Safety stops - depth, duration and trim

[BuoyantC]

The worst thing about safety stops is as a previous poster alluded to, and that's when divers "bolt" the last 15ft. to the surface. Sort of negates anything they may have accomplished with the stop.

As for the horizontal/vertical thing, I'd venture to say most divers can't hold their depth within a couple feet through a three minute stop. It can be even worse if they're hanging on an anchor line in surge. Staying put has to far outweigh position.

And deep stops...Why not? Being older and of less than an ideal figure, I'll take any safety advantage I can get. Remember decompression theory is just that, theory.

 

[Blackwood]

The point that has yet to be made is that with a 30 foot ascent rate (if you actually stick to it) safety stops are a waste of time. Safety stops were initiated back in the days of a 60 FPM ascent rate that was honored more in the breach than in the practice.

I no longer consider anything I do to be a 'safety stop.' I have a specific ascent protocol to which I adhere, and it involves a specific patterns of stops.

All my commentary about body position during a stop can be applied equally to decompression stops and safety stops (superfluous or not*).



*Are most new divers who don't use computers with alarms really ascending at 30FPM (or within the assumed maximum rate of the common models)?

 

[Thalassamania]

...
*Are most new divers who don't use computers with alarms really ascending at 30FPM (or within the assumed maximum rate of the common models)?

Frankly, the major thing that I like about computers is that they seem to have slowed down ascents. 5 feet/10 seconds should not be that hard either, but your watch and depth gauge don't actively complain when you exceed it.

 

[captain]

Thal, any thoughts on this bit of accent rate history from the NEDU

http://www.scubaboard.com/forums/nedu-q/268621-us-navy-tables-ascent-rate.html

 

[Thalassamania]

Thal, any thoughts on this bit of accent rate history from the NEDU

http://www.scubaboard.com/forums/nedu-q/268621-us-navy-tables-ascent-rate.html

I've commented on that repeatedly, going back as far as 2006, the stories are all basically the same, a few details have been changed, forgotten or invented, and those of us who are brave (or stupid)enough to tell sea stories that belong to others have to the best we can to winnow the wheat from the chaff without doing violence to the essential facts or loosing the basic human interest of the tale.

 

[String]

Problem ive seen lately is so many divers train on and completely rely on computer ascent rate gauges that when their computer fails and they're diving without that have absolutely NO idea how to control an ascent and keep the speed safe without that little graph to tell them.

 

[rstofer]

Which brings up the point: if a direct ascent at 60 fpm with no safety stop is safe how can it possibly matter which orientation you use if you do make a stop? Why overanalyze it? It's a safety stop, not a required decompression stop. It seems like we're using a micrometer to measure the hole we plan to dig with a backhoe.

The PADI tables are still set for 60 fpm although NAUI backed off to 30 fpm in 1989. Probably because, as Thalassamania said, divers were actually doing 100+ fpm. I know I overran the 60 fpm many times and I NEVER made a safety stop. The NAUI tables are very specific about the NDL and what kind of deco stop to make if you overrun it. The 1987 version allowed 60 fpm ascent.

Of course, there are those that point out that the results of my transgressions are still noticeable.

I remember when we used to have a horizontal pipe about 10' below the water for boat divers to hang onto if they wanted to do a safety stop. There was often a spare tank and regulator. Sometimes it was just a rope with a tank and regulator.

Richard

 

[fnfalman]

Which brings up the point: if a direct ascent at 60 fpm with no safety stop is safe how can it possibly matter which orientation you use if you do make a stop? Why overanalyze it? It's a safety stop, not a required decompression stop. It seems like we're using a micrometer to measure the hole we plan to dig with a backhoe.

Yep. Just do the damn safety stop, horizontal or vertical, and surface slowly. Don't overcomplicate things that don't need to be complicated.

 

[dumpsterDiver]

I'm not one to worry too much about horizontal trim during the dive, but if divers can learn to do their ascent in the horizontal position, the extra drag will allow them to better control their ascent. It works on the hang and it works on the ascent as well.

I generally use large freedive fins, and can produce a lot of drag in the vertical position as well. Just hold one fin straight out in front (more or less) and the other leg bent 90 degrees to allow the back of that fin to catch water works very well too. Vertical is also a safer way to make the final ascent because you can look up for obstructions more easily than when laying face down in the water.

Maintaining a vertical position in the water during ascent provides a significant advantage in some situations, because it allows you to scan for sharks and you can more easily spin around and look behind you when solo. Being vertical and face to face allows buddies to look over eachothers back for sharks.

 

[diver 85]

What's your average dive profile(BT, EAN or air) for dives below 75'? Deep stops aren't really something that's used unless you're going deep(i.e. way outside of "recreational" limits, usually with a helium mixture).

It's not going to be detrimental since you're going to start off-gassing between 60-70 ft for most profiles at 100 ft, but.....a shallower, longer stop and/or very slow ascent from your safety stop to the surface would be much more beneficial.....at least that's the current theory.

Back in the days, way back I'm talking, some were taught to bolt as fast as possible for their first deco stop from the bottom. Makes sense given the knowledge back then......the 60ft/min ascent rate was standard because that's the max rate a navy diver in a suit could be mechanically "reeled" up, so to say, and it just carried over.....today the theory is obviously different.

air and talking about when pushing or busted the NDL....and........the older I get, the more stops I'm making, just makes sense...plus if I come back with 200 or 500# of air, it doesn't matter, no one has ever given me credit on air I bring back to the boat..also. I was taught 60fpm but finally went to 30 (again in my older days).....hate when my dang computer goes beep beep beep, it's annoying, right??

dang it's bad to get old-----but sure beats that other thing(y).....