Every time you touch the coral, hit it with a piece of dangling dive gear, or brush against it with a fin, you kill it. That’s why scuba buoyancy control techniques are so vital to the survival of the reef.
One of the first skills a scuba diver should master is buoyancy control. It’s the art of command over the underwater realm’s anti-gravity like atmosphere.
When you get the hang of this technique you help conserve the coral for the pleasure of divers who descend after you.
Here are 7 elements of diving that make, or break, your skill at maintaining neutral buoyancy when you descend for your underwater excursions:
Be aware of your position during the dive.
Know your scuba equipment.
Keep a low dive profile.
Know your proper weight requirements.
Mind your fin style.
Practice your scuba breathing technique.
Don’t get in a big rush.
There’s no particular order for learning, and perfecting, these elements. Every one contributes to your scuba buoyancy control technique. Some of these elements interact with each other to work synergistically on your personal buoyancy control results. Each element also provides its own individual contribution.
When you’re aware of your position in the water you know how far the coral is from your deadly touch. You constantly adjust to maintain a distance that keeps you from dealing that deathblow.
Know your scuba equipment, what it’s doing, and how to use it to optimize for buoyancy control. This element interacts with weight selection, buoyancy control device (BCD) adjustment, scuba breathing technique, fin style, and dive profile to create the synergistic whole.
Part of buoyancy control is adjusting the amount of air in your BCD bladder to find the antigravity condition. Too much air makes you ascend, and you must keep finning downward to stay at depth. Too little air makes you descend, and you have trouble staying off the bottom – and off the coral.
The weight you carry dictates how much air you must feed into your BCD bladder.
Your scuba breathing technique adds air, or takes it away, from your overall scuba gear buoyancy.
Dive profile is the silhouette of your body, including your dive gear. Profile is the area of water you displace. The more air in your BCD, the larger the BCD, and the bigger your profile. Equipment hanging loose also increases your profile. When you have a large dive profile you have trouble knowing if some part of your profile touches, or comes close to touching, the coral.
A diver needs added weight to descend into the water. The human body is naturally buoyant – it wants to float. But add too much weight, and the body wants to sink all the way to the bottom. As a diver you must acquire the skill of choosing the right amount of weight to take you to depth, and let you float at depth when you get there.
Whole you’re diving you don’t see what your fins do, or where they go. A long kick pattern threatens to brush against coral without the diver knowing. One way to counter this is practice a shortened fin pattern, and make it a habit. Another way is to use the frog style of finning.
Your scuba breathing technique has a big effect on your buoyancy control technique. When you have the proper weight, and the right amount of air in your bladder, you stay motionless (vertically) in the water – except for when you breathe. As you inhale your body moves to a positive buoyancy condition, and you ascend with the added air. As you exhale your body goes negative, and you descend with the decreasing air in your dive profile.
Take your time as you dive. When you get into a hurry you often lose track of your position. Many divers bump into the coral unintentionally because they’re finning around too fast. Sometimes you can’t turn aside quickly enough to stay off the reef.
As an added benefit to diving slowly you see a whole bunch more than when you’re speeding around like you’ll never have another opportunity to see the sights.
Learn, and practice, these 7 scuba buoyancy control elements. Master the art of buoyancy control. And help maintain healthy color for future scuba divers to enjoy.
SUUNTO gas-integrated D4i, D6i & D9tx
Appeared in DIVER September 2011
THERE’S BEEN A LOT OF FUSS RECENTLY about a new type of lightweight hp hose, with lots of discussion on the Internet as to whether it is safe or not. I haven’t really got involved either way, because I haven’t used anything as crude as a hose connected between my tank and a mechanical pressure gauge in years.
Why would I? It’s as daft as having your phone connected to the exchange by a copper wire!
It was Guglielmo Marconi who said that radio transmissions were here to stay, and I guess he has been proved right over the years. Ever since Dr Crippen rued the day it was invented, people have been taking advantage of wireless links.
This is why I’ve been using wirelessly connected gas-integration of at least one of the diving computers on my wrist, and I’ve never had to worry about looking at a pressure gauge since. These gas-integrated computers not only tell you your decompression status and current tank pressure, but also calculate how long that gas is likely to last at the depth you are at, and at the rate you have been breathing it.
