Training

One of the things I am drawn to, and quite skilled at, is processing data. It’s why I enjoyed operating a fire truck, and it’s also why I like my job in medicine and enjoy the technical end of SCUBA. I would probably been pretty good at engineering. I love processing data and doing math in my head. I also enjoy having a good tool that will make that job easier.

Enter dive computers. These machines take all of the guesswork out of diving. Traditionally, divers would use a table where the maximum depth and total dive time were looked up on a table that would tell you the maximum time you could be underwater. This is called “square profile” diving. The table assumes you descend from the surface to a set depth, remain at that depth the entire dive, then return directly back to the surface. In reality, no one dives like that.

A dive computer uses a mathematical model to calculate how much Oxygen (and other gases) are in your tissues, then uses that to tell you what you need to do in order not to get the bends. It resamples the factors of the dive every 30 seconds.

That’s one of the things that I can’t understand about this diving accident. The diving computer would have warned them:

• that they were approaching the no decompression limit once they had been under for about 7 minutes at a maximum depth of 160 feet. It would beep and flash.
• When they reached 187 feet, they would have gotten another set of beeps warning them that the oxygen was at the maximum safe limit of 1.4 atmospheres of pressure
• Most computers have a depth alarm that would have warned them about exceeding depth limits
• Many computers have turnaround alarms that will warn you when you have used a third (or some other programmable amount of your air) of your breathing gas
• Many dive computers would have had their models exceeded and would go into “violation” mode. There are more alarms here, and the computer only functions as a digital set of gauges after that point.

In short, there is no way that dive was an accident, and that is not even considering the stupidity of swimming that far into a cave. It always astounds me that someone will pay a thousand dollars for an expensive piece of gear that’s designed to save your life, then will ignore that device. The cheapest dive computer can be bought for less than $100 (although I wouldn’t bet my life on cheapest.)

My dive computer cost me well over $600, but it is obsolete and no longer for sale. If I were to buy one today, I would want a gas integrated console computer that can handle multiple gas mixes on one dive. The small wrist ones aren’t readable by this old man’s eyes- the numbers are too small on the display and I don’t want to wear a prescription dive mask.

So with that being said, I would want:

• gas integrated
• nitrox capable to 100%
• multiple gases on one dive

With that, I my research settles on these:

• Apeks DSX Dive Computer:The nice thing about this one is it would let me upgrade to trimix if I decide to do that in the future. It’s pricy though: $1200. Also, the connection to your tank is wireless, and that means sometimes losing the signal and not knowing how much pressure you have left.
• Mares Genius: This one is cheaper at $800. Still has the wireless connection issue.
• Oceanic Pro Plus X: This one solves the wireless issue, but it only handles nitrox to 50% and can’t do trimix. It’s also pricy at $1200.

I’m sure there are others, but those are the ones I would consider.

The disclaimer: I don’t advertise, and receive nothing for my reviews or articles. I don’t think that I ever will. I have no relationship with any products, companies, or vendors that I review here, other than being a customer. If I ever *DO* have a financial interest, I will disclose it. Otherwise, I pay what you would pay. No discounts or other incentives here. I only post these things because I think that my readers would be interested.

From la Repubblica, a story of the deceased divers from the Maldives. A Finnish team managed to recover the final two deceased divers yesterday. All four of the remaining divers were located in the same chamber, more than 200 feet below the surface, and more than 300 linear feet inside the cave. The rescue team has given some insight into what happened to the missing divers. To understand what happened, a map of the underwater cave.

This is a diagram of the cave system, as seen from above, looking down. The divers entered the cave from the right, off of the frame.

The divers entered the cave system at a depth of 180 feet. The cave begins with a first large, very bright cavern with a sandy bottom. It would seem enticing to go further, as this looks very inviting.

They swam through a connecting tunnel from the first chamber to the second. This connecting tunnel is almost 100 feet long, ten feet across, and just three feet tall. It led to the second chamber of the cave, which is a large, round space with no natural light. This second chamber had a depth of over 200 feet. The interior of this chamber would be completely cut off from daylight, and the only visibility would be provided by any handheld lights that the divers had brought with them. The inside of such a chamber is a confusing jumble of rocks, with one rock looking much like any other rock. Even though the water in here was clear, it was a dark, confusing maze of rocks and sand.

