DIVE LIGHTS
BARRY COLEMAN, MERIDIAN DIVE CENTRE, 039-973281
When asking this question I always find out what type of diving are you doing? Deep Ocean Wrecks, Recreational Night Dives, Cave Diving and/or basic recreational diving all have their preferences. I have used most of dive lights in there various forms and with the exception of long cave lights I have settled for a canister battery pack and light head with a umbilical cable. I find that the ability to fit the canister out the way, be it on the tank strap or between the BCD wing and the shoulder straps very convenient. The head can be clipped on to any part of the BCD without being in the way and easily removed when I want to use it, which is quite often. I have the “Goodman” handle that allows my hand to slip through the handle mounting the light head on the back of my hand. This is a very popular method used by cave divers. By using this method I still have two hands free and my torch. The light lasts about one and half hours and is 50wat. The batteries are recharged after about 3 hours, so I get a good days dive and recharge overnight.
If I am planning on a deep (penetration) wreck dive, I use the same torch and with another as back up. The canisters do not have to very big as one is only inside the wreck for about 45min so burn time is well within limits. I am not a proponent of mounting torches on a helmet for dives; interrogating my dive buddy underwater with lights in his eyes and restricting his ability to see me is not good planning. If I was contemplating a solo dive, a helmet might be an option.
For cave dives a min of two torches is a standard requirement. Again the canister with cable and torch head is my choice for both primary and back up. Plus I like to carry a small pocket type torch. The difference with cave diving is that the battery life (Both primary and backup) needs to be min 1.5 times longer then the expected dive time.
TO HAVE, OR NOT TO HAVE, A MANIFOLD ON A TWIN SET – That is the question!
BARRY COLEMAN, MERIDIAN DIVE CENTRE, 039-973281
Firstly lets do the FOR and Against TEST, then you decide which you are comfortable with!!
For (To Have a Manifold)
1. Allows the flow of AIR to both First stage Regulators. In the event of an out of AIR Diver taking the second regulator gas in both cylinders will reduce evenly.
Thus less stress on both divers to independently monitor each cylinder gas supply.
2. Allows the diver to monitor one SPG. Less stress then monitoring two.
3. Reduced stress by allowing the diver to keep the second stage regulator in his mouth through out the dive, (without have to keep swapping to the other second stage on the alternative cylinder to keep gas levels even. less task load)
4. If a First Stage regulator should malfunction/stop working, it allows the diver to switch to the alternative second stage without loosing gas in one cylinder. He/she will still have gas supply from BOTH cylinders.
5. As a result of maintaining the quantity of gas supply, GAS management is less of a problem to manage in water and to theorise when planning.
6. Isolation in the manifold allows the gas flow between cylinders to be stopped, in the event of a leak on the Pillar valve of a cylinder.
7. Reduced equipment to manage in water. No need for TWO SPG and in some equipment configuration, no need for 4 second stages.
8. No need to buddy breath if one cylinder is down and your buddy is out of AIR. (You’ll both out of air soon in that situation!)
Against (Manifold)
1. One or Two O-rings (at the most) extra in the manifold as compared to independent cylinders with a First stage, one second stage regulator, one power inflator and one SPG, on each cylinder. BUT - If the single cylinder equipment configuration, includes, TWO-second stage regulators on each First stage, then there are more O-rings and TWO extra L.P seats, compared to a manifold twin set.
2. No need to switch off the isolation in the event of a leak on the pillar valve.
3. Greater concentration on the Gas supply at hand.
4. When checking tank pressure on the surface or underwater, one will not get caught with NO or little pressure in one cylinder. Isolation valve switched off when checking one cylinder thinking it is open and you are reading the pressure of both cylinders. Diver Error
5. Less likely to get the wrong gas mixture in cylinders as one would check both cylinders mixtures. Diver Error
My decision is to dive with twin set manifold option, and have being doing so for years with no problems. When talking to the likes of Paul Heinth, and Bill Stone, and reading the books of “Mixed Gas Diving” and others, written by the likes of Tom Mount, Bret Gilliam, Richard Pyle, and the founder of many safety rules in the caving world, the late, Sheck Exley,(All with years of experience) all agreed, that manifolds have more benefits then not having them.
CAVE AND TRIMIX DIVING
BARRY COLEMAN, MERIDIAN DIVE CENTRE, 039-973281
In every organisation there are minimum requirements to do a course. That doesn’t mean that the person is ready for the course. What do you think when can people do a Cave or Trimix course and go deeper than 60m. When is a person ready?
The question “When a diver is ready to do a technical dive course?” Has plagued the training agencies from the start. In an effort to address this problem they have set minimum standards to meet, before the diver can consider doing the technical training program. This is one way - the other way is to insure that the instructor meets a minimum level in order to train the diver.