Of course, you can program in a reserve pressure too. If you keep your remaining gas time longer than your total time to the surface, you shouldn’t get into trouble.
I’m on record as saying that this feature has been one of the most important and successful advances in keeping divers out of harm’s way.
So let’s lay to rest some of the myths about these magical bits of kit. Firstly, your camera’s flash will not cause the computer to lose the transmitter’s signal. This might have happened once, to one of the first radio-linked computers, when used with a flashgun that employed an electronic vibrator to indicate recycling of the capacitors, but underwater flashguns haven’t used those in yonks. Usually they were eaten by the sharks that were attracted to them.
Secondly, you get an actual tank-pressure display as well as the gas-time prognosis, so you are always aware of the basic information.
Thirdly, there are fewer O-rings to offer failure points in a radio transmitter than in a hose and pressure gauge.
Fourthly, radio has been proved reliable. Even aircraft captains use it!
I’ve been in the habit of diving with two gas-integrated computers with two different transmitters. I admit that in the past I have backed up a single transmitter with a high-pressure hose and gauge.
Now I don’t need to, and having one fewer hose to deal with is a godsend. This is especially true when I twin up independent cylinders.
So what are the drawbacks? Well, you have to get the battery in the transmitter changed every few years. You could do this yourself, but diving computer manufacturers have proved that not all divers are sufficiently dextrous to do this successfully.
The transmitter, screwed into the regulator first stage, looks like a convenient handle for a helpful boat crew-member when hauling a tank on board. I’ve found that yelling: “Don’t hold it by that!” the first time it happens helps develop muscle memory for these people.
The other admitted problem with the Suunto computers of the past was the need to pair the computer successfully with the transmitter every time you are about to dive. An unsuccessful pairing results in a display that, instead of giving your tank pressure, declares: “Fail.” That’s a bit boring when you’re already on your dive.
The new range of Suunto computer-watches pair permanently the first time, and unless you choose to change a transmitter code because, for example, another diver on your boat is using the same one, they stay paired.
The “Fail” feature has been discontinued. Not only that, but all the computer-watches in the new range can be paired to give a wirelessly integrated tank-pressure display. The “i” suffix indicates this with the new D4i and the new D6i, and they are no bulkier than they were before.
I say this because the first gas-integrated Suunto computer-watch, the D9, was a little on the chunky side. For this reason, I chose to wear a D6 as a day-to-day watch instead.
Let’s address another myth about computer-watches, the one about the display being too small to read, or that you don’t get a full spectrum of information.
The dot-matrix display of the LCDs give figures as big as any full-size Suunto computer. You need to push a button to get peripheral information, but all the crucial stuff is there, loud and proud.
Setting up one of these computer-watches is even more intuitive, thanks to some changes in the software, now called “DM4 with Movescount”. The displayed abbreviations are more obvious now, including those for that all-important transmitter pairing.
Deep Stop/Surface Interval
The manufacturer tells me that the latest pressure sensor employed offers a much more accurate depth measurement than before, but how would I notice that? Deep stops can be selected, although a diver can choose to ignore them when the time comes, so I guess these are just an add-on and not crucial to the algorithm, rather like the three-minute safety stop at 5-3m.
Now you get both displayed, rather than one or the other. You used to have to pre-select one or two minutes as a deep stop, but now the algorithm calculates what is appropriate, and credits you in the shallows.
Countdowns are now in minutes and seconds. which is a bit more comforting than displaying a one-minute stop when perhaps only 25 seconds is required.
The actual surface interval is also now displayed between dives, and time-to-fly has been relegated to an icon. The memory logbook shows the average depth as well as the maximum depth achieved on a dive, and there’s bar-graph representation of the dive.
Suunto D4i & D6i
These computers, designed for use with air or nitrox, are rated for a maximum depth of 100m and 150m respectively. The D6i looks slightly more robust in its stainless-steel case, and it can be programmed for two different nitrox mixes, as well as being usable in freedive mode. Sampling rates are increased to a choice of seven, from every second to every minute.
I’ve rarely used more than two nitrox mixes when open-circuit diving, but I often do use two.
I’m often castigated by Internet warriors for diving with two independent tanks with differing nitrox mixes (using the richer mix for the shallower part of the dive) but I do this only for dives where others might make do with a single tank.