At some point, they entered the third chamber (which was a dead end with no way out) through another tunnel whose entrance was right next to the connecting tunnel leading back to the first chamber and the exit. The Finnish team notes that the exit tunnel’s opening was partially obscured from view from the vantage point of a diver in the second chamber by a large pile of sand. It is easy to get over the sandbank into the second chamber, but when you turn around to leave again the bank almost looks like a wall, hiding the corridor from view. The team believes that the divers mistook the tunnel leading to the dead end and their literal death for the tunnel that would lead them to safety.

The divers were only equipped with 80 cubic feet of breathing air. At 200 feet, they would breathe through that supply at 7 times the rate of the surface. By the time they had penetrated the cave to that point, they likely had a minute or two of air left before they all drowned from lack of air.

This reinforces my opinion of what I think happened. These divers were diving beyond their training, experience, and equipment. Had they been properly equipped and trained, they would have stretched a guideline as they went and wouldn’t have gotten lost. They would have had more than just 80 cubic feet of breathing gas, and they wouldn’t be dead.

This was diver error, plain and simple. As I said before, the ocean is an outright jealous bitch, and she shows no mercy to those who do not give her the respect she deserves.

EDITED TO ADD

One of the things that gets me, although it shouldn’t at this point, are the social media experts who are claiming this team had tons of training and experience, so something else must have happened. I have seen theories ranging from “they had bad air” to rogue currents (although how a current runs through a dead end cave, they don’t explain), and even one that claims they were drug there by a large squid to be used as food.

I am not the only experienced diver who actually knows better. It doesn’t take any special disaster to have made this happen- just a combination of inadequate training and experience combined with arrogance of Dunning Krueger and a dangerous environment with a very small margin of error, and that’s all you need.

The SCUBA tragedy in the Maldives has another interesting turn, and one that actually supports my belief that the divers were diving far beyond their training, equipment and experience. The bodies of the four missing divers have been recovered, and they were located in the third chamber of the cave at a depth of 200 feet.

The Italian tour operator that manages the Maldives diving trip denied authorizing or knowing about the deep dive that violated local limits, its lawyer told Italian daily Corriere della Sera on Saturday, according to an AP report.

Orietta Stella, representing Albatros Top Boat, said the operator “did not know” the group planned to descend beyond 30 meters. Crossing that threshold requires special permission from Maldivian maritime authorities and the tour operator “would have never allowed it,” she said.

I want you to look at this short video of the equipment that the dive team is using to recover the bodies.

This setup is called a rebreather. It works by having the diver rebreathe the air in his lungs over and over again. The device removes CO2 from the exhaled air and adds oxygen as needed to maintain a safe mixture. These devices are the gold standard for diving at the edge of human physiology. This is closed circuit diving, and rebreathers are specialized equipment, costing tens of thousands of dollars for each.

Now consider what the divers who died were equipped with:

The Italian divers were experienced, but the equipment used appeared to be standard recreational gear rather than technical equipment suited for deep-cave diving, she said.

This is the part that I can’t confirm, but this is reportedly the cave where the group was diving. Even if it isn’t the exact same cave, this is what it would look like. These caves are covered in fine silt, and one wrong move, one errant fin kick sends that silt up into the water of the cave, reducing visibility to zero.

One of the things you do in an area where visibility is potentially poor is use guidelines. A guideline is a rope that leads you back to the exit. Firefighters, rescue personnel, and cave divers are all familiar with this. The line has markers on it to indicate direction so you don’t accidentally follow the line in the wrong direction. It looks like this:

The round markers are called cookies, and the arrows are called, well, arrows. These shapes are easy to identify by feel in cases where there is no visibility. The arrow is placed on the line so it points to the exit. Unlike arrows, which explicitly point toward the nearest exit, cookies are round and do not point anywhere. They are used to mark other things. For example, if a cave branches off in different directions, the guideline will as well. So you use a cookie to mark which of the guidelines the team followed to go deeper into the cave.

