand for and how did it get its name?

As a scuba instructor I am often asked “what does scuba stand for?” The word “scuba” is an acronym for Self-Contained Underwater Breathing Apparatus. Webster’s Dictionary defines scuba (scu·ba) as “an apparatus utilizing a portable supply of compressed gas (as air) supplied at a regulated pressure and used for breathing while swimming underwater“. Although an acronym, the modern word scuba is acceptable in common case and does not need to be written as all capitals (SCUBA) nor with abbreviation (S.C.U.B.A.).

The acronym was coined by Dr. Christian Lambertsen in 1954. While at the University of Pennsylvania Medical School, Dr. Lambertsen worked on the first prototypes of rebreathers for military frogmen. He created the Lambertsen Amphibious Respiratory Unit, a.k.a the Lambersten Lung. Dr. Lambertsen gave these units the military code name of S.C.U.B.A. as they were a self-contained underwater breathing apparatus.

After his graduation from medical school, the Office of Strategic Services hired him as a 1st Lieutenant with the Army Medical Corps. He made significant contributions to amphibious units of the U.S. Military with his focus on breathing gases and decompression theory. Dr. Lambertsen laid the foundation for the modern-day rebreathers and for the use of enriched-air nitrox. He, along with Cmdr. Doug Fane, were the first to use rebreathers to exit a submarine in 1948.

Dr. Lambertsen went on to be medical faculty of the University of Pennsylvania. He is also the founding president of the Undersea Medical Society, now known as the Undersea and Hyperbaric Medical Society (UHMS). The U.S. Navy Special Warfare community gave him the distinction as “The Father of U.S. Combat Swimming”.

Dr. Lambertsen is featured as a Legend in Diving in the International Legends of Diving. You can learn more about Dr. Lambertsen here.

How to Select the Best Scuba Class

By Tec Clark 3 Comments

dive shop scubaguru — Good scuba training is important to your success as a diver. Do not seek the cheapest and quickest scuba classes.

When deciding to take a scuba class, the non-diver has very limited insight as to what to look for in selecting the right scuba class for him or her. Many people select the cheapest and/or quickest scuba class, but that can be a big mistake. Here we will explain in great detail the areas to consider when selecting a scuba class.

There are definitely some things to look for when selecting a class, dive shop, and/or a scuba instructor. Your question can be broken down into three distinct areas to evaluate, thus it is worthy of three separate articles which I have written. Let’s take a look at each of these areas of consideration:
A. How to Select a Scuba Diving Class
B. How to Select a Dive Shop
C. How to Select a Scuba Instructor

HOW TO SELECT A SCUBA DIVING CLASS
Let’s start here because you will need these items to assist you in selecting a dive shop and/or independent instructor.

WHAT IS SCUBA CERTIFICATION? 
To become a scuba diver you must complete proper training and be issued a scuba diving certification, a.k.a. a “c-card”. Your training takes place under the instruction and supervision of a certified and insured scuba diving instructor. This instructor has professional training and credentials with one or more scuba diving training/certification agencies. There are several of these agencies worldwide and they are often referred to by their acronyms. Here are just some of the scuba training/certification agencies: PADI, SSI, NAUI, SDI, SEI, IDEA, PDIC, IANTD, GUE, PSAI, CMAS, BSAC, and L.A. County to name a few.

Note: Although there are several agencies that offer beginning/basic courses to become a certified scuba diver, it is important to note that they do not all call the class to become a certified scuba diver the same thing – in fact the same named class, for example “Scuba Diver” may have a totally different meaning from one agency to another. Common course terms are Open Water Diver, Scuba Diver, Basic Diver, with most agencies using the term Open Water Diver.