Dives on the wreck of the Rosalie Moller in the Red Sea or the Bianca C in Grenada are good examples. The D6i is perfect for this.
I’m pleased to note that the electronic compass display is switched on when you want it and stays on until you decide you need it no longer – unlike the annoying compass of the old D6. Now it is three-dimensional tilt-compensated too.
The new Suunto D9tx is just as bulky as its predecessor, but now uses the same Suunto/ Wienke algorithm as the Helo2. This means that you can add a helium percentage, and use it for open-circuit trimix diving.
It may have the same dimensions as the D9, but the titanium case has a serious gunmetal finish and less bling. It’s rated to 200m deep.
You can preset up to eight different gas mixes with oxygen percentages of 21-99% and helium percentages of 0-92%. It comes with a USB interface cable for downloading dives to a PC.
Like the D6i, it features a stopwatch mode that can be activated during the dive. If I have a complaint about the D9tx, it’s the strap. This might sound trivial, but it is not made of the same material as its siblings and, although it comes with an extension strap just like the others, it’s made of a different elastopolymer.
I found it difficult to thread through the buckle loop over a bulky drysuit-clad wrist.
See, Suunto? You’re not perfect!
The new-sounding alarms attempt to be reminiscent of what they are trying to tell you. For example, if the computer thinks you should be going up, it has a series of beeps with a rising note, and vice versa. There is also a different beep for gas-switch alerts.
I was reminded of something iconic diver Stan Waterman replied to a young diver on a liveaboard when he informed him that he had heard his computer beeping on a dive: “Oh my goodness. Does my computer beep?”
The fact is that when wearing a hood you need very good hearing to notice these audible alarms. I left one at my bedside in my hotel because I failed to hear the alarm-clock feature. I turned the audible alarms off.
There is a very useful features comparison function for the D9, D9tx, D6, D6i, D4 and D4i on the Suunto website.
Mares Icon HD Air
Appeared in DIVER September 2011
DIVING EQUIPMENT may be predominantly black nowadays, but blue is the color of the ocean and a fill of more than 150bar. Green is the color of the hillside and a fill of more than 100 bar. Yellow is the color of cornfields in sunshine and for caution, and maybe only a bit more than 50 bar. Red says less than 50 bar left, so get out of there! What am I talking about? Part of the display of the Mares Icon HD Gas computer. Of course, it’s all either displayed in figures with total remaining gas-time prognosis, or you can opt for a graphic of a scuba tank that changes color too. That’s the beauty, and I mean real beauty, of it.
Since the Icon HD came out, smart and Android phones have entered the market, and the computer is now offered with wireless gas integration.
It’s taken a while, and I guess Mares spent that trying to get round the Scubapro patent. I know that Suunto tried to do the same, and I don’t know whether it was successful or not. I do know that the Mares transmitter unit that plugs into the high-pressure port of a regulator first stage is quite a brute compared to the Scubapro/Suunto versions. The color display takes quite a lot of battery power so, before I could even get it to turn on, I had to charge its lithium-ion battery.
This can be done from a normal power socket, or from the USB socket of a computer.
It takes a little longer to pair up with its transmitter than some other computers, so you need to be patient. Once paired, it stays paired. I never had any doubts about its ability to render a tank-pressure display on the dive. The Icon HD can be used as an air or nitrox computer, or in gauge mode. It can be set for three different nitrox mixes per dive, and setting is as easy as using an Android phone.
The display, set behind clear mineral glass, is about the same size.
In the Water
Other than near the surface, when bright sunshine might compete with it, the display of this computer is as readable as any other available. It has the benefit of colour as well as contrast. At night, it’s simply phenomenal. The deco requirements seemed identical to those of the Suunto computer I used alongside it. This is not surprising, because they both use examples of Bruce Wienke’s RGBM algorithm, adjusted for leisure diving. The significance of any information displayed has its priority denoted by the colour in which it appears, hence the colour groupings of the different tank pressures. Like any Android phone, iPad or digital notebook, this item of equipment also has features available far beyond the core requirements.
