In One Way, Depth is Just a Number...

(I started writing this post back in 2010, came across it, and decided to revive it. As of 2013, I'm a Rescue diver, albeit I do need to go back to Lake Ellerton and practice fishing people out of the water some time soon. Funny how even back then I was picking holes in PADI's teaching methods...). 

And in others, it isn't.

As part of my Advanced Open Water Certificate, I'll be doing a "deep dive" whilst in Bute for the diving weekend I'm going on in March. For those not familiar with recreational diving limits, I currently have an Open Water certificate, which means I'm qualified to dive as deep as 18 metres.

In common with (I suspect) most Open Water divers, I have somewhat bent this rule - without getting myself bent, I hasten to add - whilst diving in the tropics. My deepest dive so far was 23 metres in the Maldives to see an interesting sunken ship. It was at the start of the dive, myself and my buddy had full tanks, I wasn't tired or dehydrated and I kept a close eye on my dive computer and air gauge, so I figured I wasn't running an unacceptably high risk of burning through my breathing gas or running out of bottom time. I was right.

A quick digression on some terms I'm using here:

Bent = getting the bends; decompression sickness causing by ascending too fast or staying down so long you can't come straight up but have to do decompression stops. Recreational or sports divers, like me and like everyone when they first start diving, do the sort of dives which don't require decompression stops, so that at any point in the dive, you can abort it and ascend to the surface, albeit at a slow enough rate that you don't get the bends. This is for safety reasons.

Bottom time = the amount of time you can stay submerged before you have to ascend. Governed by two factors; how much breathing gas you have, and how much nitrogen you have absorbed from breathing gas under pressure. The amount of nitrogen you have absorbed governs how long you can stay under without needing to do decompression stops to allow the nitrogen to leave your system so that you don't get the bends. The two factors are interlinked: If you're at a deeper dive, you go through your breathing gas faster, because it is delivered at a higher pressure. This also means you're breathing in more nitrogen molecules - it's a compressed gas, so there are more gas molecules in each breath you take in - so you absorb more nitrogen and have a shorter period of time you can safely stay under. Also one of many diving terms that causes juvenile humour to occur. 

For my "deep dive", I'll be going deeper than this. It's surprisingly hard to find out exactly how deep online - it's something I'll ask my instructor - but probably around 25-30 metres deep depending on the conditions.

This post starts "In one way" because a novice diver saying "depth is just a number" and leaving it at that implies that person hasn't fully grasped that deeper dives do come with a set of distinct challenges. These include the aforementioned shorter bottom time periods and the fact that they use gas a lot faster than shallower dives. They also include the unique aspect of getting the narcs.

The narcs = nitrogen narcosis. Essentially, the deeper you go, the more the higher concentration of nitrogen you're breathing makes you feel intoxicated. It's most commonly compared to being drunk, although symptoms vary from diver to diver. The narcs are harmless in themselves and go away if you ascend (safely) to a higher depth. The risk comes from feeling a bit drunk 30m below the water. It's even worse for technical divers, who have to fiddle around with their gases to try to come up with a mix that won't send them completely off their heads whilst 60m down.

But in one way, I believe that depth is just a number. Why? To me, it's in the mind. One thing I think PADI's Open Water Diver course does run the risk of is encouraging newbie divers to think "It's okay if things go wrong, I can always go back up again". I think that's the wrong mindset. Sure, there are times when a CESA (controlled emergency swimming ascent - swimming up to the surface if you've run out of air, but keeping your weight belt on so that you don't rocket up there, and exhaling to stop you from getting lung overexpansion injuries) or even the dreaded buoyant ascent are the right, i.e. only, options to handle the situation.

Buoyant ascent = ditching your weights so that you immediately become positively buoyant and fly up to the surface in an uncontrolled ascent. Extremely dangerous as you run the risk of getting lung overexpansion and the bends. Absolute last-ditch measure for getting to the top if all other hope is lost. Comes with a big AVOID DOING THIS IF YOU POSSIBLY CAN in the diving training manuals.

However, I think that's a risky mindset. It encourages you to think that all problems are solvable and there's always a way out, whereas you should be thinking about how to prevent the problems in the first place. You can get the bends coming up from 12m or even shallower. Going deeper increases the risks, but the risk is always there.

Dive safely, folks. And remember... in British waters, there's frequently bugger-all to see at 30m in March in the Farne Islands. 15m is more fun, and there are seals!