An Open Water Diver scuba class is broken up into three distinct sections of training: academics, confined water and open water. Those areas of training vary by agency, region, dive shop, and instructor. You will find the packaging of this training to be varied as well, especially in pricing and scheduling. Let’s take a close look at each:
1. Academic Training (aka “Classroom Sessions”)
This training refers to the didactic (educational) learning of becoming a scuba diver. The media for academic delivery varies by training agency and instructor but is for the most part a combination of books, videos, and instructor presentations. On-line learning is becoming quite a popular alternative since the pace of learning is up to you and can be done at your leisure. Areas of learning include diving equipment, diving science, diving physiology, dive table usage, and the diving environment.
Tec’s Tips:
1. Think about your personal learning style and then choose the academic medium that fits you.
2. Take a look at a sample textbook.
3. Some agencies will have a demo of their online program that you can check out.
4. Ask how many instructor presentations (classroom sessions) there are. If there are some, you might be able to check out their classroom – is it comfortable and conducive to learning?
5. Try to meet your instructor. Is he or she someone you feel comfortable with learning from? You’re looking for good communication skills, a warm and caring personality, and a genuine passion for wanting to teach you how to scuba dive.
6. If you’re okay with reading, you like the classroom environment, and you like the instructor, then go with the textbooks. If not, then perhaps the online learning would be a better option for you. Students who are very inquisitive and like to understand things at a higher level often do better with more instructor contact hours, such as using the textbook with multiple classroom sessions.
2. Confined Water Training (aka “Pool Sessions”)
Confined water is basically the “pool session” part of a scuba diving class. Confined water training is conducted mostly in pools, however the term also refers to a controlled body of water that has “pool-like” conditions. Confined water training is where you will be introduced to, and practice, your diving skills. Skills include how to breathe underwater, how to clear your regulator, how to monitor your air supply, establishing neutral buoyancy, clearing your mask, entering the water, exiting the water, and how to assist your buddy – just to name a few.
Tec’s Tips:
1. The pool depth can be very beneficial to your training. The deeper the pool, the better. Pools that are 9′, 10′ or 12′ feet are really good depths to train in. Some pools that have deep diving wells 14′ to 18’+ are even better. But small, shallow 6′ pools are not ideal for training.
2. What is the water temperature? You want a heated pool. Some competitive lap swimming pools are a tad too cold for extended time underwater. In some training settings a wetsuit will help. Being chilly during training distracts you and can be problematic.
3. Ask about additional time for practice or skill development. Some people may take longer than others to master a particular skill. Classes have scheduled pool times that may not be enough for you. Find out the details if you need more pool sessions. Don’t race through a course just because that was the schedule. If you need more pool time to be comfortable and confident, that is a good thing.
4. Where is the pool? Sometimes the pool sessions are conveniently located – perhaps at the dive shop, local YMCA or local municipal pool. Other times the pool is quite a distance away. Again, just like the classroom, check out if the pool is convenient, comfortable and conducive to learning.
3. Open Water Training (aka “Checkout Dives”)
In your open water training, you will apply the skills learned in the confined water sessions in an actual diving environment. This open water environment is most often the ocean, but can also be lakes, rivers, quarries, sinkholes, springs and even, in some cases, man-made environments like aquariums. In the open water training you will learn a few new skills such as navigation, beach entries, or dive boat operations; and you will also be evaluated by your instructor to see how well you apply skills on your own such as monitoring your air supply, having proper buoyancy, and being a good dive buddy. Most courses will have you complete four open water scuba dives with perhaps a skin dive as well.
Tec’s Tips:
1. Where are your dives? If possible, try to have your open water dives include ocean dives off a charter dive boat. The reason for this is your c-card will allow you to dive on recreational dives all over the world – the majority of which are coral reefs – in the ocean – where only dive boats can access them! If all your open water training dives take place in a lake, then you have not learned how to set up on a dive boat, dive boat etiquette, listening to briefings, dive boat entry and exits, currents, waves, sea legs, marine life, etc. And to rely on a divemaster to coach you through all that on your first ocean dives after you are certified will be a bad experience – they are just too busy to teach you all that. Yes, there are legitimate logistic considerations that prevent all dive classes from going out on ocean boat dives, so you could consider the next tip…
2. You may consider doing open water referral dives for your open water training dives. Referral dives allow you to travel to another destination and go through your open water training dives with another instructor. This is used quite a bit for northern dive shops in the winter months. They can do the indoor classroom and pool sessions, and when completed the students go to a tropical location with paperwork in hand and finish up their open water training dives. Each agency has guidelines for this, so it is best to work with your original instructor to guide you to locations to complete your referral dives.

