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By the end of this topic, you should be able to answer these questions: 1 What is the purpose of a checklist and how can you use one? 2 What does a technical diving predive check cover? 3 What are the main elements of a predive safety check? Predive Preparation Predive preparation is often more complex in technical diving so many tec divers use a checklist to avoid missing anything. When used correctly, checklists have been extensively proven to reduce errors in procedure in fields that require technical precision such as aviation and medicine. In scuba diving, checklists exist for recreational divers, but have more recently been popularized by rebreather divers and are now widely used by all tec divers. image placeholder for 730x365 As you get ready, follow the checklist as a prompt. Use the tick boxes to check off items/tasks as they are completed. You need to use your checklist consistently on every dive. Tec Diver Predive Checklist You’ll find the Tec Diver Predive Checklist in your PADI Tec 40 Diver eLearning Resources. The checklist covers the minimum requirements, but some dives may have additional requirements that you'll want to note. The checklists prompts you to: Analyze cylinders – personally analyze/re-analyze all cylinders prior to assembly and verify that they are labeled correctly. Check that the isolator is fully open (if applicable) before analyzing. Assemble equipment – ready to don with cylinders fully opened. Breathe all regulators – check for adequate function and ease of breathing. Pressure test Wings/BCDs – test one at a time if using a double bladder, and leave each inflated for a few minutes. The wing/BCD should remain fully inflated, otherwise there is a leak. Positive pressure test regulators – check the SPG reading, close the cylinder valve and leave for a few minutes. The SPG reading should not fall, if it does there is a leak. Negative pressure test regulators – with the cylinders still closed, breathe the regulators normally until flow stops. The SPG should read zero and gas should not flow or creep through the regulator. Check SPG gas pressure – turn on cylinders again, check that your isolator is fully open (if applicable), and confirm adequate cylinder pressure. Turn deco/stage cylinders off, but leave pressurized. Note turn/minimum ascent pressure – write it on your wetbook/slate (if not already done) and confirm with team mates. Don and adjust equipment – check/turn main cylinders on again before donning equipment. Any item that fails the checks must be fixed before the dive. Do not dive with equipment that has any kind of a problem. Sometimes small leaks can be fixed on site, but many wing/BCD or regulator leaks will need a qualified service technician’s attention. Do not dive with leaking equipment. Having spares available (often as a team) or the ability to quickly obtain replacements is a good idea whenever possible. Turn Pressure Calculation Your turn pressure is the gas pressures at which you turn the dive and head back. In areas where the water temperature is higher than the air temperature, you may recalculate turn pressures at the surface after cylinders have adjusted to the water temperature, otherwise your turn pressure may be too low. This won’t affect minimum ascent pressure calculations. More on gas reserves later in the Gas Reserves section. Predive Safety Check As in recreational diving, you do a predive safety check before each dive. A tec diving predive check is similar to the one you perform in recreational diving, only more extensive. Your predive check is your final gear and readiness check before the dive, so it’s important to be thorough. image placeholder for 730x365 Photo credit ScubaPro Head-to-Toe Matching With your team mates you check and match equipment from head-to-toe looking for loose or missing gear. Check equipment function, where applicable, placement and accessibility of equipment as well as confirming familiarity with your team mates' equipment. Different teams and dives may require additional equipment and the order may vary depending on configuration, but as a minimum your predive check should include: Hood – check placement Mask – should be prepared and ready to don or already donned Regulators – check that the longhose is free to deploy and that you can breathe from each regulator Cylinder valves – check that cylinder valves are open on your bottom gas and bailout gas (if carried). Deco/stage cylinders should be pressurized, but closed. Wing/BCD inflator – check functionality including oral inflation. Check placement and accessibility of any backup inflators. Dry suit inflator – check that the connection is secure, the inflator works and suit inflation cylinders, if used, are open. Check placement and accessibility of any backup inflation hoses. Dive computer/timer(s) – check that they are turned on, have adequate battery life, are set to the right gas(es) and any other parameters are correctly set Weights – check all weights have been donned and any releases are accessible Wing/BCD dump valves – check function and accessibility. Dive lights – turn on primary light and leave on, if possible. Check that backup lights work and are stowed correctly. Backup mask – use defog to make sure it will be ready to use. Stow it and make sure it is easy to retrieve without looking. Two divers access thier gear. Photo credit Alfred Minnaar/Fourth Element Additional Equipment Other equipment should be easy to reach and accessible: DSMBs/lift bags Reel(s)/spools Cutting tools Surface signaling devices such as whistles, mirrors, etc. Wetbooks/slates and pencils Check any additional equipment being used for the dive, for example, cameras. By using the head-to-toe method you check and match equipment, but keep in mind that if everyone in the team forgets something, this check won’t catch it. While it’s very unlikely everyone will forget the same thing, you should be aware of the possibility. Use the predive checklist to ensure you have covered all the essentials.