Still Writing My Post

I've been spending the week trying to write a post about "The Olympic Spirit", which is actually an article I want to put in my church newsletter. This has been somewhat held up by office moves, house moves (I hope - haven't yet exchanged contracts!), and my in retrospect poor decision to slug five glasses of wine last night in Perdu. Actually, I don't regret that last one. Screw it!

To hold you between now and then, here's a picture of an unexploded WWII bomb under the water, which I saw in Crete. More actual writing coming soon.

Things You Don't Want To Hear Upon Surfacing At The Dive Boat, I

Which would be, as I surfaced from my dive, "The engine's conked out. Steve, get the rod... we're drifting a bit close to those rocks."

Oh, and I realised a vital piece of my equipment might one day kill me.

Winding the tape back. Yesterday I went on a boat dive to the Farne Islands. The Farne Islands are one of the North-East's, and probably the whole of the UK's best dive sites. A set of small rocky islands off the Northumberland coast, they are home to a wide variety of fish, a lot of lobsters and, most importantly, a colony of very friendly and inquisitive grey seals. Videos of divers playing with seals at the Farnes are common on Youtube, and I should add that the seals themselves like to come up and play. They are especially fond of nibbling divers' fins. I know one diver who said that, during one of his dives out there, he seemed to keep kicking his buddy in the face. No matter how hard he tried to move position to avoid it, it kept happening. Finally he turned around, and saw that a grey seal was thoughtfully chewing his fins.

As we arrived at the Farnes aboard our RIB*, the seals popped their heads up to see who was coming to play. I was doing my Deep Diver dives 2 and 3, down to 25 metres. Not my deepest ever dive - that was the 32m dive at Stoney Cove - but the deepest I've been in the sea.

We fell over the side of the boat, demonstrating the "backwards roll entry" which everyone has seen divers do, with varying degrees of proficiently. I kicked over fast to join my colleagues, who of whom suffered from seasickness and had seen his colour dramatically improve since he got off the boat and into the water. He was my buddy, and, accompanied by our instructor, J, we headed off to explore the rocks and grab some depth.

This was one of the best dives I've ever had in the UK. At least 15m vis, bright sunny weather, no serious currents or surge, and lots and lots of fish and lobsters. I tried out my new torch, marvelling at how it really did make it easier to see things even at shallow depths. We finned along, looking at lobsters and occasionally pausing to admire a passing seal, whose turn of speed we could only wish for!

We did our Deep Diver task; a straightforward out-and-back compass navigation swim on the bottom, worked our way up the wall, did a three-minute safety stop hanging onto the kelp, and surfaced, to be met with the words above.

The next hour and a half was spent drifting about as the owner tried to keep us safely anchored whilst trying to obtain a spare anchor from a nearby boat (I really hoped at one point he wasn't going to throw it into our boat) and fix the loose connection in the engine. This did NOTHING for the seasick among us, and all in all we were very relieved to hear the engine start up again!

We motored over to the buoy marking "the boilers", part of a wrecked old ship, and the site of our second dive. And as I descended down the line (wondering why the hell I could see a bathtub down there), I felt the exceptionally unwelcome sensation of my weight belt slipping around my waist. The wretched buckle had slipped along the belt, meaning that the buckle itself was now stuck under my jacket at the side, and my buddy wouldn't be able to find it in case of an emergency. I doubted it would come off, but... should I abort the dive?

I didn't, though I'm still not sure I made the right call there. If I had - no second dive. On the other hand, if my buddy had needed to get it off me, or it had slipped off completely... I did the dive holding the belt with one hand, which wasn't ideal, but did work. It didn't actually come off, but it was a severe nuisance, and I made a mental note that, first thing tomorrow, I was going to Ebay myself a new weight belt. (I did, and have it now.) A weight belt that won't release fast is technically known as a potentially fatal accident waiting to happen.

On the other hand, I still had my weight belt. J was the last one in, and we heard the following conversation:

"Pass us your weight belt, J... pass us your weight belt. Pass us your weight belt... you've dropped it, haven't you?"

He had, so our return home was slightly delayed as we fitted J with spare weights, and he went down there to look for it. (Senior instructors are able to dive alone safely, if they assess that it's safe to do so - the rest of us stick to diving in pairs.) One retrieved weight belt later, and we were hanging onto the boat, and heading for home! All in all, a great day.

