No matter what level of diver you are there’s one thing that stands true for all: buddy checks. The truth of it all the higher level of certification usually the more things can go wrong. It’s important that before every single dive you and your buddy go through a buddy check of each other. We’re giving you some guidelines on what you should be doing before every dive.
Over the last 10 years SDI/TDI/ERDI has seen tremendous growth throughout the world. Due to our growth outside of the United States, we recently decided to expand the staff working with Paul, by adding Jordan Greene, an experienced member of our staff, and Mark Powell, a long time IT for SDI/TDI/ERDI from the UK.
The fact is, the diving industry and “marketing” have gone though a very similar evolution process.
by Mark Powell
One of the most important techniques in marketing is the concept of segmentation, targeting and positioning (STP). These three tools allow businesses to identify their most likely customers and tailor messages to these customers in order to increase their chances of offering the right product to the right customer.
Segmentation is the process of splitting up a huge group of all possible customers into meaningful sub groups. Segmentation is often done on demographic lines such as age, gender, income levels, family size, home address or work address. For example, a business may split its customers into male and female customers or into customers that are in their teens, 20-30, 30-40, 40-50 and over 50. Alternatively, a business may distinguish between customers that live within 10 miles of their store and those that live more than 10 miles from the store. In addition to these objective demographic categories, segmentation can also be carried out on a more subjective level, such as life stage, personality or behavioural characteristics. For example, life stages might include single, married with no kids, married with young children, etc. Although there is a correlation with age it is not fixed. For example a married couple in their forties may have no children, one young child or two teenage children. The key point of segmentation is to pick segmentation criteria that are relevant to the product or service you are offering.
Once you have chosen your segmentation criteria, the next step is to select various segmentation groups to target. For example in the video games market, age and gender are commonly used for segmentation. Early targeting strategies focused on males in their teens and early twenties. As a result games were developed that appealed to this target group. However, as the industry developed it was realized that there were other potential target groups. Older customers from both genders were targeted for a completely new genre of games involving brain training and female customers in their 30s and 40s were targeted for games such as the Sims and Farmville. By the use of suitable segmentation criteria, the games industry was able to hugely increase its potential market. It is only by the use of segmentation and targeting that this was possible. If they had tried to offer the same product to all groups they would have failed to expand beyond their initial market, however by realising that there were different segmentation groups the industry could offer a more suitable product to each of those groups.
This third stage is known as positioning. This involves offering a product that suits the target group and communicating with that target group in a suitable manner. In the video game example, positioning started with offering a radically different product to each target group. In other cases the same or very similar products can be positioned very differently by means of packaging and advertising. A good example of this is Diet Coke and Coke Zero. What is the difference between these two products? There are some minor differences in the recipe but ultimately they are almost identical in terms of the actual product. The real difference is that Diet Coke is aimed at women and Coke Zero is aimed at men. As a result, the product packaging for the two is very different and if you have ever seen a Diet Coke advert it is obvious that it is aimed at women while Coke Zero adverts are clearly aimed at younger men. In this way Coke can position their product specifically for the relevant target markets. Trying to come up with an advert that appealed to both men and women would be much less effective overall.
Positioning your scuba diving courses will also depend on your target group. One target group may prefer online training while another may prefer the face to face approach. One group may be attracted by action and adventure while another may be worried about the risks involved. One group may be interested in marine life and the environment while another may be more interested in exploring wrecks. One group may be interested in diving in far flung exotic places, while another maybe more interested in being able to train locally without the need to travel away from home. By coming up with an appropriate set of target groups you can put together a set of offerings that appeal to those target groups.
As well as product specification and product imagery, positioning can also affect your choice of advertising medium. National TV advertising on a major channel can have a huge reach but is a very expensive and an inefficient method of reaching a specific target group. If your target market lives within 10 miles of your dive centre then local advertising will be much more cost effective than national advertising. If you are targeting new divers, diving magazines or online forums are not the right place to look for those customers. However, if you are targeting experienced divers who are looking to get into technical diving then they are much more appropriate. If you are targeting inexperienced divers who want to gain more experience then your open water students over the last few years are the best starting point.
