“Don’t hold your breath” is a mantra heard in virtually every scuba diving course every taught. You can easily damage your body during ascention by holding your breath during SCUBA diving. The expansion of the air can quickly cause damage regions with very few nerve endings to tell you that you’re doing bad things to yourself. Today in SCUBA Theory, why breath holding is a valuable skill to practice.

SCUBA Theory: Holding your breath is a skill – Divester

I mentioned yesterday that I thought Divester was a site worth checking out. Their post on tips for kelp diving is exactly why. As someone who has done his good bit of diving in kelp, it’s not as scary nor as easy as it looks.

I normally surface swim face-up on my back. I learned that hard way that tank valves and lots of other equipment can get pretty snarled when you carelessly swim into a patch of kelp.

On the other hand, kelp dives usually have the most fish action so go give the Divester article a read and enjoy!

Excellent piece over at Divester on sharing air.

If a diver is hurting for air, they might start to panic. They’ll want the first regulator that they see and know has air: the one in your mouth. It’s a good idea to stay in control of your regulator. If a diver looks like they may need air, place your hand on your regulator. It’s better for you to hand it to them than have it yanked out of your mouth. You can make sure you grab a nice breath of air and demonstrate that you’re calm while handing it over. Someone who’s been swimming without an air supply will usually feel the need to catch their breath. If you just exhaled and a panicked diver grabs your regulator, you may not be very happy while they’re gobbling up air.

I’ve only had to share air once and it was in Cozumel on a vacation. We had done a deep dive in the morning but we had a fairly aggressive profile for our second dive. The DM suggested we do a good 5 min or more safety stop before surfacing which I felt was a pretty good idea. I’m not sure why but I became a little bored on the dive and decided to cut it short. I parterned my buddy up with another pair of divers and swam back to the anchor line where I did my extended safety stop. Near the end of my stop a pair of inexerpeinced divers (they were on their 4th post-certification dive) approached me on the safety line. My instructor instincts kicked in naturally and I glanced down at their pressure gagues and noted that both divers were in the red zone. I called them both close to me and held their guages up to their eye level so they could see that they were running low. Neither of them was going to make the 5 minute recommended safety stop at their current rate of consumption so I signaled to one of them that I was going to give her my octopus. She took it as the needle on her SPG started to approach 0 and I grabbed the waiststrap on the other diver’s BCD figuring I could share air with him if needed. I wanted to prevent panic and a shoot for the surface so I attempted to keep both divers calm by not appearing to be overly concerned about the situation.

As the second diver’s SPG approached zero I noted that the DM was leading a group up the line. I gave the line a few good yanks to grab his attention and he swam up. I showed him the two SPG’s and he gave the second diver his octo. I had noted the time when the other two divers had approached me so I knew when they had had a good 5 minutes of off-gassing. When we hit the 5 minute mark I signaled to everyone that we were going to make a nice, easy ascent and we got everyone on the surface.

My first (and hopefully last) air sharing experience went rather calmly. I don’t think either diver realized in how much danger they were in. I’m quite sure the situation would have turned out very differently had they taken a hit and they couldn’t draw any air.

As an instructor, I always knew that I shouldered a special risk. You are in charge of a group of people who do not know how to dive yet. As long as you can lead them they should be fine but what if something should happen to you? I’ve always felt like being on a teaching dive was like being a solo diver. I don’t really have a buddy who I can count on to react calmly to the situation.

I’ve experimented around with carrying a pony bottle and having three air source (reg, octo, and BC octo) but in analyzing the situation I’ve come to the realization that in an emergency, as an instructor diving with inexperienced divers, the first thing they are likely to go for is the reg that’s in my mouth. That leaves me without an air source and attempting to help a diver at some level of panic. I don’t have time to waste in finding my octo so the normal placement affixed to the BC shoulder strap doesn’t seem optimal. The octo could easily become dislodged during a dive without my knowledge and then I’m wasting time sweeping behind me trying to find an air source.

The solution I like best is the DIR-inspired necklace. It keeps the octo near your mouth and it’s much more noticable when it becomes dislodged. I’ve practiced with it and can actually get the octo in my mouth without using my hands. It’s much cleaner to use my hands but it can be done simply by dipping one’s neck.

Fortunately, I haven’t had to test this configuration out in a real incident but I do make sure to communicate the location of my octo to my buddy and students when I dive. If anything, I think the unusual placement sticks out in people’s heads and I’ve gotten quite a few “That’s not a half bad idea,” from other divers.

A good article on how to maintain your regulator and other misc. hoses.

Here’s an email sent to me the other day by Larry:

Even when I dive to the bottom of a swimming pool, I get pain in my ear. Is this common and how can it be prevented?

