'deep stop' experiences

[ark7750]

For either rec if tech, if you have the option to set you computer for a "deep stop" do you feel less tired at the end of a dive? Maybe this is too subjective of a question to post.

 

[Belzelbub]

I turn that option off. For the most part, Deep Stops have fallen out of favor in recent years.

The main issue is that for many dives deep stops have the slower tissues on-gassing during the deep stop, so those tissues end up with more absorbed N2 than a similar dive without the deep stop.

 

[MaxBottomtime]

I hadn't noticed any difference, although I made deep stops for many years. My average ascent rate is 17 feet per minute, so I've never felt tired after any dive.

 

[lowwall]

Are you diving square profiles? Deep stops are pointless if you are already spending a lot of time shallow. For example if you slowly follow the bottom up on a shore dive or hang around at the top of reefs in the 30-40' range on a boat dive.

Also, which computer are you talking about? Each manufacturer does their deep stop a little differently.

Just a quick note, the thing that's been largely discredited is deep stops on deco dives. The research on single, mid-depth safety stops - which is confusingly also called a "deep stop" - is limited and somewhat contradictory, but it hasn't been debunked the way that starting deco stops at much greater depths has.

 

[SlugLife]

(Rec-Diving response)

I've changed my diving habits overall, and noticed I usually am less tired after dives these days.

• I try to avoid any exertion underwater. If my breathing-rate goes up to a moderate (or higher) level, I slow or stop my activity. I try to remember to use large, gradual, slow, consistent kicks. This also greatly extends dives/air.
• I avoid changes in elevation in general, both up and down. I may try to stay within a certain range, such as 30-to-45 feet, where I can go up or down within that range, but usually not outside that.
• I deliberately ascend slower, especially when 20ft or less. I can even do a bunch of "bounce dives" (surfacing several times) by being super-gradual near the surface.
• As air decreases, and assuming near a shore, I typically decrease my dive-depth range. For example, if at 90-120ft, I'll lower it to 30 to 60ft, then 15 to 30ft. This also helps with air-management, potential emergencies, and extends the dive a little.

While not a "change" I also know that drinking plenty of water and ensuring proper thermal-protecting can help significantly as well.

For rec-diving, I don't do any "deep stops" but I just gradually surface towards the end of the dive.

---

I'm not a technical-diver, but I'd say the advantage of having specific stops for tech-diving is it's easier to follow a routine or check-list, and there are much greater risks, if you don't plan or deco properly. You could probably do something like make the "staircase" profile a little less harsh, by adding more stops, but shorter time at each stop.

Keeping things simple may be important if you're narc'd or otherwise not at 100%.

 

[boulderjohn]

Deep stops for decompression dives are definitely out of favor right now, although in reality those who are supposedly against deep stops are still stopping deeper than the pure algorithm calls for.

As for NDL diving, the research is not as clear. A couple of studies about 20 years ago suggested deep stops on NDL dives were good, but those studies are not highly regarded these days. My study of that research (what little there is) suggests to me that we just don't know enough to make any conclusive statements.

Think about the following three dives:

1. Diver goes to 90 feet for 3 minutes less than NDL, does a safety stop, and goes to the surface.
2. Diver goes to 90 feet for 3 minutes less than NDL, stops at 45 feet for 2 minutes, does a standard safety stop, and goes to the surface.
3. Diver goes to 90 feet for 3 minutes less than NDL, ascends to 60 feet and stays there for 15 more minutes, ascends to 30 feet and stays there for 15 more minutes, does a standard safety stop, and goes to the surface.

There is no definitive research indicating that any one of those profiles is safer than the others.

If I had a computer with a deep stop feature, I wouldn't bother with it.

 

[Alaskan Scuba Dude]

Fatigue after a dive could have numerous implications. Perhaps you weren’t using Nitrox. Perhaps you weren’t hydrated the night before? Perhaps your fitness level is wanting? If you have accidentally exceeded the No Decompression Limit while at 100 ft, you may want to consider deco ratio on the fly (risk mitigated) by ascending to 40 ft and remain there for 3-minutes, then ascend to 30 ft and remain there for 3-minutes, then complete your Safety Stop for 3-minutes at 16 ft. Discontinue diving for 3-hours minimum.

 

[Blackcrusader]

Fatigue after a dive could have numerous implications. Perhaps you weren’t using Nitrox. Perhaps you weren’t hydrated the night before? Perhaps your fitness level is wanting? If you have accidentally exceeded the No Decompression Limit while at 100 ft, you may want to consider deco ratio on the fly (risk mitigated) by ascending to 40 ft and remain there for 3-minutes, then ascend to 30 ft and remain there for 3-minutes, then complete your Safety Stop for 3-minutes at 16 ft. Discontinue diving for 3-hours minimum.

I have done vacations where I do 40 dives on air in 2 weeks, also done 40 dives on nitrox for 2 weeks. I feel no different using nitrox. Many claim it makes them less tired but I don't find any difference.

 

[Wathdoc]

In my view, apart from tec dives, what you do in the last six meters is what makes the difference, I extend time at 6m, come slow to 3m and spend a minute there and take time coming up. The pressure difference in the last 6m is considerable.

 

[doctormike]

Deep stops for decompression dives are definitely out of favor right now, although in reality those who are supposedly against deep stops are still stopping deeper than the pure algorithm calls for.

As for NDL diving, the research is not as clear. A couple of studies about 20 years ago suggested deep stops on NDL dives were good, but those studies are not highly regarded these days. My study of that research (what little there is) suggests to me that we just don't know enough to make any conclusive statements.

Think about the following three dives:

1. Diver goes to 90 feet for 3 minutes less than NDL, does a safety stop, and goes to the surface.
2. Diver goes to 90 feet for 3 minutes less than NDL, stops at 45 feet for 2 minutes, does a standard safety stop, and goes to the surface.
3. Diver goes to 90 feet for 3 minutes less than NDL, ascends to 60 feet and stays there for 15 more minutes, ascends to 30 feet and stays there for 15 more minutes, does a standard safety stop, and goes to the surface.

There is no definitive research indicating that any one of those profiles is safer than the others.

If I had a computer with a deep stop feature, I wouldn't bother with it.

Very helpful summary post. And yes, as mentioned upthread, the term "deep stop" is ambiguous in this context.

From a methodologial point of view, it's hard to do such a study, since you don't have an easily quantifiable outcome metric. If you are looking at the rate of clinical DCS requiring recompression, you may be able to pick up meaningful differences between the control group and the experimental group. Even if you are doing doppler bubble measurements (which don't strictly correlate with clinical DCS), at least you have something you can measure.

But trying to measure minor differences in "tiredness" on recreational, no-stop dives is not an easy thing to do, since there are so many variables contributing to that reported sensation, and different people may score differently, etc.. The way to improve your statistics in a situation like that is to bump up your N (i.e. do a massive study with a large number of individuals), which would hopefully minimize the effect of individual variablity not associated with the test variable (deep stops). But of course, that's expensive and not very practical.