Segmentation, targeting and positioning is not a magic bullet but if used correctly it can help any business owner identify likely groups of potential customers and help you think about how best to position your offering to those customers.
Why do divers do stupid things? Well the short answer is because they are stupid. Now I know that the majority of the readers of this article are going to be divers and it’s not usually a good idea to start off by insulting your audience but bear with me.
By Mark Powell
The image that many technical divers try to promote is that they are tough, macho divers. The shaved heads and stubble, combined with equipment that would make a Special Forces diver look inadequate, all add to this image. The message is that they can leap tall buildings in a single bound and endure conditions that no mere mortal could withstand. However the truth is a little different. In fact many technical divers spend as much time thinking about how to stay warm during their dives as they do planning the dive itself. The reason for this is that technical dives are more challenging than many recreational dives. They are typically deeper, longer, and colder. The intelligent technical diver recognises this and tries to protect against the cold wherever possible.
One of the main concerns of any technical diver is warmth, both from a comfort and a safety point of view. In general the deeper we go the colder it gets. A few years ago I was teaching an Advanced Trimix course in Turkey and between the surface and 80m there was a difference in temperature of 10 degrees. This meant that while we might have been comfortable on the surface you would get very cold at depth. Gloves intended to keep my hands warm at depth were uncomfortably warm during the decompression. A more common problem is that technical dives tend to be much longer than recreational dives and will usually involve long decompression stops. Even if there is no difference in temperature during the ascent it is common to get colder during the decompression. I don’t normally get too cold during the main part of the dive due to choosing the right undersuit, swimming around and the fact that my mind is occupied, but during decompression it is much more common for me to feel the cold. During long decompression stops you are not swimming around or moving to any great extent and your mind is not as occupied. It is during these long periods of mental and physical inactivity that I often feel the cold.
In addition to the comfort aspect of getting cold there are a number of very real safety issues involved. The cold can slow down your reaction speed and thought processes which, when combined with Narcosis can affect how quickly and effectively you react to problems. Cold hands can also quickly lose dexterity which can make it difficult to effectively handle equipment, operate computers, switch to decompression gas, etc.
Most importantly there is strong evidence that getting cold towards the end of a dive can increase the risk of decompression illness. During the early parts of the dive the diver is fairly warm and blood flows to all parts of the body. Nitrogen and Helium are carried by the blood flow to the whole body and the level of the inert gases dissolved in the body increases. Towards the end of the dive, during the ascent and decompression stops, the inert gas is normally carried by the blood back from all parts of the body to the lungs. However when we get cold one of the body’s reactions is to restrict blood blow to the extremities and concentrate it in the main core of the body in an effort to conserve heat. When the skin temperature starts to drop the body will reduce the circulation in your limbs, this is known as vasoconstriction. This has the effect of reducing the amount of blood flowing to the heavily inert gas-laden tissues in the extremities which in turn reduces the level at which Nitrogen and Helium off-gas from these extremities. In effect, being cold has slowed down the release of inert gas from these tissues. As a result the speed of off-gassing is slower than predicted and the excess Nitrogen and Helium in these tissues can cause decompression illness. Recent research has shown that this can cause a significant increase in the risk of decompression illness.
Due to the risk of decompression illness, suit floods and leaks are much more important to a technical diver. I know many sport divers whose suits regularly leak and for them it is merely an inconvenience however for a technical diver it can be a much more serious problem. Similarly a flooded suit can be cold, uncomfortable, inconvenient and irritating on a recreational dive but on a long decompression dive it can also be very dangerous. As the diver gets cold their decompression become less efficient. This means that at the very time they want to get out of the water they need to stay longer to make up for the inefficient decompression. Here it is a balancing act between the dangers of hypothermia and decompression sickness.
