The ´Safety Stops´Debate.

[Richard Mason]

Originally Posted by Lynx737

On a deeper no stop dive it is the 5 minute halftime tissue compartment which limits the dive time and as a consequence a 3 min safety stop really helps to off gas the limiting compartment. If you dive for longer at shallower depths other compartments limit the dive and a 3 minute safety stop is of less value.

Doppler tests show 1/5th the level of silent bubbles from divers having completed a 3 minute safety stop. The evidence is plain a 3 minute safety stop is of great value in reducing DCI risk especially after a deeper dive.

That said is is just a safety stop and a no stop dive is exactly that, if there is a need to get out of the water for other safety / gas related issues then get out of the water.

Doing a dive tomorrow, with my son & Keith Whittaker and friend on Isle de Phoques off the East Coast. We are diving there (if the weather's ok) primarily because its a seal colony, max depth will likely be 10 maybe 15M. This is some video taken last February at this spot:



However, while I don't view this as a hazardous dive per se, the thought of floating around for 5 @ 5 in SE Aus waters next to a seal colony doesn't rate as a comfortable experience to me. So guess what, we (my son & I) will be missing out the safety stop.

[Fiona]

Originally Posted by MATTBIN

Hang horizontal too.

Matt

Originally Posted by Mal Bridgeman

Hi Matt,

I have often heard this mentioned....do you think there is a genuine benefit or is it to look cool?

Mal

Originally Posted by Mal Bridgeman

So, if it is just to look cool then I am happy with that.....!...Mal

Oh how people change

[Mark Chase]

Originally Posted by Tony F

I think that increasing the assent time and undertaking a safety stop, so long as gas permits, is always going to add more conservatism. Therefore even having suffered a problem if the stop can be safely undertaken then that would be my preferred course of action always.

Certainly the stop may be 'optional' under many circumstances, but any simple policy promoting safety has to be a winner in my book.

This is slightly wrong.

Increasing the ascent time INCREASES THE RISK unless you compensate by adding stops.


The PADI RDP allowed for an 18m/min ascent rate. If you cut this to say 5m/min then your increasing the onngassing during the deep phase of the dive.

As an example:

The RDP is already a very aggressive deco schedule. 20mins at 30m on air is 100/100GF deco which makes it a NO STOP DIVE which i would never do. I run 10/95 GF deco at the moment which would add a 3m/min ascent from 18m gives me a total of 7mins deco


Adding a slow ascent does not increase safety but it does remove some of the stress on your body.

Adding a shallow safety stop does increase safety.


However the most important rule in diving is survive the dive. So screw safety stops screw conservative deco if the choice is breath water or breath air at 1 ATM then go for the air every time. With the level of diving that has no understanding of decompression it is very likely the DCS if any would be treatable.

Regardless of how much deco I had, id take my chances on the surface rather than breath water.


That said it is vital that people realize 50bar is not OOA. 50bar is a shed load of gas at 6m. Even at a rather excitable 30SAC it gives you 13mins of gas.

Plenty of time for a 5min safety stop.


The red zone should be removed from the SPG of all novice divers it does more psychological harm than it does good IMHO. People have died spitting the reg at depth because the needle was in the red???? Incredible but true.

ATB

Mark

[Paul Evans]

Great Thread Mal. Good to see it back.

When I bailed at Stoney on the unit we had been in the water for 30ish min's mostly at 20m, We had just gone over the side into the pit, probably around 32m when I got a mouthfull of water, I bailed instantly. Make no mistake. I was teriffied. It took about 2 minutes to calm down, my breathing rate was astronimical. Adrian was in front of me before I realised what was happening. we started an accent that was "Eratic" wthout a line and SMB (Big mistake in that situation, This is where I failed my training, not the other way round) I switched the VR3 to OC, at one point the assent alarm flashed up, on average I'd say 12m min accent. Stopped at 6m and started a saftey stop, (At this point Ada took the camera and started snaping away pi@@ing himself laughing )Actually this was the best thing he could have done, it really calmed me down. After a 1 minute stop we sufaced slowly.
I had 32% in the bailout.

Looking back on it I would have been happy to stay there, but I knew I had run up no deco so thought it safe to accend. Also looking back on it I WOULD stay there if it happened again.