Is this enough? Well statistics say Yes, other wise the agency’s insurers would be screaming! They look at the bottom line figures, which speak for themselves.
In the day to day training the more experienced instructor in the technical programs will allow those people who meet the minimum standards for the course to start that program, but may insist that they complete additional training to certify. The other advantage with most technical training agencies is that they have evaluation assessments after each session, allowing the student self-criticism and evaluation, based on certain standards for each course.
I have found these evaluations an integral part of the program, which clearly defines the standards needed by the diver. Students who are honest with themselves will know if they are up to the level needed to certify. The ocean takes no prisoners and suffers no fools
SO WHY DO I PERSONALLY LIKE TECHNICAL DIVING?
BARRY COLEMAN, MERIDIAN DIVE CENTRE, 039-973281
I would imagine people who are non-divers ask the recreational divers the same question.
How does one explain to them all the aspects that encompasses diving – that complete break from day to day hustle and bustle. The adventure that is still available to those who want to explore and find new life that we didn’t even consider right on our doorstep.
For me, technical diving is nothing more than an avenue to explore inner-space further. We have explored our shores extensively down to 40 and 50m and the scientists have a good understanding what is down there. After that, the exploration in deeper waters to 500m and more have also been explored extensively – but the range between 50m and 200m is still a grey zone. Diving at these depths can still show us new insights and information.
Now we are not scientists, but we can keep our eyes open and with cameras, it all helps in discovery.
I have a particular interest in deep wrecks as many of the shallower wrecks have been found or have broken up along our coast due to our heavy seas. The deep wrecks can be so exciting to dive on, especially when you are the very first person to set eyes on them since they sunk. Further, the marine life on them is also of tremendous interest. We have ships from the second world war, yet to be identified. There are sights that fishermen believe are wrecks and we dive on these - sometimes we find its only a reef and rocks and other time we hit a jackpot.
I have a strong understanding that nothing is taken from them unless it is needed to ID the vessel and/or for scientific reasons. This allows the new divers to see what a virgin wreck is all about!
Oh, I forgot to mention that I also love the planning, logistics, team building, implementation of the plan and the out come of a successful technical dive. The other side is that we have great stories to tell afterwards
TECHNICAL DIVING – DIVESTYLE ARTICLE Nov/Dec2005 Publication
BARRY COLEMAN, MERIDIAN DIVE CENTRE, 039-973281
What is Technical Diving? Well, lets first define recreational scuba diving, then we can look at “Tec “ Diving.
It is widely accepted that recreational diving is no-stop diving, with air or enriched air, to a maximum depth of 40 meters, within the no decompression limits of the recreational dive tables. During penetration dives, (wrecks/caverns) within the natural light zone. With some training agencies, the penetrating wreck dive is no more than a total linear distance of 40 meters from the surface. These limits will vary with each training agency.
Technical diving or better known as “Tec” diving is diving other than conventional commercial or research diving that takes divers beyond recreational diving limits. This will include, but not limited to, the following: diving beyond 40 meters, required stage decompression, diving an overhead environment, which is beyond the light zone, use of variable gas mixtures during the dive to reduce the equivalent nitrogen depth and/or to accelerate decompression obligations. Tec diving is equipment intensive and uses extensive methodologies, training and technologies to manage the added risk. The deeper the dive the risk is like an exponential scale, involving more hazards.
Over the years various instructional philosophies have been employed to meet the challenging nature of Technical diving. Unfortunately this is not an exact science and we are all on the evolution ladder.
Accident free diving doesn’t just happen. Tek divers must take Calculated risks, a good training program can help by developing the skill level, discipline and survival attitude that can reduce the probability of accidents. But it doesn't stop there, one must maintain a comprehensive effort that includes, amongst other things, an attitude of awareness, training, on going practice and planning.
Technical diving is not for everyone – it is a very discipline sport and divers need the correct attitude. It is not a sport that you learn over night and dive the next day. Even through recreational diving is very closely related, it can be worlds apart.
Diving beyond 40m on recreational equipment is NOT Tec diving, its stupidity!
Technical Diving has progressed a long way since the 60’s when the use of a harness with a single cylinder outlet, (or individual cylinders twinned with individual outlets with no manifolds) and the standard recreational regulator configuration were accepted as the norm.
Like anything, technologies improve too, for open circuit. The standard is twin cylinders with isolation manifold on a harness with duel bladders, and Tec 1st and 2nd stage regulator configuration, right up until today where we use closed circuit rebreathers with anything up to 12 hours underwater dive time, at any depth. The US Military are using closed circuit rebreathers at 500 m when deployed from submarines.