In this case, it is evident that the divers didn’t use guidelines. They weren’t equipped for deep or decompression diving, and none of the divers involved were trained for this.

When that visibility is zero, you are weightless, it’s very disorienting. If you don’t know what you are doing in a cave, this is a death sentence. You have about 3 minutes to figure it out, or you and everyone with you in this cave is dead. That’s how 5 divers can die all at once. My guess is that this is what happened, and one of the divers managed to make it as far as the cave entrance before his air ran out. This has been my belief all along, and nothing I have seen to date contradicts my belief.

Now that the bodies have been located, the plan is to recover two of them tomorrow, and the final two on Wednesday.

I love how the readers of this blog have such a depth and breadth of experience. Nothing illustrates that more than the SCUBA discussions we have been having. I keep my gear as simple as I can, both because I want to manage the dive, not my gear, and the simpler your gear, the lower the odds for a malfunction. Let me explain my setups:

Buoyancy Compensator

My BC is one I made myself. There was a custom metal shop in Pennsylvania that made custom backplates out of solid stainless steel. The company was called Hammerhead SCUBA. They have since gone out of business. The plate and tank adaptor, pictured below, weigh in at about 12 pounds.

To that, I added a single length of seatbelt webbing wound through the plate, making it into both a waist belt and shoulder straps. On the waist belt, there is a single pouch for adding a single soft weight, so I can use it to adjust buoyancy for things like thicker wetsuits. Also on it are numerous stainless steel d-rings so I can attach various things to my gear when needed.

Also attached to the backplate is an OxyCheq wing with 30 pounds of available lift. They are great wings, and in over a decade of diving, I actually wore one of them out and they let me buy a replacement at 50% off. Great company.

To make things comfortable, I also put a back pad in it. This also created a pocket of sorts that is the perfect place to hide a folding dive flag for when I am on the surface and want to be seen by nearby boats.

Regulators:

I have two Aqualung Legends, one with a DIN connector and one with a Yoke. The yoke connector fits my pony bottle. I also have an older Mares regulator that I sometimes use, there is a DIN fitting on it, and the two DIN regulators I have are tuned so that when you take a good breath on them, they practically force air down your throat. When I am working hard, I want there to be no feelings of being air starved. I have a mechanical pressure gauge on all of them, as well as a QD hose for my dive computer, which allows me to move the computer easily from one regulator to the other, if needed.

Computer

I went through a few computers before I found one I really liked. I tried the wireless ones, and didn’t like them. They lose connection to the pressure sensor too easily. My favorite computer is the Oceanic Pro Plus. Also, it has large numbers that are easier for this old man to read without glasses than is a wrist mount computer. Other advantages are that it allows me to change between three different gas mixes on the same dive. I’ve had great luck with this computer- it served me on hundreds of dives with no issues, including the occasional decompression dive.

Tanks

For tanks, I have a pair of 120 cubic foot high pressure steel tanks, and another pair of 100 foot tanks. I like the 100 foot tanks better. They are 11 pounds negative when full, 2 pounds negative when empty. Using this and a steel backplate enables me to dive without using a weight belt. With this configuration, I am neutral at 10 feet of sea water and an empty tank. Perfect buoyancy. I only accept EAN from companies that blend. I will not use banked EAN because I have had too many issues with contaminated gas from them.

I also have a 19 cubic foot aluminum tank that I use either as an emergency supply or as a deco tank. As a deco tank, I fill it with EAN80, as an emergency tank, it either has air or EAN32.

The rest of it

Completing my setup, I dive with 36 inch freediving fins, because I find that a long stiff fin allows me to drift and steer with little effort but also lets me take advantage of strong leg muscles and really get some speed on. I wear a pair of diving shorts with pockets, so I can store a lift bag and thumb reel with 100 feet of line in one pocket, and a rechargeable flashlight in the other. Attached to my waist belt is a short 4″ dive knife. No snorkel, none of that other extraneous stuff that isn’t really needed, just a simple mask. Too many divers buy a ton of crap that they don’t need, then look like they are wearing half the dive shop while they are in the water. All that does is create drag and weight, which slows you down and causes you to use more gas.