It is a combination of the comfort and the safety that makes technical divers so concerned about the particular design of undersuit they use. There are a range of undersuits that use different materials to keep the diver warm. In addition to keeping the body warm it is vital to keep your hands warm. As we have seen cold hands can cause problems with dexterity making it much more difficult to carry out certain tasks. For this reason a technical diver will also think long and hard about their choice of gloves for long cold dives. One option is to simply wear thicker gloves. The extra thickness helps provide better insulation for the fingers although the thickness of the gloves also results in reduced dexterity. The same problems apply with 3 finger mitts. These mitts have one compartment for the thumb, one for the index finger and a third compartment which contains the remaining three fingers. Having the three fingers together helps to keep them warm although the thumb and index finger get just as cold as in standard gloves. In addition having the three fingers together significantly reduced dexterity for some tasks and can make some standard hand signals difficult if not impossible. Again there is a trade off between warmth and dexterity. By getting cold we can lose dexterity but many of the gloves designed to keep our hands warm have the side effect of reducing our dexterity anyway!
Another option is dry gloves. These are gloves that are fully sealed against the drysuit and allow no water into the glove. In some designs the glove is linked directly to the airspace of the drysuit. This removes any problems with equalising the two air spaces but has the risk that a punctured glove can cause a complete suit flood. Other designs have a standard seal on the dry suit so that the dry gloves are a separate air space. In this case some mechanism is required to allow equalisation of the air space in the gloves so that the diver doesn’t get uncomfortable squeeze on their hands on the way down or excessive expansion of air in the gloves on the ascent.
The typical image of a technical diver is some macho tough guy however, as we have seen, the reality is that technical divers are more concerned about keeping warm and comfortable than most other divers because the consequences of getting cold can be far more serious on a decompression dive than on a recreational no-stop dive.
by Mark Powell
By: Mark Powell
There are not many diveable aircraft carriers in the world so diving any aircraft carrier is a special experience but diving HMS Hermes, the first purpose built aircraft carrier, is a unique experience. There had previously been a number of merchant ships that had been converted for use as an aircraft carrier but HMS Hermes was the first to be commissioned specifically as an aircraft carrier. The Royal Navy, despite a very traditional approach in many areas, was at the leading edge by ordering the first purpose built aircraft carrier in July 1917. She was laid down in January 1918 and launched in September 1919 and so was too late to be of any use in the First World War. She was finally commissioned in July 1923 and so didn’t see active service until the Second World War where she was based for much of her time in Ceylon, now known as Sri Lanka.
In March 1942 the Japanese Navy was ordered to carry out an aggressive raid on Sri Lanka and any British shipping in the area. Vice Admiral Nagumo, who was also responsible for the attack on Pearl Harbor, had a large fleet of aircraft carriers, battleships, cruisers and destroyers. On 9th April the Japanese launched their attack with more than 80 Japanese Zero fighter bombers attacking HMS Hermes. Due to a lack of fighter cover Hermes had to defend herself but despite opening fire with every gun it was clear that she was almost helpless against such an onslaught. Numerous bombs struck the ship and she sunk in less than an hour with the loss of the Captain, 19 officers and 288 ratings on board.
Despite being an incredibly important historical wreck HMS Hermes has lain almost unknown until recently. This was because between 1983 and 2009 Sri Lanka was ravaged by a vicious civil war which had meant that the Hermes was inaccessible to divers due to the political situation. Since the end of the civil war it has finally come possible to dive her.
The aim of this project was to determine the state and layout of the wreck. A secondary objective was to search for some of the other wrecks that were sunk at the same time as HMS Hermes. These were two support vessels, HMAS Vampire and HMS Hollyhock as well as the RFA tankers SS British Sergeant and SS Athelstane.
Despite the end of the civil war it was still a major effort to get to the wreck. Sri Lanka is a ten hour flight which is followed by a seven hour bus journey to get from the capital Colombo to Trincomalee where the boat departs. First impressions of the island are that despite being obviously very poor it is very clean and colourful with lots of small businesses. There are lots of fruit stands, hardware shops, and mechanics for the scooters and motor bikes that seem to be everywhere. I am struck by how lush and green it is. There are cows wandering the street, Buddhist shrines along the roadside, in fact all the developing world stereotypes. Later we even see three elephants wandering the road.