*Rigid Inflatable Boat - popular for diving as they are fast, maneouvrable, and extremely hard to capsize.

"I Had Air Coming Out Of My Eyes" (Boat Dive)

Is not a sentence, thankfully, that one hears very often.

Let me backtrack a little.

I did my first boat dive in the UK last Sunday, off Eyemouth, just over the Scottish Border. It was the first club boat dive in the UK for the season*. Our Chief Instructor introduced the first dive with words along the lines of "this is the first boat dive of the season, let's be careful whilst everyone gets used to doing this again and be prepared for things to go wrong".

He was right.

It's fair to say that I'm at that stage of experience (22 dives as of last Sunday) where, despite my shiny new card saying "Advanced Open Water", I still begin each dive wondering what I will manage to do wrong this time. I'm not a particularly awful diver (I like to think), but diving is complex enough that until everything becomes second nature, there's usually so many things going on at once that I manage to get one of them wrong. Fortunately, my training was good enough that it's usually the smaller things like "forget to put fins on before scuba unit**" on the boat rather than the really important stuff like "check all the connections are in place, the air valve is turned on and the jacket is inflated BEFORE going in the water".

It's easier to put your fins on first on a boat, since it's more difficult to bend down and tighten them with the scuba unit on your back. On a shore dive, the fins only go on once you're about to go in the water, since it's nearly impossible to walk over rocks wearing fins. One of many things I learned last Sunday.

I really enjoyed the dives, but the same cannot be said of us all. Our tally of mishaps included:

a) A diver in the first group surfacing a minute or so after the group had started to descend with the memorable words that form the title of this post, preceded by "I can't equalise". Being unable to equalise your ears and sinuses*** is a situation all divers dread, as it makes diving impossible and means you've had a wasted trip. It's usually caused, as it was here, by having recently had a cold and having blocked sinuses, making it impossible to push air up the sinuses and equalise the pressure on the inside of the ear drum. He had tried repeatedly to do this, apparently so hard that the air had leaked out of his eyes via the tear ducts. I had not previously known this was possible.

b) One diver with a flooded mask and regulator knocked out of her mouth at the same time. An awful situation to be in, since you lose your ability to breathe and to see at the same time. We do, however, train for this; regulator recovery and mask clearing are among the first skills every diver learns before you are passed fit to dive. Doing them in training is very different to doing them unexpectedly in a real situation, and I was most impressed by how calmly she told us this afterwards. (Didn't want to go back in again afterwards though - I'm not sure I would have wanted to either.)

c) One diver with severe seasickness. Apparently the cure for this on a dive boat is to have them jump back in the sea and swim about - it's not too cold to do this if you're wearing a full 7mm semidry suit with hood, boots and gloves. I didn't know this, either, but unfortunately it failed to work. If you try this, you have to avoid it coinciding with another diver deciding to use the "other head". The "head" on a boat is the toilet to landlubbers, and the "other head" is "off the back of the boat", if you happen to be male. Getting an eyeful of pee, or even just an eyeful of peeing diver, isn't going to do anything for the sickness.

d) Two divers deciding after the first dive that one was enough for the day. It was a very cold first dive, and any diver can decide to stop diving for any reason - not feeling happy on the dive is all the reason you need.

e) One diver with a snapped fin. He must have caught it stepping off the back of the boat into the sea. It split nearly in half, hanging on by the barest thread. I was swimming behind him on the dive, and spent at least ten minutes thinking "is it going to snap, will we be towing him back to the boat, is it going to snap now, will we be towing him..." etc.


Other than that, it was a good trip - for me, anyway. I hadn't done a boat dive in the UK, and part of the reason for my wanting my shiny new Advanced Open Water card was to be allowed on the boat - the skipper of the boat we were diving from insists that all divers must be AOW to be allowed on. One difference between it and the Maldives was that this boat had a boat lift, essentially a small platform that descends from the back of the boat far enough into the sea for a diver in the water to stand on. The platform then rises so that you don't have to climb back onto the boat - it lifts you up. Neat! And very practical. I was fine climbing out of the boat in the Maldives, but trying to do so in a full 7mm semidry suit with 8 kilos of weight round your waist at the end of a dive would be a different kettle of fish.

