Deep stops and ascents...

[wilkie]

I have been doing a slow assent, >30'/min, to 30' or so, for about 3 min,
slow assent,> 15-20'/min to 15', for 5min, then 3 to 5 min to surface, or just "bottom scratch" if terain permits. Not taught in any class that I have atended, just my own SWAG, from what I've read, and tring to make since of various tables.

Have only reciently heard of "1/2 depth" stops, and "minimum deco", and intend to learn more about these precedures.

 

[cmalinowski]

usually i just swim upslope and spend time shallow. on square profiles, though, its 1 minute stops from 1/2 max depth, and often it looks more like 1-1-1-2-3.

I'm along these lines too.
Chris

 

[lowwall]

I used Uncle Pug's checkmark profile on my last dive trip (to Grand Turk). The lack of fatigue compared to my previous dives with just a 3 minute safety stop was very obvious.

Next time I dive where there is nothing to see on the way up, I'll do 2-3min at half, 2-3min at the next half (if it's greater than 20') and 3-5min at 15' then a slooow ascent to the surface.

I actually began wondering if the 3min safety stop was the whole story after my last dive in Little Cayman last year. Instead of just heading up to the boat with the DM, my wife stuck to the bottom and began slowly following it up to the boat, which was moored in about 10' of water. I figured out that she wanted to show off her improving air consumption (she had started the trip with just 10 dives) and be the last one back up. The computer seemed to be happy, so we lolled around in the shallows, eventually ascending with 74 minutes. Since we'd been falling asleep as soon as we got back to our room all week, I was sure we were going to be completely exhausted after that time underwater. To the surprise of both of us, we were fine, didn't even need a nap.

 

[Texass]

A couple of links from DAN on the subject. Just a note - the 2nd one is a PDF that doesn't seem to open until I go to page 2 then back to page 1. That may just be my computer.

http://www.diversalertnetwork.org/news/article.asp?newsid=514

http://www.diversalertnetwork.org/news/download/marronifinal1888acapcoraut.pdf

 

[Trinigordo]

How many recreational divers practice this? Was this covered in your Open Water class at all?

I always do a safety stop as it is something relatively easy and logically seems like it would be very beneficial, the "deep stop" principle also sounds very logical and I will probably start implementing it now that I think of it. I do not recall any reference to a "deep stop" in either my OW or AOW certs and don't recall every coming across the idea before.

 

[diverdan214]

We covered a deep stop in my deep diving class, not a standard part of the course, something my instructor added.

 

[rsdancey]

For dives deeper than 100fsw, I do a deep stop of 1 minute at bottom - 2 ATA. Were I to do dives deeper than rec limits, I'd probably end up with multiple stops; every 2 ATA from the bottom up the start of our "simulated deco".

We do "simulated deco" (I refer to it as simulated because it's not required by the tables, and we could make a direct ascent to the surface if necessary) of 1 minute stops in 5 foot increments from 30 feet to the surface.

Rationale:

Decompressing the body by 2 ATA or more even at a rate as slow as 30ft/minute can trigger a cascade of bubble formation. The deep stop tends to help avoid this problem. For dives less than 100fsw, the start of our "simulated deco" occurs at or above the 2 ATA limit, so we don't do an extra stop on those dives.

The series of 1 minute / 5 foot stops at the top of the dive provides a large margin for error and virtually assures that we get enough stopped time under high enough pressure to clean up most of the bubbles before we exit. It's also excellent practice for technical diving.

Ryan

 

[PfcAJ]

For dives 60-100ft, stops begin at 50ft. Hang for 30, travel for 30 in 10 ft increments. For dives flirting with the NDL, an extra minute at 20 and 10 is sometimes added.

0-60ft, stops begin at 30ft and proceed as stated above.

Never faster than 30ft/min, always horizontal.

Most of my diving is in caves, so the pause at 75% is usually included in the way out as a result of cave countour.

Your post dive fatigue is a good way to measure the effectiveness of your deco. I can easily tell when I did an innappropriate deco, hence the extention of the 10ft and 20ft stops, depending on the dive profile.

Be aware that very slow acents can lead to additional ongassing. Be safe, but don't spend an extraoridinary amount of time coming up.

 

[vkalia]

Deep stops are certainly very fashionable these days - without any regard to whether or not they serve any purpose or not.

I do them religiously on dives where I am deeper than 50m, or on mix - so I am actually a big fan of deep stops. I have walked away from a potentially very serious hit b/c of them. BUT....

For typical recreational profiles, it doesnt make a snit of a difference whether you do deep stops or not - no matter how fashionable they may be. I find it a bit funny when I see loads of earnest - and well-meaning divers - doing a deep stop after a 24m doddle along the reef or whatever.

IMO, deep stops in a recreational context make sense when there is a valid risk of the free gas phase posing problems: 3 or more dives (especially 2 or more deep dives) in a day, reverse profiles, yo-yo dives or such. Otherwise, a normal slow ascent followed by a safety stop works well enough.

Heck, normal safety stops are what millions of divers still do without any problems, so in a significant majority of rec dives, it is a solution in need of a problem.

I am not saying deep stops are a bad idea, incidentally. Doesnt hurt to have a wee bit more safety. I do teach deep stops, but in AOW - not in OW. For 20m dives, it is not needed. For deep dives, it doesnt hurt to do it... and in some cases, it is indeed helpful.

My only gripe with it is that a lot of people latch onto it without truly understanding how or why it is useful, and somehow think they are safer divers. Following any rule blindly is not the way to become a good diver, IMO.

Vandit

 

[jbisjim]

Pyle Stops