PEOPLE - Don't Lie about your dive experience!!

[Gombessa]

Ha... but the time I got those signals flashed, the safety stop would be over!

It's usually pretty fast - 3 seconds or so total to flash the signal. For example, from 20 feet:

"level off; deco 1 min; ok." Hang for 30 seconds.
"Ascend to next stop; ok." Move up 10 feet over next 30 seconds.
"level off; deco 1 min; ok." Hang for 30 seconds.
"Thumbs up." Ascend to surface over next 30 seconds.

With someone unfamiliar with the signal, we do it slower and more deliberately.

 

[river_sand_bar]

Hand signals for a person needing air... buddy is OOA.

2 fingers up then 3 fingers down followed by 2 fingers crossed down....

Want my air??? Visa (2 fingers up), Mastercard (3 fingers down) or American Express (2 fingers crossed down)....

 

[caseybird]

Lets see ... 3 minute stop at 15 fsw.

Fist: Stop.
Point to gauge: Depth
Flash 15: 5 fingers three times (or just 4 fingers if I'm with a buddy who is into binary "01111," yes ... we do that)
Point to watch: Time
Flash 3: 3 fingers (or just thumb and index finger if I'm with a buddy who is into
binary "00011," yes ... we do that).
Level off: Flat hand palm down moving away from body.
OK?

If I start giving hand signals in binary, please get me to the surface and put me on
O2. I'm obviously narced.

 

[neil]

As far as safety stops are concerned ... as one of those who was in on originating them, let me tell you truth. The idea of safety stops came out of some research that showed that recreational divers were, in point of fact, making their ascents between 100 and 120 feet per minute, back when a standard ascent was 60 fpm. I think it was at the AAUS Decompression Computer Workshop that Bruce Bassett suggested perhaps a stop between 20 and 10 feet for two to three minutes would be as effective as actually getting divers to slow down to 60 fpm. In addition it would cover most errors of one depth too deep or one time too long.

Then along came dive computers with ascent meters and such and the reason for the stop was forgotten, just the procedure was remembered.

Thal,
It was my understanding, from having read the Proceedings of the Biomechanics of Safe Ascents Workshop, that the original study and naming of safety stops was done by Andy Pilmanis, in a paper published in 1975 which predates the computer workshop by more than a decade. Bassett made the recommendation, but I don't think he originated it.
Neil

 

[Thalassamania]

I do believe that you are correct. I also know that Andy gets far too little credit for his many contributions to diving.

 

[Jim Ernst]

Quite frankly I have no idea what the "sign" for a 3 min 15 ft stop would be. I'd probably understand yours, and I'd have little trouble making a sequence that would convey the idea ... but lots of foreigners are used to saying "yes, yes, yes" even when they've not the vaguest idea of what you're saying.

As far as safety stops are concerned ... as one of those who was in on originating them, let me tell you truth. The idea of safety stops came out of some research that showed that recreational divers were, in point of fact, making their ascents between 100 and 120 feet per minute, back when a standard ascent was 60 fpm. I think it was at the AAUS Decompression Computer Workshop that Bruce Bassett suggested perhaps a stop between 20 and 10 feet for two to three minutes would be as effective as actually getting divers to slow down to 60 fpm. In addition it would cover most errors of one depth too deep or one time too long.

Then along came dive computers with ascent meters and such and the reason for the stop was forgotten, just the procedure was remembered.

Do I do "safety" stops? Sometimes, but far from always. I try to be fairly rigid about my ascent procedures, safety stops are for when something has made me sloppy and I want to be extra careful.

Thanks to you for a great post, Some of what just taught me some more good knowledge!!