I got two dives in. I have to say that the first one wasn't awful, but I wouldn't quite class it as fun. I was a bit nervous on the descent, mainly because as I descended further I realised my weight belt was a bit too loose - I must have failed to cinch it tight enough on the boat. This was not a good situation. Aside from making it harder to swim, having your weight belt come off is risky. Losing 8 kilos of weight is a sudden enough buoyancy change that you would risk an unplanned buoyant ascent, which can give you DCI****.

I considered trying to tighten the belt, and decided to leave well alone, reasoning that although the belt wasn't tight enough, the buckle itself was firmly fastened, and the belt wasn't loose enough to slip over my hips when I stood up on the boat or when I was swimming. I weighed up "slightly loose weight belt which is staying on" versus "possibility of losing it altogether if I undo the fastening" and decided to leave well alone.

Probably I should have gone for the third option, "ask buddy for help". That I didn't is no reflection on him, but rather a reflection on my own feeling that I wouldn't have been able to signal clearly enough what I wanted him to do, and also signal the other divers in the group to slow down and stay with us. I made it to the end of the dive with the weight belt firmly in place, and learned a valuable lesson about the importance of donning the belt properly. Second dive = no problems with belt!

As a consequence of this and of the fact that during the descent I couldn't seem to find the inflator hose for my buoyancy jacket (it sits on my left shoulder, and I'd probably have been able to find it easily if I hadn't been so distracted), I was sucking air pretty fast. When we got down there, I remember thinking "I am breathing WAY too fast, calm down, calm down, breathe slow". I calmed down, breathed slow, and followed everyone else along a most impressive reef dive. Not much fish life, but many anemones and sea urchins, very striking to look at. We swam through fields of kelp and hung on to it to keep ourselves stable during a safety stop***** (another trick I learned last Sunday).

Most of that first dive was uneventful, but cold. It was 15m deep, which is plenty deep enough in British waters in April without a drysuit. I am seriously beginning to hear the call of the drysuit. I hate to be cold more than anything else, and whilst on a dive I can usually put my feelings about being cold "in a box" and focus on something else, after about half an hour the dive ceases being fun. Unfortunately, the dry suit plus the undergarments plus the training to use it safely costs a pretty penny or two, so I'll be diving wet for a while. Not that the manufacturers of my semidry suit fell down on the job; when I peeled it off for a quick pee, my body was sufficiently warm that water vapour was rising off me. It's just that everyone's tolerance for cold differs. Ah well, one of these days...

I settled myself inside the boat, bundled myself in a jacket, drank some coffee and ate a chocolate mini roll. Ah, the joy of diving; the perfect excuse to eat whatever you like... Shortly afterwards I headed back out again to get some fresh air. Sitting inside the cabin was like being in a small box being violently shaken by a giant, and I was not feeling so great. Some fresh air, and I was fine.

As ever, I had to nerve myself a bit to go back in for the second dive - the little voice in my head was going "You want to go BACK in there where it's all cold?" - but I had paid my money, and wanted to dive.

I'll admit, there was a stupid pride thing going on too. I was going to be the only female diving with the second group, and, if I'm really honest, part of me wanted to show that I can do two dives, just like the men. Which is a stupid reason to dive, I know. Nobody on that boat is sexist, or would seriously question that... it's all in my head, I know. But, more importantly, I really, really, wanted to dive.

The second dive was shallower (second dives always are) and over "the boilers". These are bits of a wrecked ship, which have been down there so long they don't resemble a ship, but you can see which bit used to be the boiler. I got back in there, and the second dive went much better. No problems with weight belt, no problems with buoyancy hose, ears equalised just fine, buoyancy control was nice and smooth. Only thing I got wrong was ascending a little too fast at the end (my computer beeped at me), but I don't seem to have suffered any damage as a result.

It was a good dive, nice visibility, lots of interesting wreckage to look at and I think I saw a fish. Most of all, there was the joy of being underwater in a pack of divers. When diving goes well, when your ears are clear and you hover weightless in the water with neutral buoyancy, powerful fins propelling you easily through the water, swimming in a team with your fellow divers... there really is no feeling like it. I'm trying to describe it, but my words really aren't doing it justice.

It was a good day. Accidents, seasickness and air coming out of tear ducts notwithstanding.

* The UK diving season runs roughly in line with British Summer Time i.e. around April-October. It's not to do with the clocks going back or forwards, just that this is roughly when the water is warm enough and the weather good enough to make diving feasible for the majority of recreational divers. It's certainly possible to dive in colder conditions, but this generally requires more gear and a generally higher level of complexity. For the majority of recreational divers wanting to dive in the UK, April-October is the main "dive season".