Those who are contemplating “Tek diving” need to investigate the training, which is available, as this type of diving needs to be taught by those with the experience behind them and the instructors must keep themselves up to date with the evolution of Tek diving. This sport is evolving quite rapidly and methodologies and techniques are constantly improving and being analysed
Tec Diving courses: you’ll find one of the most intensive and extensive courses you’ve taken; anything less than your full and serious commitment will not be enough, that’s after you’ve met all the pre-requisites. Hours of practicing and mastering new skills, then to apply what you have learned strictly, without compromise. If you invest the effort and money required, you will find it one of the most rewarding experiences you will have in diving.
In other issues we will cover:
Courses available and pre requisites
Equipment requirements
Equipment configuration
Dive planning
Dive technique
Respiration, circulation and breath control
Oxygen, Carbon Dioxide and other gases, their effects on the diver
Theories for Decompression Safety
Psychological and physical fitness for the technical diver.
You may have noticed that this is a very large subject and to help me, it would be nice for you to tell us which subjects you would like to read about first, plus email you questions to me and the best question and answer will be published in the next Divestyle issue.
So why do Technical Diving? I would imagine people who are non-divers, ask recreational divers the same question!…and your answer is …? Why do I like it? For all the things that diving offers plus more: the challenge, the discipline, the adventure, to find wrecks that have been long forgotten, never visited and/or challenging, hey – to go where no man has gone before, to seek out new life! I have heard that somewhere else before?
In every organisation there are minimum requirements to do a course. That doesn’t mean that the person is ready for the course. What do you think when can people do a Cave or Trimix course and go deeper than 60m. When is a person ready?
The question “When a diver is ready to do a technical dive course?” Has plagued the training agencies from the start. In an effort to address this problem they have set minimum standards to meet, before the diver can consider doing the technical training program. This is one way - the other way is to insure that the instructor meets a minimum level in order to train the diver.
Is this enough? Well statistics say Yes, other wise the agency’s insurers would be screaming! They look at the bottom line figures, which speak for themselves.
In the day to day training the more experienced instructor in the technical programs will allow those people who meet the minimum standards for the course to start that program, but may insist that they complete additional training to certify. The other advantage with most technical training agencies is that they have evaluation assessments after each session, allowing the student self-criticism and evaluation, based on certain standards for each course.
I have found these evaluations an integral part of the program, which clearly defines the standards needed by the diver. Students who are honest with themselves will know if they are up to the level needed to certify. The ocean takes no prisoners and suffers no fools.
Where are MY favourite sites for tech diving and sport diving and why?
My favourite dive sites for diving? Now that is hard! Can I say the Ocean!?
I have dived various sites in 30 odd countries around the world and many of these sites have no name. So for this question I will stick to South Africa.
For Sport Diving: I’ll have to say Aliwal Shoal as first and Sodwana Bay a close second. Aliwal Shoal has such a diverse eco system and Sodwana has a range of hard corals, in addition to everything else, which I’d say the two together would be top dive sites in the world. The two sites are within easy reach, where as anywhere else in the world one would have to travel miles to get to such a diversity. We are genuinely lucky to have this on our doorstep.
For Sport Diving outside South Africa: Barrier Reef, Red Sea, (Egypt and Sudan), Indian Ocean Atolls (various) and Lofoten Island (Norway /Artic).
For Technical Diving: I can say the Oceanos Wreck (Transki) is my favourite. For sites close to our base in Scottburgh, we enjoy Inside Edge at Protea Banks and various sites off Rocky Bay. They range from 50m down to 70m and provide us with virgin sites of untold beauty. Sodwana Bay has some very nice 70m sites and these we try to do at least 3 times a year.
Weather in General along the South Coast affection Aliwal Shoal.
The mighty Aghulas Current said to be the largest body of water movement heading south down the East coast of South Africa. Intensity of this current varies and has a direct impact on Aliwal Shoal.
This impact is in the form of warm and cold water currents, eddies, flows and upwelling. Without this water movement the Shoal would be a very different place. The current movement can be compared to smoke as it moves down the coast. This current is very difficult to predict as there are many other influences which contribute to the cycle, but one main influence are the weather systems (low pressure) that move up the coast in the opposite direction, against the current.
The size and position of the Indian Ocean high pressure will determine how far the low pressure moves up along the East Coast. “What has this to do with the Aliwal Shoal?” you might ask.
It has a huge impact on the Shoal with regard to the water movements over the Shoal, as the Shoal lies inshore of the Aghulas main current. Strong pressure systems, both high and low, have a direct impact on the Aghulas current, which has an indirect effect on the Shoal. The differences can go from warm blue water (26’C) from the north to cold upwelling from deep down the continental shelf (14’C). So on average the water temperature in winter is around the 20’C and summer 24’C. These may vary by about 2 or 3 degrees.
