Decompression stops, whether simulated or actual, are an integral part of most technical diver courses. We generally associate decompression with holding on to a line while staring off into space. However, if that is all your students do during deco, you may be missing out on several valuable learning opportunities.
Here are four things you can have students do during deco that will greatly enhance the learning experience.
1. Measure gas consumption
Knowing your Surface Air Consumption or SAC rate is critical when planning technical dives. Without it, you have no way of determining how much gas to take with you. Bear in mind, your students need to know both their working and resting SAC rates.
Working SAC rates apply any time divers will be swimming, pulling against current or otherwise exerting themselves.
Resting SAC rates apply any time divers aren’t moving or exerting themselves. In other words, during deco.
As with working SAC rates, it is not sufficient to measure gas consumption just once. Divers need to measure their resting SAC rates several times, under varying conditions. They then need to average the results to arrive at a more accurate overall value.
If your students have not yet done this, make it part of their training.
2. Practice emergency skills
In good conditions, decompression stops can provide an excellent opportunity to practice vital emergency procedures. Examples can include dealing with situations such as:
Mask loss (switching to backup mask)
Loss of deco gas (buddy breathing with a single deco cylinder)
A free-flowing regulator (manifold shut down)
You could brief what skills you intend to have students practice prior to the dive; however, doing so would eliminate the element of surprise. In the real world, divers seldom get prior notice that a problem is about to occur.
To make emergency skills practice more realistic, TDI offers Decompression Instructor Cue Cards. These compact cards come in a set with a stainless ring holding them together. To use them, you simply select a card and hold it up, so students can see it. They then have to respond appropriately to the situation appearing on the card.
Be aware that some emergency situations may be best practiced on simulated deco stops rather than mandatory ones. That way, if there is a serious problem, students can ascend without risking DCS.
While we most often associate decompression with holding on to an anchor or ascent line. This is not always the case. Divers in lakes, quarries and similar sites may do their decompression along walls and slopes.
In this case, there is no need to stay in one location while decompressing. Divers can swim slowly along the face of the slope or wall, while maintaining a constant depth. This can provide the opportunity for further exploration, or to continue to shoot photos or video. Doing so is a lot more fun than simply holding still.
4. Do nothing
Wait a minute! Haven’t we been saying that not having students do anything during deco wastes a valuable learning opportunity? Generally speaking, yes. But there are times where doing nothing can provide a valuable lesson in and of itself. This can be especially true during the early phases of Decompression Procedures training.
Students in a Deco Procedures course have typically not done anything more than a three- to five-minute safety stop. They don’t know what it’s like to hold still and do absolutely nothing for ten minutes or more. By having them do just that, and discussing it later on, you can teach a valuable lesson. That is, it’s not a contest to see just how much deco you can do.
The goal in technical diving should always be to do only that decompression which provides an adequate safety margin and minimizes the risk of DCS.
When your dive-planning software shows that five extra minutes of bottom time will only result in two minutes of additional deco, it may reflect a worthwhile trade-off.
However, in situations where that same five minutes of extra bottom time could result in five to ten more minutes of decompression, you have to ask whether or not it is worth it.
Having students spend a lengthy deco stop doing essentially nothing helps underscore the point that decompression is boring. It’s not something you want to do unless the rewards make it worthwhile.
Make deco time learning time
No matter how long your courses, you most likely wish you had more time for students to learn. It makes sense, therefore, to ensure you use the time you have as productively as possible.
Before your next course, plan how you can turn every deco stop, whether simulated or actual, into a learning opportunity. Your students will find this more enjoyable — and you will have the satisfaction of knowing you helped better prepare them for real-world diving.
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