In Mals first post of this tread he mention's how diver's become to reliant on computers, Blindness as he puts it, I didnt used to agree with this, but since I started with the RB I have always had a plan. On this particular "Fun dive" it wasn't written down on a slate, but it was in my head. I knew how much time I would have approximately before I would be in deco. As I progress I will always PLAN THE DIVE and have a back up tables, computer's are great, don't get me wrong, but they can't be relied upon.

I think its important to remember ALL diving is Decompression diving and should be treated with the greatest respect. Yes there are times when you will not do a saftey stop, but I think you should do them unless it is unsafe to do so.

As someone as ponited out you can treat DCS, you can't treat drowning, even if the person is got out of the water alive, the chance's of Secondary drowning are very very high.

[Richard Mason]

Originally Posted by Mark Chase

This is slightly wrong.

Increasing the ascent time INCREASES THE RISK unless you compensate by adding stops.


The PADI RDP allowed for an 18m/min ascent rate. If you cut this to say 5m/min then your increasing the onngassing during the deep phase of the dive.

As an example:

The RDP is already a very aggressive deco schedule. 20mins at 30m on air is 100/100GF deco which makes it a NO STOP DIVE which i would never do. I run 10/95 GF deco at the moment which would add a 3m/min ascent from 18m gives me a total of 7mins deco


Adding a slow ascent does not increase safety but it does remove some of the stress on your body.

Adding a shallow safety stop does increase safety.


However the most important rule in diving is survive the dive. So screw safety stops screw conservative deco if the choice is breath water or breath air at 1 ATM then go for the air every time. With the level of diving that has no understanding of decompression it is very likely the DCS if any would be treatable.

Regardless of how much deco I had, id take my chances on the surface rather than breath water.


That said it is vital that people realize 50bar is not OOA. 50bar is a shed load of gas at 6m. Even at a rather excitable 30SAC it gives you 13mins of gas.

Plenty of time for a 5min safety stop.


The red zone should be removed from the SPG of all novice divers it does more psychological harm than it does good IMHO. People have died spitting the reg at depth because the needle was in the red???? Incredible but true.

ATB

Mark

Fact is, 25 years ago, very few people did safety stops, they didn't feature in the old (77 or 73?) BSAC tables, you just did a straight 15m/min asc ent from whatever depth you were at. And very few people got bent - probably proportionally more than now, true enough but I wouldn't rate the risk as exceptionally high. Then again, a lot of divers were doing 30m dives on a 60 cu ft cylinder (I did a few times), so dives approaching the ndl were few and far between too.

[triplefin]

Originally Posted by Richard Mason

However, while I don't view this as a hazardous dive per se, the thought of floating around for 5 @ 5 in SE Aus waters next to a seal colony doesn't rate as a comfortable experience to me. So guess what, we (my son & I) will be missing out the safety stop.

Richard I'm puzzled by this comment. Obvioulsy from looking at the video you are right in amongst the seals (lovely bit of video btw, must be a fantastic dive I'm very envious) so why not do the stop? Ahhhhhh I've just had a thought as I was going to post this.....is it the sharks you are more concerned about?

[The Duck]

Originally Posted by Richard Mason

Fact is, 25 years ago, very few people did safety stops, they didn't feature in the old (77 or 73?) BSAC tables, you just did a straight 15m/min asc ent from whatever depth you were at. And very few people got bent - probably proportionally more than now, true enough but I wouldn't rate the risk as exceptionally high. Then again, a lot of divers were doing 30m dives on a 60 cu ft cylinder (I did a few times), so dives approaching the ndl were few and far between too.[1]

[1] My bold

And there in lies the rub. More and more people are doing longer dives, pushing the NDL. Last year a skipper, can't remember who, commented that he used to take divers out to the M2 and everyone would be back on the boat after 30min. If I dive the M2 now it will be around 50min on the wreck - ok so this is outside the NDL but (I hope) illustrates the point.

Now if someone is pushing the limits of the NDL then I would think that a safety stop - when safe to do so - is a good thing.

As a separate issue - have any long terms studies been done to see if the inclusion of stops has any long term benefits or otherwise?