By Andrea Zaferes
The following article addresses the needs of teams who have water with low to zero visibility in their district with depths up to 60 feet, which includes almost all teams around the world. The majority of the equipment discussed also applies to high visibility operations. Additional equipment is needed for deeper dives. Surface supplied gas should be used for dives below 100 feet.
The NFPA rightly designates water as a hazardous atmosphere because it cannot sustain life. Hence, breathing gas becomes the most important ingredient to staying alive underwater, and the equipment that provides it to us is top on the list for what we need to be able to go home.
Cylinder size and valves
In regards to size, 80 cuft/3000 psi aluminum cylinders work well. Unless the team has all the gear that is needed and has money to burn, steel cylinders are not necessary. Nor are DIN valves, which significantly raise the cost of cylinders and regulators. Unless the team does much work inside vehicles and has a large budget, K valves will work just fine. We have never seen a regulator knocked off a K valve in over 20,000 dives with many vehicle dives. In regards to steel cylinders, divers should not be using up so much air that the buoyancy changes in an aluminum tank should be detrimental. And so what if your tank is a steel 80 cuft/3500 psi, it still only has 80 cuft of air. It hurts to meet a team talked into spending thousands of extra dollars on steel tanks with DIN valves, and now do not have the funds to buy really necessary equipment like pony bottles.
Quick-release Pony Bottles
Can a regulator fail? Yes, and if it does, and is a downstream regulator like it should be, then it will fail open and will freeflow, thereby rapidly depleting your air source. Could the first stage freeze open and empty your cylinder in less than a minute in cold water? Absolutely. Could you become entangled, thereby extending the planned dive time? Sure. Could your pressure gauge blow off its hose, or could an air hose rupture? Yup. What we’re getting at here is that having one air source is not enough. This is especially true for PSD divers because entanglement is a very realistic risk, and because well-trained teams know that solo-tethered-tender-directed divers are far more effective, accurate, and safer than buddy teams or worse, multiple-diver line searches.
Being solo means needing to be self-sufficient, which means a pony bottle is required. Even if you are using the recreational buddy-dive techniques, a pony bottle is still required. A diver is entangled, and the buddy or backup diver passes of an octpus. Great, now what do they do tied together like that? How can the buddy work on the entanglement? And worse, buddies dive at the same time so if one diver is low on air, so probably is the other diver. Great plan. To show that few divers have realistically tested this octpus plan, close your eyes and pass of your octopus to an entangled diver. Now, which direction can you move to assist the diver? If you have to think about it, then it isn’t practiced well enough. If you do not understand the question, then chances are you have not even realistically tried the skill, because if you had, you would know that if you move in the wrong direction, the octopus will be pulled out of the diver’s mouth.
How anyone can dive on the bottom without a backup air source is incomprehensible. Worse, we repeatedly hear, “we don’t use pony bottles because they are an entanglement risk.” Well, if you think for a minute that entanglement is a potential then how dare you not dive with a secondary air source?! Ironically, those same divers never seem to have have their fin straps taped, their gauges secured trimly, and their BCD power inflator hoses secured under their arms, which all decrease entanglement risks. Often they dive with snorkels and knives on their legs, which both increase entanglement risks, and they rarely have three cutting tools that they routinely practice with. To add to the illogic of this too common attitude, properly worn pony bottles are far less of an entanglement risk then the above mentioned hazards.
Some teams move away from the sport diving octopus mentality and go towards recreational technical diving with the result that twin main cylinders are worn. Better, yes, but twin cylinders do not allow divers to pass off an air source, and for the 20-25 minute dive times shallower than 60 feet, they are a costly, cumbersome, and unnecessary. Quick-release pony bottles allow divers to ditch their BCD-tank assembly and still have an air source.
A PSD in NJ diver became so entangled in a gill net on a sport dive after losing his buddy at the end of the dive, that the best solution was to ditch his BCD-tank assembly, remove the pony bottle, and make a controlled ascent to the surface. Without that quick-release pony bottle his 100 foot ascent would have been without air and there is a good chance he would have died. In PSD, backup divers can pass off their quick-release pony bottles to entangled, low-on-air primary divers. The backup then goes back for a replacemenet pony and the contingency 80 cuft tank. As long as the primary diver has air, entanglement is a manageable problem.
Hence, quick-release pony bottles of at least 19 cuft should be mandatory. If many dives are in the 40-60 foot range, choose 30 cuft bottles. Quick-release systems can be as simple as a webbing harness, can be as slick as a TigerGear™ metal system, or can very effectively be part of the BCD. Having the pony is not enough though. Frequent, realistic training is as is important. Also, divers should surface on their pony bottle at the end of training dives to make switching to the pony reflexive anytime a diver needs to surface. Otherwise, the pony just becomes a piece of gear worn with a realistic chance that when it goes bad, a panicked diver will not think about using it.
Full Face Masks
If you have known or potential contaminated water, then do not bother purchasing standard regulators. Go right for hazmat tested full face masks such as the Interspiro AGA™. Are they more expensive? Sure. But if you would not sit down with a glass of the lake water and have a drink, or if you plan on performing submerged vehicle operations, then don’t go in without full face personal protective equipment (PPE). Start out right, or not at all. If you start out with shortcutting, it will be hard to get what you need later as your chief says, “you’ve been diving that way for years and no one has gotten sick, so why do you need new equipment now?” As an officer of the Fort Wayne (IN) FD did, offer a pitcher of river water to the budget decision makers and see if they’ll drink up.
If contaminated water is a reality then removing the full face mask to access pony air is not a safe option.Walt Hendrick wanted a block with two features for PSD: The block needs to allow a backup diver to replace the primary diver’s pony with a fresh cylinder. Additionally he wanted a block that was mounted on the full face mask such that the hand motions of a panicked diver to rip the mask off would hit and activate the block, thus providing the diver with pony air and turning panicked behavior into lifesaving behavior. Carl Seiba of Sartek built the RSV-1 in response to those needs.
Air versus Nitrox
What about nitrox instead of air as some dive stores attempt to sell to PSD teams? Nitrox is a breathing gas oxygen-nitrogen mix most commonly associated with an oxygen percentage higher than twenty-one percent designed to decrease the risk of decompression sickness if air no-decompression tables are used. If dive teams use the maximum depth of 60 feet and maximum dive time of 20-25 minutes, then decompression sickeness is not a concern. Second, there is no research to support the popular belief that nitrox decreases fatigue. Improper use of nitrox, such as diving it at too great depths, can result in far greater consequences than making a mistake on air. Nitrox is much more costly than air because of additional training, tank fills, and compatible regulators. Less than ten percent of PSD divers can calculate their surface air consumption rates, yet now they are going to make nitrox calculations? With the too few training hours and dollars devoted to most PSD teams, nitrox is not recommended.
Take the time to think about all the things that can go wrong and do whatever is possible to prevent them, and have proven, well-practiced contingency plans to manage the problems should they occur. Not having a breathing gas is certain death underwater so that is the first and foremost consideration. Begin with having the right equipment such as quick-release pony bottles, and if the water is contaminated or very cold, use full face masks with PSD blocks. Find out edatingcafe to get charming for women. The next step is realistic training. Future articles will discuss other necessary diver and tender PPE. Questions and comments are welcome at email@example.com.