Diving for (Almost) Free

At first, my girlfriend at the time and I used to maintain a website that was a list of dive spots and boats in Florida. We would review all sorts of sites and boats. That’s why my internet handle is divemedic. The site is gone, but it was fldiving.com, and once a boat or shop found out you were running a website for divers, you got all kinds of free stuff. Then my girlfriend and I split up, and I let her keep the website. It lasted a year or two longer, then it disappeared. I guess she didn’t keep up with it.

After that, I spent a few summers working as an underwater dive guide. You don’t make any money at that. What you do get to do is dive for free. Get on the good side of a local dive shop, especially near a tourist area. Florida does some odd things diving that people up north aren’t used to. One of the things we do is drift diving, which other places really don’t do. Tourists want someone to walk them through it, so the dive shop gives them your name and number. They call, and you recommend a boat. There are boats that know my name and offer to let me dive for free if I bring at least three other divers with me. The tourists make the reservation with the boat and pay for their dives and give the boat your name. It doesn’t cost the tourist any extra money for my services, they get a guide who makes sure they have a good time while being safe, and the boat gets some business for the price of an extra diver that costs them nothing. Everyone wins.

When it comes time for the dive, you help them get set up on the boat, then right before we all jump in, I would check their gear to make sure it was setup correctly. After that, all I had to do was throw on the BC and mask, jump in the water, pull on my fins, and I was good to go. This setup is very quick and easy to get into and out of. Fitting these dive trips into my fire department schedule was easy, and I would spend the summer getting in as many as 50 or 60 dives a month. One summer, I hit almost 200 dives from June through August. The most dives I have ever done was a two day period when I did 10 dives between 60-110 feet in just two days. All free.

I would guide my tourist puppies through the dive and get them back to the boat. Sometimes they would tip, sometimes not. I didn’t care. All the tips did was pay for the gas and tolls to get from Orlando to West Palm Beach, Pompano, or Boynton Beach, those being the locations of my favorite dive boats.

The drift diving here is fantastic. The boat drops you on a reef one or two miles offshore, with the bottom being 55-110 feet below, depending on which reef you are diving. For tours, I used to seek out 55-65 foot deep reefs so I could dive it on EAN36 without an issue. The leader (me, when I was the guide) tows a buoy with a dive flag on it using a rope. The divers drift with the current along the reef. You can see a tremendous amount of interesting sea life. At least one or two sharks on every dive- most of the time, you will see even more. Occasionally, you see a really large one- 8 feet or more. During the summer, water visibility can vary from 20 feet all the way up to being able to see the dive boat while on the bottom at 80 feet. On those days, it’s like swimming in a glass of gin.

The limit for the dive is when the first diver in the group hits 700 pounds of gas remaining, a diver hits his NDL limit, or we have been in the water for an hour. I would then have the entire group surface with me. We would spend an hour on the boat, change tanks, then do a second dive. In all, we would spend about 3 or 4 hours on the boat. I would use the rinse hose and some baby shampoo to shower on the back of the boat while we were headed back to shore. Sometimes, I would take a vacation or sick day and spend a week diving every day.

Those were my best days of diving. I spent my summers (this was about 2 years after I divorced my first wife) SCUBA diving. I was great- my tan was awesome. I can see the allure of being a beach bum. It was amazing. I got over 2,000 dives in less than 3 years, averaging more than one dive every calendar day.

One of the boats used to joke with me, because I once spent over an hour and a half on a 60 foot dive and he was pretty pissed. I pointed out to him that he said “dive the limits of your computer or until you are at your reserve air pressure.” Not my fault I have great SAC, a 120 cubic foot tank, and was breathing EAN36.

After that day, the captain would drop my buddy and me in the water first, motor off some distance to drop the rest of the divers, pick them back up, then come over to get me. He was a nice guy. Near as I can tell, his boat is no longer in business.

