Deep Stops

I've met a few divers now that have suffered repeated "mild" skin bends. Some of which have been treated with hyperbaric recompression and some by simply admionistering 100% O2 on demand until all apparent symptoms have disappeared. Naturally they all continue to dive, but now advocate deep stops, sometimes including Nitrox.

Does the BSAC or anyone else for that matter have any information to support the theory of deep stops after deep dives. As to me, it makes perfect sense to carry out stops starting at half the depth between the deepest depth and the first recommended stop. This would allow micro bubbles to dissipate before their growth is accelerated by the increased pressure gradient on rising directly from depth to the first recommended stop.

Any info would be greatly appreciated

Thanks

Geoff

I've met a few divers now that have suffered repeated "mild" skin bends. Some of which have been treated with hyperbaric recompression and some by simply admionistering 100% O2 on demand until all apparent symptoms have disappeared. Naturally they all continue to dive, but now advocate deep stops, sometimes including Nitrox.

Does the BSAC or anyone else for that matter have any information to support the theory of deep stops after deep dives. As to me, it makes perfect sense to carry out stops starting at half the depth between the deepest depth and the first recommended stop. This would allow micro bubbles to dissipate before their growth is accelerated by the increased pressure gradient on rising directly from depth to the first recommended stop.

Any info would be greatly appreciated

Thanks

Geoff

have a look at
<a href="http://www.bishopmuseum.org/research/treks/palautz97/deepstops.html" >http://www.bishopmuseum.org/research/treks/palautz97/deepstops.html</a>. The original pyle stops !!! also a few reference at the end of the article. I do deep stops when trimix diving, the last 60 meter dive I did the first stop was 38m and then 27 meters for 2 mins. Hope the article helps.

Stu

Hi Geoff

1. BSAC ERD "sort of" teaches deep stops, i.e. you're taught to use (eg) ProPlanner (or similar). If you set the MicroBub option you automatically get deep stops.
2. TDI Trimix actively teaches deep stops
3. Since doing ERD, my buddy and I carry out deep stops - even on (longish) dives in the 30-40m range. We both believe we feel better after the dive(s) by doing so
4. Have a look at the GAP website ( <a href="http://www.gap-software.com/" >http://www.gap-software.com/</a>) you can download a number of papers from there dealing with theory of deco, deep stops, etc.

Thanks Stu & Nick, something to be having a good look at methinks!

Regards

Geoff

Geoff

These were covered a while ago on YD, Peter K and a few others came out with some very good stuff / links and sold me. I tend to use the 2/3 method now (as recomended by Peters Hyperbaric Doc)and that with the very slow assents my branch has always used seems to work well. My SUUNTO eather likes them or is totally confused.

Regards

Paul

Thanks Paul, I remember now, there was something on the YD site a little while ago. I'll go back and have a trawl. Thanks

Geoff

1. What's YD?
2. 2/3 method - where can you get info on this
3. Slow ascents? What do you class as "slow", BSAC ERD and TDI Trimix is based on achieving & maintaining 10m/min

3. Slow ascents? What do you class as "slow", BSAC ERD and TDI Trimix is based on achieving & maintaining 10m/min

Um, Only at depth. what you want to achieve is a exponential ascent rate. Part of this is by adding stops, partly by slowing your ascents as you get shallower. (i.e 6mins from 6m to the surface)

Have a play with some software like GAP that gives you a graphical represenation of the dive. Set the Gradient factors to 20/80 and see what the output gives you.

HTH
John

Um, Only at depth. what you want to achieve is a exponential ascent rate. Part of this is by adding stops, partly by slowing your ascents as you get shallower. (i.e 6mins from 6m to the surface)

Agreed - was referring to stops prior to 6m. In fact when I did ERD, an extra safety stop was invariably introduced at 3m followed (where conditions permitted) a 2min ascent from 3m!!

Have a play with some software like GAP that gives you a graphical represenation of the dive. Set the Gradient factors to 20/80 and see what the output gives you.

Have GAP, prefer it to ProPlanner for the simplicity of production of BailOut reports etc.
One problem I've found with GAP, is it that I'm not sure it calculates EAD/END correctly???

:=Um, Only at depth. what you want to achieve is a exponential ascent rate. Part of this is by adding stops, partly by slowing your ascents as you get shallower. (i.e 6mins from 6m to the surface)
Agreed - was referring to stops prior to 6m. In fact when I did ERD, an extra safety stop was invariably introduced at 3m followed (where conditions permitted) a 2min ascent from 3m!!

:=Have a play with some software like GAP that gives you a graphical represenation of the dive. Set the Gradient factors to 20/80 and see what the output gives you.
Have GAP, prefer it to ProPlanner for the simplicity of production of BailOut reports etc.
One problem I've found with GAP, is it that I'm not sure it calculates EAD/END correctly???

Well you could always calculate it yourself. I don't know if GAP will do END with O2 as Narcotic, which might be where you get differences.

Can't actually comment on GAP much as I use Decoplanner

I also don't care too much about ENDs as I tend to use standard mixes, which have ENDs of less than 30m at the depths you use them.

Also, EAD and END are different things, EAD is used for calculating Decompression using Air tables, while diving Nitrox, END is used as a measure of Narcosis in Trimix.

John