Diving HMS Hermes for the first time was an unforgettable experience. As we drop down the line we can see that the visibility is excellent, it drops a little after 30m but is still impressive. The shot is right on the wreck, near the flight control tower and almost on top of one of the guns. After we tie in the shot it’s time to explore the wreck. She lies on her port side in 52m/170 feet and I head along the deck towards the stern. The shot is at the forward end of the flight control tower so I can see the main part of the hull on my left and the tower on my right. As I get to the end of the tower I come across the second of the main guns. From this point onwards I am swimming along the side of the hull where the flight deck should be exposed but in this area the wreck is almost inverted so it is difficult to see the scale of the flight deck. I pass another main gun before getting to the stern. The starboard prop is standing clear and makes a very impressive sight. The portside prop is partly buried in the sand and is only partly visible. I make my way slowly back along the wreck until I get back to the shot and have a look around this area before reaching my planned bottom time of 45mins. We all have similar plans and so the whole team ascends together with smiling faces all round.
Over the next few days we further explore the wreck and document its current state. Despite obvious damage and the collapse of the flight deck there are areas that are undamaged and look almost as they would have when the wreck sank. The control tower is almost intact and gauges, complete with glass, are still present as well as a range of other fittings. Emergency lights are still in place with the light bulbs still preserved.
At the bow the anchor chains as well as the anchor are clearly visible. The decking has come away from the bow and it’s possible to see right into the fo’c’sle of the ship. A row of toilets are clearly visible together with an intact lamp fitting in the ceiling. Beyond this it is possible to see down through several decks and light penetrating through the hull shows that there is a hole in the hull a couple of decks down. Looking in through these holes gives a clear indication of the layout of the forward part of the ship. I can’t help but think of the men who served, and in many cases died, on this wreck. The wreck serves as a museum to this unique piece of history as well as a monument to the men who perished on her. I hope that anyone who dives this wreck takes the opportunity to remember these men and treats the wreck with the respect it deserves.
The wreck is home to a large variety of marine life. Large tuna, grouper and jacks flock around the wreck as well as a huge number of other fish. Some of these are of impressive size with one grouper being considerably larger than me. Some of the tuna are also a very impressive sight. As well as the fish, a huge variety of coral and other marine life means that there is significantly more life on this wreck than on the vast majority of reefs.
During the expedition and subsequent dives I have kept the HMS Hermes Association informed of all our plans. I wanted to make sure that we only ever acted in accordance with the wishes of the survivors and the families of those who perished. As I type this there is now only one survivor. Leading Seaman Stan Curtis was fascinated to see the photographs and video we brought back and was very grateful that we had paid tribute to his comrades who did not survive the attack. I also received a very humbling letter from the daughter of one of the survivors. “ I was moved to tears because my lovely Dad P.O. Henry Walker was a wonderful swimmer and loved the sea, living as we did on the coast of the Irish Sea, I long remember times spent on the beach being taught to run into the icy cold waves and dip down quickly then shown how to swim and float. He would then leave my brother and I to swim out to the Whitehaven Harbours, only to be pointed out by my Mam of a small head appearing in the distance which was that of my dad. The point I’m making is that I always thought of how cruel the sea was to take him from us, but on reading of the world class wreck – the fish and beauty of the coral, and the statement of the writer to it having More Life On This Wreck than on the majority of reefs, fills my heart with JOY and found myself thinking. What a lovely and suitable resting Place for my Father… Just what he would have wished himself. Hopefully others having lost loved ones on the Hermes 9 will be consoled by this.”
I think that expeditions like this can help to keep the memory of events such as this alive. I have also come to realise that, when carried out sensitively, they can provide comfort for those left behind.
Contact SDI TDI and ERDI
If you would like more information, please contact our World Headquarters or your Regional Office.
Tel: 888.778.9073 | 207.729.4201
Email: Worldhq@tdisdi.com
Web: https://www.tdisdi.com
https://www.facebook.com/TechnicalDivingInt
By Mark Powell
Photo provided by Pete Nawrocky
A rebreather is a fantastic tool that can be used to extend the range of what is possible in terms of exploratory diving. For deeper and longer dives, rebreathers can significantly reduce concerns over gas usage. That is, unless there is a problem. If you are unable to use the rebreather for whatever reason and need to bail out then the rebreather becomes a very expensive BCD. Not only that, but you are right back to all the limitations of open circuit gas volumes as you need enough bailout gas to get you safely back to the surface.