During the efforts to recover the bodies of the four divers whose bodies still haven’t been found, one of the military divers has died of decompression illness. As a result of this latest fatality, the Maldives government is suspending body recovery operations until experts in deep and cave diving can arrive on the scene, perhaps tomorrow.

The woman who was the defacto leader of the group is being called an “expert with over 5,000 dives.”

Ms Montefalcone’s husband, Carlo Sommacal, told Italian outlet La Repubblica that his wife was an “expert” and had done 5,000 dives.

I can’t stress how difficult and dangerous this dive is. As I said in the other post, my experience and certifications are remarkably similar to hers, and I am telling you now that I am not, and she is not, in any way qualified to do that dive, nor was she equipped to perform that dive. I know I am not trained or equipped for it. In addition to being NAUI and PADI certified as a divemaster, rescue diver, nitrox, public safety diver, and cavern certified, I am also SSI certified for extended range diving and extended range nitrox. (the first two classes in this list.)

The reports I am seeing is that her group of 5 divers were diving ordinary open circuit with single aluminum 80 cubic foot tanks. That is not the way to do this, and she should know better. It is my belief that Dunning-Krueger is in full effect here- she was making the assumption that all diving is the same, so diving to double the recreational limit is no big deal, and basing that on her training and experience in shallower depths- perhaps thinking her professorship and TV fame made her smarter than everyone else.

The issue with this latest death, is that the Maldives military is no better. It’s being reported in SCUBA circles that the military diver was in recreational gear with single tank and an extra slung aluminum 80. That is nowhere near good enough. The entrance to that underwater cave is at 160 feet. The caverns that are being searched are at 200+ feet.

• There is no safe limit for diving to that depth that doesn’t require decompression.
• Nitrogen is intoxicating at that depth. This compounds the danger, and requires mixed gases, especially as you approach 180 feet or deeper.
• Oxygen in normal air becomes toxic when breathed at depths greater than 185 feet.

For the reasons above, dives to that depth require what’s called hypoxic trimix, a mix of 10-16% oxygen, 50% helium, and the remainder nitrogen. That mixture avoids the risks of OXTOX, narcosis, and lessens the issues with decompression sickness. The issue is that hypoxic trimix can’t be breathed on the surface or at shallower depths. This means a diver has to have what’s called a transit gas, usually trimix with 21% oxygen, to get from the surface to about 150 feet or so. Then there are decompression gases needed, which can include 50% nitrox or other gases. The exact depth for each gas and when to switch depends on the chosen mix, target oxygen pressure (1.2–1.4 atmospheres), Equivalent Narcotic Depth (END), and the decompression plan. The people who do this always use gas and dive planning software. This isn’t the sort of dive where you just dive in and go for it.

In all, a dive like this could require every single diver to enter the water with 4 or more tanks, and still be required to use a surface supplied decompression gas. In many cases with a dive like this, divers will go in ahead of the search team and bring in full tanks of trimix that are left in staging areas within the cave. It’s a very complex and dangerous operation.

Now multiply that by the number of divers you need- this will include the search team, support divers who don’t enter the cave but assist the search team in managing the dive at depths from 150 feet up to the surface, the divers who penetrate the cave to set up staging tanks, then there is a medical team, and other members.

Each diver who enters that cave will have about 25 minutes to conduct the search, then will spend the next two hours working their way to the surface as they decompress at progressively shallower depths. Total run times of 3+ hours are common, with significant stops on 50% nitrox and pure O₂ required to decompress.

In all, an operation like this will take a dozen or more people and cost over a million dollars.

Or you could just cancel the entire useless exercise and leave the dead where they lie. Why risk creating more bodies? My opinion is leave them where they are. They are already dead, and any potential benefit in recovering the bodies isn’t worth losing yet another life. If the Italian government or the family isn’t happy with that, they can mount the expedition, with the understanding that any other death will result in the supervisor of that dive being charged with negligent homicide.

The ocean is an unforgiving bitch if you don’t show her proper respect.