Hi Larry,

The pain you describe is caused because the pressure outside of your ears is different from the pressure inside the air spaces in your ear. If you do not equalize the inside and outside pressures you can do serious damage to your ears. Many people experience a similar discomfort when flying as a result of the differential between the air pressure shifts at various altitudes (usually takeoff and landings). For aircraft related discomfort it is usually recommended that you chew gum or yawn in order to “pop” your ears. Diving works the same way however I wouldn’t suggest chewing gum or yawning during a dive What yawning and chewing gum do is promote the opening up of the eustachian tube which allows the for the pressure equalization between the outside air pressure (or atmospheric pressure) and the internal pressure.

The eustachian tube is small opening that connects the pharynx and the middle ear. While going into a lot of physiology might be more than what you want to know, let’s just say that this tube or opening connects your middle ear with the outside pressure which equalizes the air inside of your middle ear with the pressure outside of your middle ear.

As I mentioned, you might want to avoid chewing gum or yawning while diving so the trick is to re-create the same effect which is opening up of the eustachian tube. Most divers do this by pinching their nose and gently attempting to blow out through the nostrils. Mind you, I said gently. It is not to be done forcefully otherwise you may do damage to your ears. A gentle blow will usually open the eustachian tube quite nicely. Other divers prefer to wiggle their jaws or to form an “O” with their tongue in their mouth which all induce the same response.

Sometimes if you have a cold or other physical response that causes either swelling or blockage it will be difficult or impossible to open up the eustachian tube to equalize the pressure. The only recourse is to abort the dive. I have yet to encounter any dive worthy of losing my hearing or doing other permanent damage to myself. The ears also control your equilibrium (balance) so you could end up stumbling around like a drunk the rest of your life if you damage your ears too.

All of the PADI entry level diving courses contain information air space equalization and it’s something you practice from your very first dive in the pool.

Bill

As an instructor who teaches underwater navigational skills and someone who reads more than his fair share of scuba industry related publications (and websites, and message boards, etc.) I’m always a little surprised that I rarely see mentioned what I consider to be one of the more useful tricks of the trade so I thought I would share it here.

First off, let me start off by admitting that I’ve gotten lost before. In fact, when I first started diving it used to drive me crazy when I surfaced where I thought the boat was and I was waaaaaaaaaay wrong. Partly because I consider myself to be a tad of a land navigation expert. When I served in the Army part of my job was to evacuate injured troops with my only way of finding them being a set of grid coordinates, a map, and a compass. I’ve even set up and helped judge night land navigation competitions so this underwater thing should be no problem, right?

Well, that’s what I thought. See, on land you have a couple of things working in your favor:

1. Visibility

2. The ability to travel in straight lines.

Underwater visibility can make navigation tricky. You probably have better visibility on a well lit evening than you do in 30 foot viz on a mediocre diving day.

And this is the key to the tip I promised; underwater it’s difficult to travel in straight lines. Sure, you can travel along a compass bearing but you’re only on track for as long as you’re staring at your compass. Since most of us dive to enjoy the scenery there’s a pretty good chance we’re going to take our eyes off the compass now and again during the dive with anything from surge to current to just plain mentally zoning making you swimming off course until you check your compass again.

So let’s say you do a simple out and back pattern. You swim out for some predetermined amount of time or air supply and then you double back on the reciprical compass heading. If you’re off on your compass bearings 30% of the time (which is being pretty liberal) you’re 30% off on the way out and 30% off on the way back. Depending on the conditions that put you off course that could mean the difference between surfacing right under the boat and being a couple of hundred yards from it.

So how do you keep on track? Well, in the Army you shot a compass bearing and then you picked out a land feature that was dead on your compass bearing and when you got to that land feature you took another compass heading and lined up another land feature.

The same can be done underwater. Instead of following your compass the entire dive just shoot a heading and then look for something very specific on that heading. It could be a rock, the opening in a kelp bed, or anything else that isn’t likely to move between the time you take a compass heading and the time you reach it. Once you’ve got that feature picked out you can zig zag all over the place, do flips or anything else you want between point A (where you started) and point B (the point on your compass heading) because you can see where you need to go. Once you’re there, take another compass heading and keep going.

Obviously you would do the same thing on the way back but once you start getting good at it you’ll be able to pick many of the same points on the way back in as you did on the way out so if you remember that on the way out you swam from the rock to the old tire, on the way back when you get to the old tire you may not even need to take a compass heading if you can see the rock and know that that’s your next navigation feature.

It’s pretty simple once you get the hang of it. Give it a try on your next dive.

In August edition of Rodale’s ScubaDiving they quote a survey in which 25% of the people polled admitted to jumping in the water, at least once, without turning their air on.

I can only guess the same rule of thumb that applies to peeing in your wetsuit is going on here:

50% of divers admit to peeing in their wetsuits. The other 50% lie about it.