CLASS PRICING 
Unfortunately, this is the most complex part in the decision making process. The reason for this is class pricing varies greatly by what is included in the class and what is required to purchase additionally by the student. Avoid sticker shock – a $500 class may be the same as a $199 class! Some classes are “all-inclusive” and others are not. The details are in what is included. I have created a Scuba Class Pricing Checklist PDF for you to download FREE. Fill out this checklist as you research class prices either by calling or visiting the dive shop, or doing internet research. Then get out your calculator and add up the items on this list for a true cost comparison.
Tec’s Tips:
1. Books and Materials – are they included in the class price or are they separate? Books and materials are often bundled in a kit or pack. If you have to buy them they could be $40 to $85.
2. Online Learning – if you go with online learning, do you pay for that separately or is that included? This type of academic learning could cost $100 to $150, and you may still need to purchase supplemental materials (like dive tables and log books) to go along with it.
3. Skin Diving Equipment – Most dive shops want you to own your mask, snorkel and fins. These are very personal pieces of equipment where fit and comfort are key to their proper functioning. It is a very good practice to have your own mask, snorkel and fins rather than use rental ones. Find out if the dive shop will give you a discount for the purchase of your skin diving equipment. A 10% to 15% discount is often given to a dive shop’s students. Other shops may give a discount in the “bundling” of gear – for example mask, snorkel, fins, booties, bag, and defog solution. Prices on bundled skin diving gear range from $150 to $275.
4. Other Required Equipment – Some dive shops will require you to purchase other items in addition to the skin diving equipment. These items may include lead weights, weight belt, wetsuit, bottom timing device, dive slate, dive knife, signaling devices, and/or gloves. Although these can add up quickly, don’t look at it as a bad thing. Most dive centers that are requiring these items take diving seriously and are looking to equip you to be a more prepared diver, rather than trying to make more money on you. Chances are you will purchase most of these items soon after being a certified diver anyhow.
5. Rental Equipment – Many classes include the major pieces of rental equipment such as tanks, BCD’s and regulators throughout the entirety of confined water and open water training. Some also include wetsuits and weights. However, there are some dive shops that will include the rental equipment for the confined water sessions only, but will charge you the rental prices for the open water training dives. And, there are other places that will require you to rent an item like a wetsuit and give you an option to buy it at the end of your training.
6. Confined Water Sessions – Most dive centers will include the costs for confined water sessions (pool sessions). But there are some that may have you pay the facility entrance fee for each pool session.
7. Open Water Dives – Some dive centers will include the costs for open water dives and others will not. For example, the instructor fees and equipment fees may be built into the class pricing, but you may be responsible for paying the charter dive boat fees or dive site admission fees such as at a lake or a state park.
8. Certification Fees – Money is sent to the training agency for the processing of your c-card. Some dive shops include that in the pricing and others will require you to pay that fee. You may need to provide a passport photo or equivalent on your own, or the instructor/dive shop may take a photo of you.
9. Make-up Sessions – Find out what the costs are (if any) if you have to make up a confined water pool session or an open water training dive.
10. Miscellaneous Fees – You may find that you have to pay for parking for each pool session, classroom session or at a dive site. You may also have unique needs that could increase the cost of your training such as prescription lenses for your mask or you chill very easily and need a better wetsuit than what is offered in the rental line. And there are also tips to consider. Tipping the crew of a dive boat is customary, and many people like to tip their instructor nicely.

SCHEDULING
Look at the overall schedule of the class. Does it work for you? If not, you may need private instruction. But you want a nice, even pace between classroom, pool and open water sessions. Now, I know I am going to upset may dive professionals when I say this, but I have strong convictions based on decades of diver training and observation – AVOID SHORT, THREE DAY SCUBA CLASSES. Instead go for classes that are less rushed and offer MORE training time – especially more confined water pool time. Can an entire scuba class be taught in three days (one weekend)? Well, according to some agency standards, it can. But should it? That time frame does not work for everyone. I have seen this and even taught it on few occasions and I can say that it is overwhelming for most students. To do morning pool sessions and then get on a dive boat in the afternoon – and then do it again the next day forces important skill sets to be squeezed into too little time. It is simply too much to process adequately. Again, please consider a scuba class that is spread out over two, three or four weeks or weekends. Slowing down a scuba class lets each session “sink-in” prior to the next session. You will think of questions to ask in between the sessions as you naturally contemplate the wonderful items learned in the previous session.