All stops are predicted. A safety stop is indicated in green, deco stops in orange, deep stops in blue and maximum operating depth (MOD) in grey. Disaster warnings are red. When using two or three nitrox mixes, the graphic for the MOD is displayed in various shades of blue. Pressing one of the four buttons made secondary and alternative displays available too. You can look at a pretty graphic profile of your dive so far, with mandated stops if appropriate, and download your own maps of dive sites and even photographs with which to irritate your buddies on long deco-stops. In fact you could waste your dive playing with this computer rather than seeing what you originally came for. The only downside is that you need to charge it every night on a dive trip, because the charge appears to be sufficient for only around three long dives.
ALGORITHM Wienke-Mares RGBM
FAST ASCENT WARNING 12m/minute
NORMAL IN-WATER DISPLAY Depth, remaining no-stop time/ascent time, CNS loading, dive time, ascent rate, oxygen exposure, nitrox mix, water temperature
ALTERNATIVE DISPLAYS Dive profile plus profile including deco-stops; all stops including deep, deco and safety
DEPTH RATING 150m
DECO INFO Full
DIVE PLANNER Yes
LOGBOOK Yes, with graphic profile
PC INTERFACE Included
MODES Air, nitrox, multi-nitrox, gauge
Regulator Atomic Z2
Appeared in DIVER November 2011
The Atomic Z2 is a balanced piston-type design, with all the high flow-rate performance this implies. It has a high-pressure piston-seal system, in common with all Atomic regulators.
I’VE MADE NO SECRET in recent years that I like Atomic regulators. Why do I like them? Because they are made to a cost-no-object design by guys who quit a scuba manufacturing giant because its bean-counters wouldn’t let them do it.
That said, in these difficult economic times we divers are as hard up as everyone else.
While those merchant bankers who are divers can still afford to buy themselves an all-titanium Atomic TX2, everyone else is left smarting at the price. So the guys at Atomic have looked at ways of making their products more affordable.
Using a cheaper material than titanium is an obvious answer. The Atomic Z2 has most of the same features as its expensive sibling, but is made, like most regulators, from chrome-plated brass, though with some titanium and stainless-steel components. It is zirconium-coated for a tough finish. It is also slightly simpler, in that it has a fixed rather than a revolving turret for its low-pressure ports. A turret version is however an extra-cost option.
The Atomic Z2 is a balanced piston-type design, with all the high flow-rate performance this implies. It has a high-pressure piston-seal system, in common with all Atomic regulators. This affords low maintenance thanks to the corrosion-resistant materials employed, and a long servicing interval.
What don’t I like? Being a piston-type design, the Z2 relies on being filled with an anti-freeze liquid retained by a rubber band. I’m not confident that this is the best solution for use in the sort of cold fresh water we encounter at inland dive sites in winter.
All Atomic regulators are supplied nitrox-ready for mixtures up to 40% oxygen. It’s down to the owner to make sure the reg doesn’t get contaminated with dirt, oils or greases. The Z2 has two high-pressure ports, one each side of the main barrel.
The six low-pressure ports are arranged around what, at first glance, looks like a turret but is not. This could lead to problems with hose routes – except that a seventh lp port is located at the very end. This means that the first stage is set up horizontally rather than vertically on the tank valve for best results, but you still need to give all your hose positions careful consideration. The optional turret version has only five lp ports.
The Atomic Z2 second stage lacks that wonderful universal joint that joins the T2X to its intermediate-pressure hose. It’s a feature that makes the regulator comfortable in the mouth because the hose never pulls, yet it doesn’t affect the breathing performance.
The Z2 has far more in common with all other regulators in this respect. However, it is pressure-balanced, and it has the Atomic high-pressure piston-seal system that keeps the valve seat and the “adjustable dynamic orifice” apart when the valve is not pressurised.
This allows you to store the regulator for months without it mysteriously leaking gas the next time you want to use it. The separation avoids engraving of the valve seat during storage. I have had an Atomic regulator for many years without a service, and whenever I get it out of my cupboard it performs perfectly.
Low-friction-bearing surfaces keep this action working smoothly, and a Kevlar-reinforced polymer insert at the pivot-point of the titanium valve lever is partly responsible. The body of the valve is made from brass plated with zirconium.
Where other regulators feature a venturi control adjustment or a by-pass tube, Atomic second stages have a unique depth-sensitive automatic adjustment that the manufacturer likes to call the “automatic flow control”. A vane simply swivels in the flow of air within the second stage according to the pressure applied to it by the water.
