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As mentioned previously, a great way to more accurately monitor dive times and to track nitrogen loading during your dive and surface interval is to use a personal dive computer (PDC). Modern PDCs are helpful and easy to use, but there are a few rules and safety tips relating to PDCs and how to use one.

  • Follow established safe depth limits, and dive times must remain within NDLs.
  • Ascend slowly to allow plenty of time for the nitrogen to outgas, recommended 9 meters/30 feet a minute.
  • Follow the PDC's required safety stops.
  • Ensure the correct gas mix is loaded into the PDC, even if it is normal air.
  • Make a 3- to 5-minute safety stop at 5 meters/15 feet, or follow the required stops displayed by the PDC.
  • Even after additional training and experience with deeper dives, limit repetitive dives to 30 meters/100 feet or shallower.
  • Ensure you read and understand the manufacturer’s guidelines on the use of the PDC, or have an experienced operator show you how to use it.
  • Maintain good cardiovascular fitness.
  • Never dive dehydrated. Drink sufficient water at least one day before diving and during your diving adventures.
  • Allow extra surface interval time between dives if possible.
  • Allow 12 to 24 hours before you fly in a commercial airplane after diving, or follow the no-fly dive time displayed on your PDC.
  • It is strongly recommended that divers limit their depths to their certification level or the depth calculated by the PDCS—whichever is more conservative.
  • Divers within the recreational program range should ascend before any required decompression stops are required. Decompression diving requires specialized training, equipment, and procedures.
  • Perform pre-checks. Turn on the PDC. Check all the functions to make sure that device will work properly. Always check battery energy levels.
  • A PDC should never be shared among divers.
    • Your physiology changes every day. PDCs and dive tables can help you determine how long you can dive. But they do not take into account how your body functions each day. It is almost impossible for two divers to have the same dive profile. They will often have different surface interval times and different previous dives. Therefore, sharing a PDC is dangerous. And it can lead to symptoms of DCI.
    • If you complete a dive without your PDC, refer to the PDC manufacturer’s guidelines. All the dive information contained within the PDC will be incorrect.
  • When diving with nitrox, make sure the analyzed value of the gas in the cylinder is entered into the PDC. You should also obtain the correct training for nitrox diving by attending a nitrox specialty program.
  • Select the correct altitude adjustment setting. Altitude diving is considered to be any dive greater than 300 meters/1,000 feet above sea level. Many PDCs automatically adjust to altitude. However, consult the manufacturer’s guidelines for adjusting your computer for altitude. If you fail to set the correct altitude, your PDC will give you incorrect information. This can lead to serious injury and symptoms of DCI.
  • In general diving and when first starting out, select a conservative setting. Later, you may adjust this setting to be less or more conservative. Dives can vary greatly. They can have different workloads, temperatures, durations, etc. Being able to change how conservative your PDC calculations can be is important. You can take into account what kind of dive you are doing. This adjustment will make the dive safer. And it may reduce your chance of getting DCI. Refer to the manufacturer’s guidelines for help.
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