On My Soapbox: AVOID CHEAP AND QUICK SCUBA LESSONS  You have to properly complete all of the required standards for training for each of the above areas. It is not hard, but it does require attention, focus and patience. Your end goal is NOT to get a c-card, your end goal is to be a good and safe scuba diver. For that reason you want to pay attention to what is being offered in each of the three areas of training. Cutting corners may have a negative effect on how good of a scuba diver you will be. I have seen so many divers take a class, go diving a couple times and then barely ever dive again. When you peel back the excuses, often you will find that a person was never a “comfortable” diver. They were told in their short class that, “they will calm down with time”, their “breathing rate will improve”, their “buoyancy will get better the more they dive”. But it does not because those items are the fine-tuning that develops under good teaching, not during the fast-paced-two-tank-dive-trip in the Florida Keys on your own as a new diver. Your confidence and comfort are very important to your enjoyment of the sport, so avoid the cheap and quick route to becoming a scuba diver, you will pay for it in the end. The more you invest in your scuba training, the more enjoyable scuba diving will be for you. Trust me.

Next article “How to Select a Dive Shop”

How to Make a Dive Pro’s Dry Bag aka Go Kit

By Tec Clark 1 Comment

For many dive pro’s working at resorts or dive centers, the ability to grab their equipment and go quickly is of importance. But it’s not only the gear bag that needs to be ready to go, it’s also the pro’s dry bag! Here we will explore the essentials of the dive professional’s “Go-Kit”.

Watch on YouTube: How to Make a Dive Pro’s “Go-Kit”

It never fails, right when you settle into your day a colleague tells you about his sinus infection (in graphic detail) and asks if you can take over his class, or work the boat, or guide the dive for the couple from New York. We have become quite good at having our equipment packed and ready to go in just a couple steps, but we often overlook the ever important dry bag AKA the “Go-Kit”. We say “As long as it has _____ in it I’m good. Well, and ____ would be good too. Oh, and _____ is important to have in there as well…” So, let’s look at how you can create your own “Go-Kit” that will enhance your preparedness to lead a dive or class. For your convenience I have selected the items in my personal Go-Kit for you to purchase at great prices through Amazon. Of course you can also get many of them at your dive center.

First, we need the right item to carry everything in:

Backpack – go with a solid construction design of sturdy zippers, multiple pockets, outer tie-downs and a durable material. It should be big enough to hold what you need, yet small enough to fit in the sometimes small dry spaces on a boat. I’m a big fan of compartmentalizing, so multiple pockets are nice for organizing. Outer tie downs are great for wet towels, bathing suits and rash guards. My personal pick is the PADI Backpack as it has all the space needs, it is well made, and it is inexpensive. However, there are many great backpacks that will fit this need.

Let’s look at all the other items by compartment:

MAIN COMPARTMENT

Clipboard – We have so much paperwork! Releases, medicals, rosters, etc. We need to keep it all dry and together. My favorite clipboard is the Officemate Slim Clipboard Storage Box It has a clipboard on the top panel, but then opens up to store your papers neatly. It has a good tight locking mechanism and it has another separate section to store pens and pencils.

First Aid Kit – For most of our diving applications off charter boats or in supervised pools there will be access to a first aid kit. But there are great advantages to having one on you at all times. I keep a DAN Guardian Diver First Aid Kit (631-2600) in my go-kit. It is small, lightweight, and has all the essentials.

Binoculars – A binocular is a great tool for supervising dives. We can use it for spotting divers’ bubbles, assessing the situation for divers giving a distress signal, and getting the name of a boat to hail them on the radio telling them they are too close to our divers’ flags – just to name a few. But when selecting binoculars we need to remember the conditions and purposes for use. We are not birdwatching! Instead, we are on a moving boat or a shore looking out over a large area of water. Too much magnification and we can easily miss what we need to look for. I like binoculars that are zoomable – I can keep it broad and then zoom in when I find what I’m looking for. You also want these things to be compact. Waterproof marine binoculars are big and cost hundreds of dollars, great for boat captains, but not so much for you. Go simple, compact and inexpensive. I recommend the Bushnell Powerview 8×21 Compact Folding Binocular Its power range is good for dive supervision needs, it comes with a case and is under $20.

Dive Reel – I can’t say enough about the need to have a reel in your go-kit. They have tons of practical uses from distance measurements, to marking, to safety stops with dive “sausages”, to search patterns, etc. One thing that is a must for your reel is to pre-loop the end and then add measurement marks to the line. You can do this with a permanent marker and tape measurer. What method of marking you use is entirely up to you. I mark my reel in 10 foot increments. I’m a fan of the Dive-Rite 140 ft Cavern/Safety Reel , either the standard or the Sidewinder, with 140’ line. It has a stainless bolt snap and the lock nut screw is metal, not plastic – a really nice improvement over their early models.