It also has an adjustment for the cracking effort needed to open the valve initially. I have always left this set at maximum, and I’m pleased to see that the manufacturer explains that tightening up this control actually adds to the work of breathing rather than saving air, as I have heard some people misinform other divers.
In the Water
Anyone who has jumped in and dislodged the exhaust valve of a regulator will appreciate that this can make it so wet to breathe from that it is virtually useless.
Atomic employs an elliptical exhaust valve, which it claims dramatically reduces the work of breathing at depth. It is so substantial that there is no way it could be dislodged by a sudden inrush of water.
I missed the universal joint on the hose, but I still enjoyed the Atomic mouthpiece, which has to be one of the best ever made. I asked Atomic to send me a few spares some years ago, and have fitted them to other makes of regulator I have used. It’s proven that the apertures in the front of a second stage have a dramatic effect on the regulator’s ability to perform to the highest level.
It is also my experience that when stationary in a strong head-on flow of water, as one might encounter watching animals at Manta Sandy in Raja Ampat, at Blue Corner, Palau or at one of the Express sites in the Maldives, a regulator can be affected and free-flow annoyingly. Atomic has thought of this too. The holes in the front cover of the second stage are so designed that they direct any inward flow of water to the sides, and not directly on to the pressure-sensing diaphragm. It works. Not only that, but the Z2’s front cover is flexible, so any part of it can be pressed to operate the purge control. As with all Atomic regulators, it breathed sublimely. I couldn’t give it 10 stars because it’s not an Atomic T2X, but it is available to buy at an incredibly attainable price.
Regulator MARES ABYSS NAVY
Appeared in DIVER July 2011
The Mares Abyss Navy looks and feels exactly like some other current Mares Abyss regulators, except that this one has an all-black second stage – although I guess that members of special forces on covert operations would blank out the glittery Mares badge.
THE ANCIENT PHARAOH HAD A DREAM, and the Israelite Joseph interpreted it for him. His dream involved seven fat cows that were devoured by seven thin cows.
Joseph said that seven years of plenty would be followed by seven years of drought, and that the Egyptians should plan for that.
Well, that’s ancient history, but it does seem that many modern businesses experience cycles of success.
Mares, the Italian manufacturer of scuba gear, had its fat years, but more recently times seem to have been a little leaner.
This was not because it didn’t continue to make excellent products. It was linked to hiccups in its supply chain and the more aggressive marketing of its competitors.
The Mares Abyss Navy looks and feels exactly like some other current Mares Abyss regulators, except that this one has an all-black second stage – although I guess that members of special forces on covert operations would blank out the glittery Mares badge.
I’m told that this reg has been approved for use by the US Navy, hence its name.
When he was young and in the US Navy, my old friend Bret Gilliam spent a lot of time hanging about at great depths waiting to photograph the odd nuclear submarine as it stormed past him. I get the idea that something like that appearing out of the gloom at a particularly fast rate of knots is enough to raise anyone’s breathing rate, and he would have been very grateful for such an efficient bit of kit.
We have to thank the likes of Ian Himmens and Stan Ellis, who developed their erformance-measuring ANSTI machine since then, for the fact that there are few if any poor performers among scuba regulators now.
This Mares Abyss Navy certainly looks serious.
This is a typical Mares balanced diaphragm-type design, with its two high-pressure ports angled steeply away, so that pressure gauges (or computer transmitters) are not fouled by any other hoses. The hoses are heavily marked for function. There are four medium-pressure ports, and these too are angled away from each other.
Characteristically, the port for the primary take-off to the second stage is of an over-sized gauge, allowing a wide-bore interstage hose to be used.
It’s quite a brute, with a great deal of metal surface area for good heat-exchange, and looks to be taller than other Mares first stages.The diaphragm is oil-sealed by means of an extra part which is screwed onto the top of the valve to reveal the heavy-duty external pressure-sensing diaphragm. I wouldn’t give it to a child to play with, because I found the lugs let in to engage a servicing tool were on the sharp side, and could easily cut a finger softened by long immersion in the sea. The intermediate-pressure hose is of traditional rubber design, for its superior heat-exchange properties and ruggedness.
Black is the new black. Mares has abandoned the Flash Gordon retro-look it gave some Abyss second stages recently. Apart from this, there are few surprises in the design of this part. It is very neat and compact, and has the familiar Abyss all-metal style, with only a small amount of plastic.
