Safety stop question

Bibendum · Jun 21, 2005

Ok, so I have what is probably a stupid question, but I'm gonna ask anyway.

If you are shore diving, and you go past 30 feet, you still do a safety stop at 15 feet right? Someone was telling me that the safety stop is only used when boat diving and this doesn't seem right to me.

If the purpose of the stop is to aid in off-gassing while ascending from +30 feet (and to aid in a slow ascent), it shouldn't matter if you went from the surface (ie -boat diving) directly to +30 feet vs. following the bottom from shore to +30 feet...you'd still do the 3 minute safety on the way back up to the surface, or to the shore, right?

Thanks!

jonnythan · Jun 21, 2005

The person who told you that you don't do it when shore diving probably meant that on a lot of shore dives, your ascent is along the shoreline and so it's very slow and you spend a lot of time shallow. In any case, you should still do your safety stop.. just be aware that you might do a "safety stop" by swimming around at 15-20 feet when coming back into shore.

String · Jun 21, 2005

Worth noting a safety stop is NOT a mandatory stop. Its an optional stop for potentially increased safety. If you've planned the dive properly and executed it properly not doing one at all wont hurt you.

Diver0001 · Jun 21, 2005

Bibendum:
Ok, so I have what is probably a stupid question, but I'm gonna ask anyway.

If you are shore diving, and you go past 30 feet, you still do a safety stop at 15 feet right? Someone was telling me that the safety stop is only used when boat diving and this doesn't seem right to me.

If the purpose of the stop is to aid in off-gassing while ascending from +30 feet (and to aid in a slow ascent), it shouldn't matter if you went from the surface (ie -boat diving) directly to +30 feet vs. following the bottom from shore to +30 feet...you'd still do the 3 minute safety on the way back up to the surface, or to the shore, right?

Thanks!

PADI has clear rules about this when you use their RDP for planning. You need to make a safety stop whenever you go deeper than 100 ft or when your dive ends withing 3 letter-groups of the NDL.

My thinking about this is that you should add a safety stop to every dive deeper than 5 metres unless there is a really pressing reason not to.

R..

Bibendum · Jun 21, 2005

Thanks all. I knew the safety stop isn't mandatory, only recommended, but it just didn't make sense to me that you wouldn't do one simply because you were diving from the shore. When I went back and checked my book, it stated a safety stop is recommended for all dives beyond 30 feet.

Thanks for confiming the info. and solving my confusion!

pt40fathoms · Jun 21, 2005

As has been mentioned previously, often when diving from shore, your safety stop is done while heading to shore. Provided the slope upwards to shore is shallow and long enough to take about 3 minutes to go from 18 feet to 13 feet. If not, then a pause at 15 feet till your 3 minutes is up is all that is often required. Always remember to go slow from 33 feet (10 meters) to the surface. It should take one full minute or longer to travel that distance, add the 3 minutes at 15 feet, and the trip should last a minimum of 4 full minutes. If you ascend faster, you will most likely feel fatigued at the end of the dive, even though you made the safety stop. This fatigue is said to be a sign of very mild DCS, you can deal with it and dive again the same day, but why should you if all it takes is slowing down for the last bit of your dive.

Iruka · Jun 22, 2005

I think some people believe a safety stop means "hang on the anchor line at the end of the dive." Because in some cases we might have just done 20 minutes or more, coming back along the top of the reef, at safety stop depths. Maybe they're just unaware of their depths when they're swimming. What's really funny is when about 20 divers are ALL doing their safety stops on the same line...so you have people ranging in depth from about 10' down to 40 or 50'! (and these weren't "intended" deep stops...just no room on the line at the proper depth, so hang on the line wherever you can.)

Anyhow, as a few people have said, typically beach diving includes a gradual, slow ascent along the slope, and the safety stop will normally be taken care of during the swim itself....unless you're one of those Nazis who insist a safety stop MUST be at 15', and not 14, not 16, etc. ha ha.

miketsp · Jun 22, 2005

Diver0001:
..snip..
My thinking about this is that you should add a safety stop to every dive deeper than 5 metres unless there is a really pressing reason not to.

R..

I never heard anybody establish a limit as low as 5m for a safety stop to be added.

Most operators I have dove with use 15m as the breakpoint.

Haldane's experiments demonstrated that bubbles only form after a 2:1 pressure drop which would be 10m and even though I have seen opinions expressed on this board that some modern theories state that small bubbles / micronuclei are always present, and that reductions in pressure will cause them to expand, I have not so far located any experimental evidence of problems caused by drops below 2:1.

Diver0001 · Jun 22, 2005

miketsp:
I never heard anybody establish a limit as low as 5m for a safety stop to be added.

Most operators I have dove with use 15m as the breakpoint.

Haldane's experiments demonstrated that bubbles only form after a 2:1 pressure drop which would be 10m and even though I have seen opinions expressed on this board that some modern theories state that small bubbles / micronuclei are always present, and that reductions in pressure will cause them to expand, I have not so far located any experimental evidence of problems caused by drops below 2:1.

Most people these days recognise that 2:1 was a little too much. If I"m not mistaken the going thinking is 1.6 :1. That would make 6 metres.

Either way, 6 metres or 10 metres I don't see the harm in doing a safetystop at the end of most dives. It's not even really an issue of decompression in my mind as much as a matter of good habits.

YYMV

R..

Tom Yerian · Jun 25, 2005

Correct, within reasonable depth, time and ascent speeds.
Capt. Tom

Safety stop question

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