Compass – Many pro’s have their compass built into their gauge assembly. However, there is merit to having a wrist-mount compass in your go-kit. The wrist-mount compass is portable and goes with you. It stays on your arm when you have your hands full. You can pass it off to others in time of need, and is ideal for top-side search patterns when snorkeling. There are many on the market, I recommend you get one that fits you comfortable and is easy to read and use. The less profile (less bulky) the better. And make sure it has a side window.

Pocket Mask – If you get the DAN Guardian First Aid Kit mentioned above, it comes with an oronasal resuscitation mask (AKA pocket mask). However, if you don’t or you are relying on the safety equipment of the boat or lifeguard stations, I want to encourage you to at least have a pocket mask in your go-kit. I keep pocket masks everywhere – in my first aid kit, oxygen kit, gear bag, go-kit and even in my BC. Remember, since our sport is a water-based aquatic sport with multiple maladies cause by water and/or pressure, our maladies often have lots of nastiness (that’s a technical term) coming from the respiratory tracts of mouth and nose. A pocket mask is essential to your safety, plus it is the best delivery for supplemental oxygen to a non-breathing diver when you hook it up to your constant flow on your oxygen unit. I recommend the DAN Oronasal Resuscitation Mask and I recommend having more than one!

Safety Sausage – Of course we keep signal tubes (AKA safety sausages) on or in our BC’s when diving. But I also keep one in my go-kit. This comes in handy when needing to mark an area quickly like attaching your reel to it and throwing it in after an object has been dropped in the water. You can use it to mark a line, an underwater feature, as a drift signal for drifting decompression/safety stops. Note: a signal tube does not replace a dive flag. It is also a nice marker for shore entry and exit points. With so many uses and its ability to roll up into a small package I keep one in my go-kit. There are many on the market and if you are in some heavy technical diving applications do your research and go with a very robust and tall marker. But for dive supervision at the divemaster or instructor level, the one in your go-kit can be simple and functional. For this purpose I like the Innovative Scuba Concepts 45 inch Scuba Diving Dive Signal Tube with Inflator .

Dive Tool – The dive tool is a part of most of our save-a-dive kits. You could keep a full save-a-dive kit in your go-kit or in your gear bag. But when we dance around between the boat, the pool, the lake, the beach, etc. we want to be self-sufficient lest we forget items and then we are at a loss for helping the dive with minor equipment needs. I personally keep my save-a-dive kit in my gear bag, but I like keeping my dive tool in my go-kit. It has less chance of corroding. Wherever you decide to keep your dive tool is up to you, it is more about having one that will make your life easier when needed. I like the Storm Multi-Function Dive Tool but there are many others on the market that will do the trick too.

Whistle – As a pro we are required to carry an audible and visual signaling device (agency standards may vary) on our person when diving. For just a few bucks more have another whistle in your go-pack. It is a great back up, and you can use it in case of need when topside and dry. I go with the ever so popular Original Fox 40 Classic Whistle. This whistle is designed to work when wet – important for us. Plus, it delivers a powerful sound.

Water Bottle – I know, your thinking why would you talk about water bottles for your go-kit? Well, after numerous trials I identified a bottle that I really like and perhaps you can benefit from its functionality too. I have the CamelBak BPA-Free Better Bottle with Classic Cap . There are many reasons I like this. First, get away from bringing throw-away plastic water bottles on your dives. We really need to practice what we preach about environmental concerns for our oceans. Go with one reusable bottle for your go-kit. This is modeling great eco-friendly behavior to other divers and your students. The Camelbak Better Bottle is BPA free, it holds one liter and it is tall and narrow which fits nicely in your backpack. I like the classic cap because the others with the spouts and tubes are just more to go wrong – and what can I say – I’m a purist, I go for simple and functional!

Towel, Swim Suit, Dry Clothes – With all the things mentioned above you should still have room for your personal items, especially if you go with the PADI backpack mentioned above.

SIDE POCKET 1 (LEFT OR RIGHT)

Pens, Pencils & Highlighters – I keep an assortment of each in a container in my side pocket. We often need multiple pens for the many waivers and releases needing signatures. Pencils are great for our underwater slates and accident management slate. Highlighters and markers come in handy too. I keep them all in a container if they leak then I have not ruined the inside of the pocket. Plus if they are in a container they are less likely to break from being bumped.