** scuba unit: the inflatable buoyant jacket, air tank ("bottle") and regulators to breathe through. The bottle is strapped onto the jacket, the regulator's valve screws on the top of the bottle, the jacket's air hose is connected to the bottle with the low-pressure inflator connection, and you put the whole thing on like a sleeveless jacket.

*** equalising your ears; as a diver descends, the increased water pressure puts the ear drum under strain due to the lower pressure on the other side of the ear drum, just like when you descend in an aeroplane whilst flying. The solution is the same, too; you pinch your nose, then blow against it gently to push more air into the sinuses and air passages within the ear, thus equalising the pressure on both sides of the ear drum and reliving any discomfort. Simple to do, but absolutely vital. If not done in time, you can damage your ears badly.

**** DCI = Decompression Illness. Term referring to someone showing symptoms that could be caused by either the bends, a lung overexpansion injury (where you have come up too fast and the air in your lungs has expanded at a rate that has damaged them - ascending at a safe rate avoids this) or, if you're really unlucky, both. Decompression sickness (DCS) refers specifically to the bends.

***** Three-minute stop at five metres' depth. Recreational divers plan their dives to avoid having to do decompression stops, for reasons I'll rabbit on about in a later post. We do, however, do safety stops, which are not mandatory (unless you've been diving deeper than about 30 metres - even then, you still theoretically shouldn't need them, but you would do them to avoid risking the bends), but considered advisable to minimise any risk of getting the bends. Especially prudent on a cold dive where divers work harder and consequentially breathe a larger volume of air, thus loading more dissolved nitrogen into your body tissues.

Got My Advanced Open Water

I headed off to Bute for a weekend of diving and exploring the strange and eccentric (but charming) pubs of Rothesay. I'll be cycling there this summer, so pub research was important.

It was great fun but cold. One of our trainee divemasters has just acquired a drysuit. We have had to open the equivalent of a swearbox where every time she says "drysuit" or "warm", she has to put in 20p.

It was somewhat cold in Bute.

6 degree C water temp, which feels as cold as it sounds. I have to say that I tip my hat to the manufacturers of my semidry suit*, which did its thing with remarkable insulating properties. Even so, I can reeeally see the appeal of a drysuit. Though, at around £400-£600 for the suit plus the undersuit plus the training to use it safely this might be a while coming for me.

I did the standard deep and navigation dives, plus a night dive, peak performance buoyancy dive and underwater photography dive. Great fun! The navigation dive was interesting because the visibility was AWFUL - it really was a case of "follow that compass"! Never have I been so glad to see the bright green fin of Singing Chief Instructor the... chief instructor. (Single fin. His other one is black so that he can't get mixed up with anyone else. Singing Chief Instructor, henceforth known as SCI because I can't be bothered to keep typing it out, is awesome.)

Interestingly enough, the deep dive was not my deepest dive ever, at 21m. That was a 23m dive I logged in the Maldives. Let me assure you that if you're thinking "23m in warm clear tropical water is way different to 21m in dark, murky, cold British waters", you are entirely right. Depth does not scare me in itself, but it was cold. It's traditional to make a diver on their first deep dive perform a task at depth such as writing their name and address on an underwater slate. This is so that you can see the slowing-down effects of nitrogen narcosis ("the narcs"**) at depth. By the end of it I was thinking "I really hope SCI doesn't make me write my name on the slate - so far no nitrogen narcosis, but my fingers have stopped working".

More on the other dives and the entertaining pubs of Bute shortly. Also probably some photos of crabs.

But, YAY, for being back diving! Yes!


* Semidry suit. Essentially a very thick wetsuit with a certain amount of marketing guff attached. Basically it keeps you warm like a wet suit, by trapping water next to your body, which heats up. A semidry, unlike a normal wet suit, has rubber seals at the neck, wrists and ankles, so that the warm water stays in and doesn't wash in and out of the suit. Surprisingly comfortable if fitted properly. Also they make you feel like a superhero in your brightly-coloured skintight suit, as you pull it on and fasten up your black boots, ready for your next adventure...

This is somewhat spoiled by the fact that you have to strategically plan a pee ten minutes in advance.