For dives without any mandatory decompression stops, this is relatively straightforward. As there is no decompression obligation we simply need enough gas to be able to ascend to the surface. A stage cylinder can provide plenty of air for the ascent. However, as we progress into decompression diving, the amount of gas required becomes more of an issue. The advantages of a rebreather include the fact that you can do much longer dives due to avoiding the limits of open circuit gas volumes. Together with the optimized mix that the rebreather gives you, this means that many divers will do longer dives than an equivalent open circuit diver. However, in the case of a bailout, you need to carry enough open circuit bailout to ascend and decompress safely. This means that even though you may not be planning on using those stage cylinders, you still need to carry them, just in case.
When performing any gas calculating, including calculating the amount of bailout gas you need to carry, the divers breathing rate is a key element of the calculation. Whatever your average breathing during a dive, you can guarantee that if you bailout your actual breathing rate will be much higher. There is always a reason why you have bailed out, even if it is only an imagined reason; whatever the reason, it is bound to increase your stress levels and hence your breathing rate. One of the situations where you would definitely bailout, and not return to the loop, is where you have a carbon dioxide breakthrough. In this case you would definitely not return to the loop and would need to do the entire ascent on bailout, but more importantly, you would have an even higher breathing rate. For these reasons TDI recommends using a breathing rate of at least 45 l/min (1.0 cf/min) until the first deco stop when calculating bailout gas requirements. In reality, even this rate may be exceeded for the first few minutes of a carbon dioxide breakthrough.
For deeper dives the volume of bailout gas to be carried can quickly become very significant. For dives below 80m (260 ft) this can become problematic, and the additional cylinders can introduce problems with drag and can, in themselves, become an issue due to the effort required to swim with them. TDI believes that each diver should carry enough bailout gas to be able to get them to the surface. An alternative approach is team bailout where the divers between them carry enough bailout gas to get one team member to the surface. This is not a technique to be used without specific training and unless you are diving within a well-practiced team. For most rebreather dives this means that the limiting factor for the dive is not scrubber duration, exposure to CNS or anything else related to the rebreather itself but rather the amount of bailout that can be carried.
The gas selected for the bailout cylinders requires some thought. As they will hopefully not be required, rebreather divers tend to use a standard set of bailout cylinders and gasses that will be used for repeated dives. The first bailout bottle needs to be breathable at the maximum depth as the diver may well have to bailout on the bottom. It is common to use a first bailout that has a higher partial pressure of oxygen than the setpoint being used on the rebreather. This is to optimize the decompression ascent. Subsequent bailout gases are chosen by balancing out the decompression requirements and the gas planning requirements.
Another technique that is sometimes used, and is starting to appear in some planning tools, is to modify the decompression model so that a different approach is used for a bailout ascent rather than a normal ascent. When ascending normally the diver may well want to use deep stops or some form of bubble model approach. However, during a bailout the diver may want to get shallower slightly faster than they would otherwise have liked in order to reduce gas management problems.
Until rebreathers with built-in redundancy of all features or bailout rebreathers become common place, we will still need to plan for bailout. Until that point, rebreather divers will still ultimately be limited by the restrictions of open circuit gas calculations and the ability to carry sufficient bailout.
Contact SDI TDI and ERDI
If you would like more information, please contact our World Headquarters or your Regional Office.
Tel: 888.778.9073 | 207.729.4201
Email: Worldhq@tdisdi.com
Facebook: www.facebook.com/TechnicalDivingInt
by Mark Powell
Have you ever ended up separated from your buddy or dived with a buddy who’s not really paying much attention to you? Are you an instructor who takes students on their first dives?
At some point all divers have been, or will be, diving solo – whether they intend to or not.
This presentation by leading technical diving instructor Mark Powell challenges the common misconceptions around solo diving and provides useful, informative tips on how to stay safe and get the most out of your diving.
A must watch for all divers, recreational and technical alike.
Filmed at the London International Dive Show (LIDS) in April 2012.
If you would like more information, please contact:
Tel: 888.778.9073 | 207.729.4201
Email: Worldhq@tdisdi.com
Web: https://www.tdisdi.com
Facebook: www.facebook.com/SDITDI