Calculator – Another great tool to have in your go-kit is a calculator. This is great when doing MOD calculations of gases, volume/pressure formulas, air consumption formulas, kick cycle formulas, etc. If I’m wet I do not want to use my phone’s calculator, I want a simple one that can get ruined and I won’t cry about it.

SIDE POCKET 2 (LEFT OR RIGHT)

Sunscreen – We don’t want to look like the Crypt-Keeper in our 40’s, so use sunscreen and lots of it!

Keys, wallet & phone – The side pocket is a good, accessible pocket for these items.

FRONT POCKET

Teaching Slates – I keep both the confined water and open water teaching slates for my agency in my go-kit. If I need to conduct a specialty dive or fill in for another instructor, they are always with me.

Accident Management Workslate – To me, this is a must have slate. Not only do I keep it in my go-kit, but I also keep one in my first aid kit and one in my oxygen kit. An Accident Management Slate is a wonderful thing to have to take down notes in the event of an incident, and anyone can fill it out.

Marine Life Identification Slates – I think the slate that has seen the most use over the years is my marine life identification slates. I used to have this in my gear bag, but it kept getting so scratched up and dented, that I put it in the front pocket of my go-kit and it has been great there.

Of course there are PLENTY of other things that could be added or included in your own kit. Dive locations, dive activities, weather, facilities used, etc. all play a part in what you keep in your go-kit. If you don’t have a go-kit start assembling it today, it will make your job as a dive pro a whole lot easier.

How to Get Your Sea Legs

By Tec Clark 1 Comment

Getting your Sea Legs can help prevent sea sickness

What are Sea Legs? And, can they help ward off seasickness? We will find out why this is an often overlooked, yet important skill to have when diving. Here we will describe the technique of getting your sea legs to assist with balance on dive boats and to help ward off seasickness.

What’s with the Name?
The term sea legs is a metaphor for adjusting to living, working or traveling at sea. Sometimes it is used to describe the imbalance one feels when coming back on land after being exposed to the motion at sea. But here we will describe the technique of getting your sea legs to assist with balance on dive boats and to help ward off sea sickness.

What’s Our Body Doing?
First, what is it that makes us off-balance and/or seasick to begin with? Well, consider that we are terrestrial beings. We live on land where gravity continuously meets with our laws of motion. Our bodies use multiple sensory stimuli to interpret and regulate our motion. Within our inner ear the semicircular canals are responsible for detecting motion of the body. The fluid in the semicircular canals combined with hair cells in the sacculus and utriculus transmit motion information to the brain. The brain interprets this input along with other sensory stimuli such as sight and touch. When there is disagreement between these stimuli (i.e. you’re sitting or holding onto something while rocking back and forth, or you’re staring at a non-moving object yet you are moving up and down) then you may experience loss of balance and/or seasickness.

The Technique
One of the best ways to minimize that disagreement of sensory stimuli is to minimize movement of the head. And how we do that on a dive boat is the basis for our sea legs technique:
1. Keep your head upright and straight. Every second of the waking day your body is making adjustments of how to keep the head upright – whether sitting, standing, walking, running, or riding a roller coaster. So, we are very conditioned to keep our head level. When we keep our head upright and straight, the horizontal plane of our ears and eyes is parallel (level) with the horizon. This prevents much movement in the semicircular canals. In fact, recent research from the University of Minnesota shows that the old sailors’ adage of “look at the horizon” actually has merit. The study concluded that looking at the horizon stabilizes one’s posture. Whereas looking at an object on a moving boat increased sway, thus increasing movement of the head.
2. Bend your knees and flex your legs to “ride” the wave motion. Like most sports, to keep a good center of gravity the legs must be slightly bent. This allows the legs to respond quickly and act like shock absorbers to keep the upper torso of the body stable and ready. On a moving boat, we want that same stability of the upper torso mostly because it will also keep the head from moving. Simply, bend and flex your legs with every motion of the boat. Doing this while keeping your head up and looking forward allows you to see the incoming waves and see the boat rise and fall. You want your legs to flex up and down as they ride each wave – again, keeping your head upright, level and as motionless as possible. In time, your body will sense the stimuli and make adjustments on its own. For instance a seasoned divemaster can work the back of a boat, not seeing the oncoming wave, but as the boat rises the signal sent through the feet as they begin to flex with a wave goes to the brain to make other postural adjustments to keep the body upright and balanced.