** The narcs = "nitrogen narcosis", caused by breathing air (which has nitrogen in, as we all know) under pressure at depth. No-one quite knows how it happens. Essentially the deeper you go, the more thick-headed you can become, like being drunk. This can be a major problem if you need to react quickly to a problem. It is, fortunately, relatively easy to solve - you ascend slowly until the symptoms resolve - and doesn't leave permanent effects. Not to be confused with the bends, on which more shortly.

Rocket Guy

Well, just over a week ago I did a refresher dive in Benfield pool, and thankfully it turned out not to be a case of "all mouth and no wetsuit". We practised standard skills: mask removal and clearing, taking the scuba unit (BCD+, tank and regs) off*, breathing from a free-flowing regulator++, hovering, fin pivot, and CESA**.

I was slightly dreading the mask removal. This is the one skill that a lot of divers HATE having to do on their training dives, although some say they don't mind it. No-one likes losing their vision under water, and getting cold water straight in your face (I did my training dives in the Firth of Clyde off the west Scottish coast) is no-one's idea of a fun time. It is, however, essential to master since it's not completely unknown to have a mask strap break, or a mask knocked off whilst diving. I was actually quite relieved when the instructor indicated we'd do that first, and pointed at me to go first. I took one breath, then pulled the mask off and shut my eyes.

My first thought was "Damn, I hate breathing through a regulator without having my nose covered by the mask" (diving masks cover your nose). It sounds daft, but the bubbles go right up your nose and it's no fun. I breathed maskless for a minute. This is also a skill, since if you lost your mask completely on a dive you'd have to be able to breathe through the reg without it until you made it safetly up to the surface. I then pressed the mask back on my face, slid the strap over the back of my head, tipped my head back a little and held the top of the mask against my forehead with the palm of my hand. Breathe in, blow out smoothly through nose, let the air force the water out and... open eyes.

I looked out through a perfectly-cleared mask, and had to resist the urge to do the Underwater Victory Dance. (There wasn't enough room - it's a small pool.) Go, me!

Here is a video of a PADI Course Director doing this with much more grace than me:








We next practised buoyancy skills. A skilled diver can sit on the bottom of the pool, inflate their buoyancy jacket just enough to rise off the bottom as they breathe in, then hover almost motionless in the water, controlling their buoyancy as they breathe in and out.

I'd like to think I'm a skilled diver. Unfortunately, I was wearing my own fins, meaning that I was wearing my neoprene diving boots. (I have open-heel fins which fasten with a strap at the back to allow you to wear boots underneath them, meaning that you have to wear the boots, otherwise the fins don't fit.) Neoprene is buoyant in water, meaning that my feet are more buoyant than the rest of me. I can hover in the water, but, alas, only in a position where I'm on my back with my feet floating above me, like an upturned and possibly dying turtle. Hilariously funny for anyone watching. Next time I do this I'm going to try wearing little weights around my ankles, and see if this fixes the problem.

At least I was doing better than Rocket Guy. I probably shouldn't call him that, but it's hard to resist. He was one of the other refresher students, and could not seem to quite grasp the concept of "you put SMALL amounts of air in your jacket, because BIG amounts of air will make you so buoyant you float to the top", despite the instructor's increasingly insistent hand signals. Ah well. After he'd gone from the pool bottom to the surface a few times he seemed to get it.

Towards the end, we practised our CESAs (see below). CESA is meant to be done on one lungful of air, since that's what you'd have in a real OOA (out-of-air) emergency. You swim from one side of the pool to the other, beneath the water, keeping the regulator in your mouth and exhaling as you go.

Rocket Guy didn't seem to get this, either. We know this because, when you exhale underwater, you blow bubbles.

Rocket Guy had a string of bubbles coming from his mouth... until about halfway across the pool, when they stopped. He was obviously breathing through his regulator!

He seemed a bit surprised when the instructor finally signalled "Go Up" and explained it to him on the surface.

Ah well. As I hauled my dripping self out of the pool, I was grinning like a idiot. Truly, I love diving. Maybe I was a fish in a past life.

+ BCD = Buoyancy Compensator (or Controlling) Device. For most sports divers, an inflatable jacket like a lifejacket, which has a valve attached to the air tank and inflates and deflates. Fish have swim bladders, divers have BCDs. It also holds the air tank on your back. Utterly essential to diving as it's used to control your buoyancy both at depth and on the surface, where having something that keeps you afloat without you having to kick to keep your head above water is essential. You sometimes see "backmounted" BCDs, or "wings", where the air cell (which inflates) is on the diver's back. These are more usually favoured by technical divers, who typically dive with two or more tanks of gas.

