One aspect of any technical diving class should be the use of bottom stages. Bottom stages are used either when a diver’s doubles are not big enough for the dive and additional bottom gas is needed to perform the dive or when a diver would like to do multiple tech dives in one day. This saves backgas to be used on the second dive. To perform the safety drill, or S-drill, is very similar to that with the long hose, but there is a couple added steps. This article will try to clear up the steps used to perform a S-drill with a bottom stage.
In theory, one should never go out of gas in a bottom stage and backgas. Prior to getting into the water, the team should verify gas and deploy the stage regulator. Bottom stages are used at the beginning of a dive. Once the bottom stage is spent, the diver switches to backgas. It is possible for the diver to have a leak somewhere in the doubles and when the bottom stage is spent, finds no gas left in the doubles. Thus, needing to share gas with a buddy. The DIR method of sharing gas is to always donate the regulator from the mouth. This ensures the OOG diver is getting a regulator that works, has gas, and is breathable. We do not waste precious seconds searching around for a regulator in a pocket or clipped off somewhere.
When practicing s-drills with bottom stages, the procedure is the following:
1- The OOG diver signals out of gas. The donor donates the stage regulator from the mouth to the OOG diver.
2- The donor diver then switches to the necklace regulator.
3- At this point, we must make sure the OOG diver is OK and sort out the problem. In a real OOG emergency, when there is no gas in the stage or doubles, the team needs to determine the exit strategy. When practicing the stage s-drill, we assume the OOG diver does not have any gas remaining.
4- Once the OOG diver has signaled OK, the donor diver then unclips the long hose and donates the long hose to the OOG diver. Clearing the long hose from the canister light, making the long hose fully deployed.
5- The OOG diver switches from the stage regulator to the donors long hose and gives the stage regulator back to the donor.
6- The OOG diver is now on the long hose. The OOG diver and the donor stow their respective stage regulators back on the stage bottle.
7- At this point, we can cut the s-drill, assuming this is not a real OOG situation. The team can then go back onto the bottom stages. The OOG diver then signals “watch me, gas switch” and switches to the bottom stage. Then gives the long hose back to the donor.
8- The donor then replaces and clips off the long hose. Once the OOG diver switches to his/her bottom stage, the donor can then switch to his/her bottom stage.
9- Continue the dive
The primary focus should be on slowing things down and looking at the big picture. When slowing down each step, the divers can then make well-thought out decisions. The procedure to switch to a stage or deco bottle has already been discussed in a previous article, Gas Switching Procedures. If you are planning on doing dives with bottom stages, you should practice the s-drill with stage bottles frequently. This drill should most certainly be taught as part of any technical diving class.
This article should not replace sound dive training. If you are not properly trained in gas switching procedures, you should avoid using bottom stages.
Dive Safe,
Duane
Precision Diving