I’ve never quite made it into the water forgetting to turn my air on (thanks to some thoughtful divemasters and the fact that I make it a habit to take a few breaths off the reg before I enter the water) but I’ve had a few buddies (and other instructors) swim up to me and sheepishly ask if I could turn their air on for them.

Despite this perfect record (chuckle), my worst mental lapse was when I got to the gate to exit the boat and the divemaster just looked at me. I put my reg in my mouth as I asked “What?” and she replied “You’re not going in like that are you?” I did a quick pat down of my gear thinking I might be twisted up or something and upon finding everything in it’s place I said “Sure, why?” “Well, unless you’re going to go running along the bottom you’re probably going to need your fins,” she replied. Lucky for me I was one of the last divers off the boat so that incident stayed our little secret.

Last weekend while I was diving with a buddy we got to where we were going to exit and I looked down at my computer which was indicating that I had already surfaced from the dive and that I was enjoying a surface interval. Now, as I was a good 20 – 30 feet below the surface I was pretty sure I wasn’t at the surface so I punched a bunch of buttons on the computer thinking it might come to its senses.

It was only then that I noticed that the battery meter was registering in the “need to be replaced mode.” The funny thing is that for the last several years I’ve carried a backup computer somehwere on me just in case but almost felt foolish for doing so. Not this time though. I reached in my drysuit pocket and my backup was working perfectly.

I had remembered what my now impared computer had said was my maximum depth during the dive (and had a general sense for the total dive time) and compared that to the backup and they seemed to match so it was a relief that I hadn’t been getting faulty readings and had been diving much deeper than I had thought I was but still an eye-opener that just because a computer goes into dive mode on descent doesn’t mean that it’s got enough juice to see you through the entire dive.

So the lessons learned here are:

a) Check your computer’s batteries every couple of years or so.

b) It’s always good to have a backup.

On a side note (that I almost feel foolish admitting); on my backup computer it has a voltage reading. If it goes below 2.8 I know to replace it. On my primary computer it has a bar graph that displays when you first begin your dive. I always check the voltage numbers on the backup and replace at 2.8 even though it could probably go all the way down to 2.0 before it becomes an issue. On my primary, I don’t think I ever really checked it because it only displayed for a few seconds when going into dive mode at the beginning of the dive. That’s a mistake I won’t make twice

An interesting little story on spearfishing from depths of 200 feet or more.

Jo asks:

Hello Bill, I am in a scuba class and am finding that I am not as comfortable in the water as I thought as I would be and find myself with mini-anxiety attacks. I’m not used to being underwater and I would really like to work on this challenge and am wondering if you could provide me with any breathing tips, or any other tips that will allow me to be more comfortable in the water.

Overcoming scuba anxieties,

Jo

Answer:

Hi Jo,

Hmmmm . . . . I don’t know if I have any “breathing tips” per se but I would highly recommend getting in more pool time. As you’ve said, you’re not used to being underwater (none of us are when we first begin scuba) so you should get used to being underwater by being underwater. I’m quite familiar with the mini-anxiety attacks you mention and as long as they are only “mini” attacks they will probably go away the more accustomed you become to being underwater.

Your objective should be to relax. Any breathing style that helps you get relaxed will help but normally the longer and slower the inhalations and exhalations the more relaxed you’ll become. Some people say that focusing on another part of the experience helps. For instance, many people get a little claustrophobic from being underwater so if you focus instead on the sensation of the cool water against your face you will be shifting the focus of your attention. If you really feel that this is going to be a problem you might want to schedule a date with your instructor for additional pool sessions. Of course, that brings up an important safety point which is to do all of this under the supervision of your instructor. Do not attempt to jump in your pool at home and work on it. It’s simply not worth the risk.

I also recommend that for people who have any sort of anxiety about diving that they always arrive for their classes early. If you’re there early you have time to think, relax, and take your time. If you’re wheeling into the parking lot 5 minutes after the pool session was supposed to begin you’re going to be very hard to relax and you’re more likely to make mistakes as you rush to catch up with the rest of the class. On the boat, get your gear and everything set up when you get on the boat. If you stay one step ahead of everything you won’t feel rushed and you’ll be able to relax much easier in the water.

One of the things I’ve always found funny in a way is that scuba diving can be one of the most relaxing things you can do. You are floating weightless being treated to an amazing show put on by Mother Nature. Your heart rate and your breathing fall into a smooth, steady, slow rhythm. It’s almost like meditation. The funny part is that for many people just learning to dive it is anything but relaxing. They see nothing on the dives because of the adrenaline rush going on inside them. Instead of relaxing their breathing and heart rate shoot up as they deal with all of the anxieties of this new environment. But those who stick with it are well rewarded.

Please let me know if I can be of any other help.

Bill