I hope you can now see why it makes seasickness worse to go into the head of a boat (motionless surroundings, while motion is occurring) or to lay down (head is not upright and straight). Note that this is a technique that needs time to be learned and that there are some who are chronically seasick whenever they go on a boat. In other words this does not work on everyone. And note too that if someone has been vomiting excessively, they may be too weak to stand up and keep balanced.

So next time you’re on the dive boat give this sea legs technique a try. Remember to focus on keeping your head still and your legs flexed. And finally, no matter how good your sea legs are, HOLD ON to solid objects for stability whenever you are on a moving boat!
1 Mayo, A.M., Wade, M.G., & Stoffregen, T.A. (2011). Postural effects of the horizon on land and at sea. Psychological Science, 22 (1), 118-24 doi: 10.1177/0956797610392927

How to Defog a Diving Mask

By Tec Clark 9 Comments

Why Does a Mask Fog?
First, what is happening when a mask “fogs”? Simply put the “fogging” effect you see on the inside of the mask is condensation. That condensation is present due to the water vapor in the air (humidity) meeting with the cooler glass (or plastic) lens and forming microscopic water droplets on the lens. This is similar to you pouring a tall glass of iced tea inside your kitchen. With our modern home air conditioning units our cool dry air conditioned house may have 40% to 60% humidity. When you look at your glass of tea, there may be a little condensation or wetness on the outside of the glass. But, as soon as you go outside (especially in a tropical environment), you’ll notice your glass looks like it’s sweating. Big water droplets appear, coalesce (join together) and run down the glass where a big water ring forms on the table. In this case, the temperature of the glass and contents did not change, but the outside air has now changed to about 80% to 90% humidity. So, the more water vapor in the air, the more condensation on the outside of the glass.

How these microscopic water droplets form inside a mask is factored by the surface tension on the lens, the humidity of the air inside the mask, and the temperature of the water. The use of a surfactant like commercial anti-fog or defogger solutions or even spit reduces the surface tension smoothing out the droplets on the lens. When condensation takes place on a surface that has surfactant applied it is less visible since the droplets coalesce creating a uniform moisture layer. That uniform moisture layer is easier to see through than the “fog” effect of microscopic water droplets.
So, what surfactants are available for de-fogging your mask? Well, there are a few considerations. But first we must understand the importance of “treating a mask” that is brand new prior to its first use.

How To Pre-Treat a Mask
First, many times when a diver experiences consistent mask fogging it is because there is something on the lens which enhances the fogging effect. This substance could be the original residue from the manufacturing process as seen with new masks, or it could be as simple as a little sunscreen was on ones finger when they applied defog to his or her mask. In these cases we need to “prep” or “pre-treat” the mask prior to its use. This is a special process, so to learn how to do it see my article and two-part video How to Pre-Treat a New Dive Mask.
Now, treating the mask won’t prevent your mask from fogging on each dive, so we have to defog our mask prior to each use. Here are a few methods.