* If you're wondering why on earth you'd do this, it's sometimes necessary if you're unlucky enough to get entangled in something and need a bit more wriggle room to get yourself free. And yes, the regulator mouthpiece stays in your mouth throughout.

++ Free-flow: when the valve in the regulator sticks open, meaning that the air flow doesn't shut off. This is a "fail-safe" feature. If the regulator fails, better it fails in a way that means you can still get air from it, albeit you are losing air very fast and need to head for the surface at the safest possible rate. Breathing from a freeflowing regulator is often described, accurately, as being like trying to drink from a fire hose.

** CESA = Controlled Emergency Swimming Ascent. Technique of near last-resort if a diver runs completely out of air and there is no-one around them to give them their spare regulator for their air tank. (Avoiding this situation is why divers are supposed to dive in pairs and stick close together. Also why you're meant to check your air gauge, often.) You keep all your gear on and swim directly up to the surface exhaling all the way. The exhalation, usually done by going "AAAAAHHH" like you're at the dentist's, is to ensure that the pressurised air in your lungs can safely escape as it expands on the ascent, so no lung damage should be caused. You can do this from anywhere up to about 9m depth. Beyond that depth, you are in (even more) serious trouble if you run out of air.

CESA is in the same category as wearing a car seatbelt. You don't ever plan to need it, and you should always do everything you can (drive carefully / stick close to your buddy and check your air gauge) to avoid it. But if ever you do need it, then, like a seatbelt or a parachute, you'd better hope it works first time, because if it doesn't, odds are you won't be in a position to use it again.

Diving does not have to be dangerous. Driving a car is probably more dangerous, and I don't fear for my safety when I get in my car. But equally, it would be stupid to pretend it has no risks, which is why driving / diving instructors train their students to do emergency stops / CESAs (and other safety techniques), and, most importantly, THINK.

Diving Terminology, Part I

As one continues to dive / read diving books / hang about aimlessly on Scubaboard.com, one accumulates random diving terminology, which I shall attempt to eludicate here for the enlightenment of all.

Here's probably as good a place as any to throw in an important disclaimer: I'm not a trained diving instructor and I have a grand total of 13 dives under my weightbelt. If you seriously want to learn to dive, go learn from the nice people who have trained specifically to do that. Don't rely for your safety on anything I say here. If you would like to point out something I've got wrong, please do so, I welcome all polite and helpful correction. (Impolite correction can bugger off.)

So, a term for your enlightenment:

Nosebreather. Rather derogatory diving term for non-divers. So-called because divers breathe only through our mouths, since that's where the nice large mouthpiece connected to the air tank goes in. To answer a question I've been asked, yes, the mask covers your nose (as I am demonstrating to the left, here) partly to stop the water from getting up your nose, but more importantly, so you can breathe out through your nose to blow air through the mask and get rid of any water that might have leaked into it. (Yes, the mask does stay on if you do this - you hold the top of the mask and look up whilst blowing out. Like so.)

Diving opinion is divided on the merits of diving vs non-diving partners. Those favouring divers as partners wax lyrical about the joys of floating effortlessly through some of nature's most awe-inspiring sights with your loved one by your side, and having a partner who understands the need to have the smell of wet neoprene permeating the house for two days. Others point to the frustration that occurs when your beloved appears to have been inexplicably replaced with a wetsuit-clad moron who seemingly cannot understand the simplest hand signals and keeps wanting to stop to look at the pretty fish.

For their part, non-divers display a bewildering inability to grasp the importance of not drinking on a Saturday night so that one can rise at 6.30am on Sunday morning to get changed into a cold layer of thick neoprene whilst standing on a towel behind a stranger's Land Rover so you can go submerge beneath the grey North Sea. On the other hand, obliging nosebreather partners can be most useful in terms of acting as surface support, keeping an eye on the car / kids / dog, and making the all-important thermos of hot tea. Thus the debate rages on.

More diving stuff as and when I can.

In far more important news, today the Oldest Friend and her hubby had their first baby! A little girl, 6lbs 9oz, mum and baby doing well. Yay! Can't wait to see the little one.