The front vent to the depth-sensing diaphragm is perforated with many small holes so that the effects of being head-on into a flow of water are mitigated, and free-flows avoided.
The purge button is clearly located in the centre of this, and presses on the valve lever for a progressive, effective flow when you need it.
There are no knobs for users to fiddle with in the water. None are needed, because it also has the familiar Mares-patented Bi-pass tube, which feeds gas directly from the second-stage valve to the mouthpiece, avoiding any fast flows across the inner side of the diaphragm.
These fast flows can lower the pressure at that point, causing the diaphragm to be pushed in further, and thereby opening the second-stage valve more and increasing the gas flow. The result is exponential, making inevitable the sort of free-flow associated with freeze-ups in cold fresh water. The Bi-pass tube avoids this.
The main difference between this and other Abyss regulators is that all the metal parts have a fluoropolymer resin finish in matt black, and the small amount of plastic used is all matt black too. Even the hose protector, again perforated with holes to allow water to pass to the in-line heat exchanger, is finished in a matching matt black.There is a single exhaust port, and the exhaust-T includes a protrusion that ensures that the exhaust port is kept in place. The exhaust-T is small but big enough to ensure that exhaled bubbles don’t become an annoyance.
As usual with Mares regulators, I felt that the mouthpiece was a little soft and flimsy when used in warm weather.However, it hardens up to be quite adequate in a cold inland site, and it is use in cold water for which this regulator is intended.
In The Water
It’s getting more and more difficult to differentiate between the performances of top-of-the-range regulators. Mares claims just less than 1 joule/litre for the total work of breathing, and this is twice the figure claimed for some other regulators.
This said, neither figure represents much effort at all, when you consider that not long ago manufacturers were trying to beat the 3 joule/litre barrier, and high gas-flows represent a likelihood of exponential free-flows in the cold.
So although in side-by-side comparisons the Abyss Navy might seem harder to breathe from, this doesn’t amount to a hill of beans, as I’m sure those guys in the US Navy might have said. It’s just nice to know that it isn’t going to turn into an uncontrollable gas geyser in cold conditions.
I couldn’t get into the second stage easily to look at the lever action on the pressure-sensing diaphragm on the opening of the valve. Mares discourages anyone but a service technician from taking it apart by marking the fixing screw with a blob of red paint.
Too often, regulators can be reassembled incorrectly by the unskilled, leading to ingress of water and a wet breathe.
This robust, all-black, all-metal regulator looks the business and meeting US Navy performance criteria is no mean feat. I don’t know if it’s a psychological effect of the black finish, but it looks a lot meatier than some other superficially similar Mares regulators.
The excellent hose routeing of the first stage, especially favourable for divers using more than one cylinder, combined with the oil-sealed effect of the coldwater kit and the tried-and-tested Bi-pass tube of the second stage, are bound to appeal to extreme divers. Metal makes for good heat-sink characteristics.
The all-black finish will make divers look well hard, too! Perhaps this will signal the start of a new era for Mares.
The regulator that beats every record, now even lighter
• Record-setting performance
• Lighter new version of the most famous Mares first stage
• Softer and lighter new hose
Abyss gained its reputation for reliability by setting many diving records, such as the deepsolo-dive to -313m and 101 divers breathing simultaneously for 40min from a single MR22 first stage. Our tradition for excellence keeps on evolving due to our new engineering and design.
First stage: Balanced diaphragm design
Lightweight yoke: No
First stage weight (g) INT: 803
First stage weight (g) DIN300: 616
First stage weight (g) NX: 656
Second stage weight (g): 269
Total weight (g) INT: 1230
Total weight (g) DIN300: 1040
Total weight (g) NX: 1083
Second stage dimension: Compact
Oil/Dry cold water kit: Oil
HP Ports: 2 HP 7/16” UNF ports
LP Ports: 1 LP 2” UNF ports (primary), 3 LP 3/8” UNF ports
Inhale pressure: 9.85
Inhale pos pressure: 3.45
Exhale pressure: 9.06
Ext work breathing: 0.92
Inhale work: 0.27
Pos inhale work: 0.02
Exhale work: 0.65
Pressure depth: diagram at 50m (165ft)
Pressure diagram: 216