Trying to read these effects have always interested me. The rule of thumb generally is that the Shoal has better visibility during the winter months than the summer. The summer months have a larger Indian Ocean high-pressure system, which is full of warm moist air, causing far more rain along our coast than in winter. Unlike winter, when only the cold front (south wester’s) bringing rain, summer has high-pressure precipitation as well.
Rivers are pouring into the sea, thus effecting visibility generally. There are exceptions to the rule and in summer when the north to south current is over the Aliwal Shoal with warm blue water, heaven is right there! It is strange, but one time I remember (in summer) when this current suddenly moved further out to sea, causing a strong up welling and the water temperature went from 26’C to 15’C the next day, and then back to 24’C the following day. All I could put it down to was that there was a cyclone (low pressure) moving down the Mozambique Channel and the high pressure was blocking it.
Over the winter months diving after a cold front (low pressure system) has passed, the water generally cleans up and the viz improves. I would go as far to say that over all, during winter Aliwal Shoal can have better viz than Sodwana.
The currents over the Shoal have a close relationship with the pressure systems. In general, a strong North South current can be followed by a low pressure moving up along the coast. This can occur 24 –48 hours before. Unlike the wind, which changes from a North Easterly to a South Westerly quickly and slowly around to Southerly, Easterly and then back to North Easterly, the current does not.
Excluding the rise and fall of the tide the current over the Shoal, it is either North South or South North. People sometimes get confused with the change in tide effect, but on a whole it is either one or the other direction. Although as I said there are exceptions and that is the fun part of trying to predict!
Why Trimix? By Barry Coleman
Inert gas (nitrogen) narcosis has been a plague of deep divers since the invention of SCUBA. It is a problem that affects divers the deeper they diver, causing differing responses to nitrogen under pressure. The responses are associated with that of drinking alcohol, some individuals are more susceptible to affects then others. Like alcohol everyone is affected, even though they swear blind that they are fine!
Behnke,Thompson, and Motley concluded in 1935 that at pressures higher than three ATA (20msw) narcosis is apparent. Tests showed that it is characterized by euphoria, retarding of the higher mental processes, and impaired neuromuscular coordination. However, other test showed that diver training and mental conditioning have a great effect on a diver’s susceptibility to narcosis, BUT the human risk (survival) factor from 60msw down, is exponential.
The causes of narcosis is described by the Meyer-Overton hypothesis: any inert gas will exert a depressant action on the C.N.S. (central nervous system) when a sufficient quantity (dose) becomes dissolved in its Lipid phase. These act as blockers to the nerve conduction thus decreasing nerve transmission. Other effects are A) the reduced, consciousness of a diver, by depressing the reticular formation of the brain and apical dendrites of the cortex. B) Inhibition of enzymes which in turn reduces carbohydrate metabolism.
So to get around all that “stuff” we use “ TRIMIX”, (Helium, Oxygen and Nitrogen) the use of Helium capitalizes on the non-narcotic proprieties of the gass. However, even this gas has limiting factors. High-pressure nervous syndrome (HPNS) and this is a major draw back, (Below about 150msw). Helium produces a rise in the surface tension in the membranes. It is known that NITROGEN causes a fall in the surface tension. So we add Nitrogen to the Heliox (Helium and Oxygen) gass mix to get TRIMIX, thus reducing the risk of HPNS.
For most of the recreational diving market, depths of below 150msw are not on the schedule, although at the moment depths of 120msw are!
So divers can now “dial a High” mix and chose their narcotic depth after they have planed the best Oxygen mix for the bottom. The balance of the gas in the mix will be nitrogen. Trimix is becoming more popular for Videographer, photographers, rebreathers and any diver who requires precision abilities at depth.
There are disadvantages to TRIMIX and they are
- More expensive the Air
- More critical ascent rate
- Must use custom dive tables (although Trimix Dive computers are readily available)
- Increase equipment dependency
- Additional equipment needs
- Longer decompression obligation (Dependent on mix, Depth and dive time under 2 hours)
The Advantages are
- Reduced Narcosis levels & amnesia (Been there and remembered it)
- Less expensive then Heliox
- Increased safety on Deep divers
- Less breathing resistance then air
- Reduced CNS levels on dives over 2hours duration
- Reduced risk of HPNS
In the recreational diver market Helium is now used for dives between 30msw and 40msw (recreational trimix) using standard SCUBA equipment. This helps those divers who do not like the effects of Nitrogen at these depths and those divers using CCR (closed circuit rebreathers). The CCR diver is even recommended to use “Trimix” or Normoxic (21% Oxygen and Helium) gas, as it is referred to. The cost to the CCR diver is negligible and the benefits considerable. For the open circuit diver, dives below 40msw should be considered and, below 50msw should be required as standard practice.