Methods of Defogging a Mask
1. Commercial Defog Products – AKA “mask defog” is commercially available in just about every dive center. A couple products I have used and like are the McNett/AquaSeal Sea Gold® Defog and 500PSI® Mask Defogger. Priced each around $6-$10 dollars per bottle their value comes from how good and efficient they work. Both come in small two ounce sizes, and since small drops are used at time a two ounce bottle can last the typical diver quite a while with its advertised hundreds of applications per bottle. Plus, one application may last two to three dives. • Simply put one drop on the inside lens of a DRY mask and rub evenly with clean fingers (no sunscreen residue – sunscreen will remove the surfactant).
• Rinse briefly in either fresh or salt water.
• NOTE: DO NOT rub the lens or touch the lens during or after rinsing.
2. Spit – There’s nothing more fun than welling up a big one and planting it in your mask to be rubbed around! For some, this is downright disgusting. Whatever your take on the method, it actually works and remains one of the more common methods for defogging a mask. Saliva makes for an okay surfactant. It’s easy and cheap albeit gross. However, it does not last as long commercial defog products and usually needs to be applied just prior to every dive. The method of application is similar to the commercial defog:
• Simply work up some saliva in your mouth and spit on the inside lens of a DRY mask and rub evenly with clean fingers (no sunscreen residue– sunscreen will remove the surfactant).
• Rinse briefly in either fresh or salt water.
• NOTE: DO NOT rub the lens or touch the lens during or after rinsing.
A couple points worth noting about spit. 1. Some divers and dive professionals strongly discourage the spit method for defogging the mask. They claim that the high bacterial content in saliva is bad for eyes. But consider this, reports of eye infections associated with diving are rare. And, we have to remember that a slightly coated lens that has been rinsed simply does not have a high likelihood of getting into eyes – even when doing partial and full-flooded mask clears. Compare that to the plenty of waterborne bacteria in the ocean, lakes, freshwater springs and even swimming pools. Doing full-flooded mask clears or mask removal and replacement will expose the eyes to far greater amounts of bacteria, than that of the fine saliva coating on a mask lens. 2. Under NO circumstances should you spit in a mask and then rinse it in the rinse bucket of a dive boat! This is an almost certain way to spread viruses! The rinse bucket on a charter dive boat should be reserved exclusively for those using commercial defog or the dive boats’ preferred defog solutions. All it takes is one sick person spitting in a mask and briefly dunking it in the rinse bucket to contaminate the bucket.
3. Baby Shampoo – Here is a defog solution that is catching on in popularity. Baby shampoo is inexpensive, comes in travel size containers, is biodegradable, and won’t sting the eyes. It can be applied directly in small amounts or mixed with water and delivered through a spray bottle. Many charter boat operators are going with the spray bottle solution next to the rinse bucket. The steps, you guessed it, are pretty much the same as above:
• Simply dab or squirt the baby shampoo on the inside lens of a DRY mask and rub evenly with clean fingers (no sunscreen residue– sunscreen will remove the surfactant).
• Rinse briefly in either fresh or salt water.
• NOTE: DO NOT rub the lens or touch the lens during or after rinsing.  Be cautious of swishing the solution during the rinse and dumping it out on the deck of the boat. The soapy nature of the shampoo can create a very slippery deck.

Another NOTE: You may have noticed I keep saying use on a DRY lens. Go back to the first paragraph about surface tension and surfactants. If water is present on a lens before a surfactant is used, it will not work as well. Sometimes you notice just one or two spots on a lens is continuously fogging. Many times that is a result of defog or spit being applied to an already wet mask where water spots were already present. As an instructor trainer I often play a student during an instructor or divemaster class. I will intentionally wet my mask before putting whatever method of defog the instructor candidate tells me to use. Then, underwater my mask fogs over and over again totally confusing and frustrating the candidate. Ah… that’s good fun! Okay, in fairness I am also employing another instructor trainer problem solving challenge – exhaling through the nose increases the likelihood of mask fogging – which leads us to our final point.

Avoid Exhaling Through Your Nose – The air between your face and mask lens remains warm and moist. And with an occasional puff out your nose to equalize your mask as you descend, the airborne water vapor collects on the lens and disperses if there is a proper surfactant in place. But, if one were to continuously exhale through their nose, now there is a continuous supply of warmer and highly humid air. The stagnant air temperature warmed by the face is also cooled by the water temperature affecting the glass lens and the skirt. However, air that is exhaled from the lungs is substantially warmer and has a relative humidity of 100%. This means an ever increasing amount of condensation will form, eventually washing away inadequate surfactant like spit or inadequately applied surfactant. There are many reasons why divers exhale through their nose: a poor fit or leak lets water enter the mask and the diver regularly has to clear the mask by exhaling. Most divers do not efficiently clear their mask with just enough air to get the water out. Instead, it is a dramatic production complete with large exhalations of air into the mask. Another issue is for divers that have a sinus condition. Mucous production discomfort forces them to exhale into the mask. For others, a mask that is too tight is temporally relieved on face when exhaled air through the nose pushes the mask off the face ever so slightly. Another issue is overexertion, the harder a diver breathes the more likely for the nasal tracts to engage exhaling air into the mask. And, of course, we are all nose breathers primarily. For many, shutting off the nose breathing is difficult and they incorrectly inhale through their mouth and exhale through their nose. So focus just on inhalations and exhalations through the mouth only.

Whew… I know this was more information than you were expecting. But knowing why your mask is fogging will really help you understand what changes you need to make and what tools you can now use to prevent your mask from fogging.

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