Guys, watch the ascent rates

[Tienuts]

Today while diving the wreck of the Union Express, (112 fsw) I was doing a 50 ft stop, and being the first up the line, I was observing all the other divers in the water. While during my 1 minute stop at 50 feet, I observed a pair of diver ascend on the line from depth directly to what appeared to be their 15 foot stop as if they were having a race to the surface. While I was debating if I should give a friendly reminder to these guys when on the surface, another group of 3 divers shot past me, ascending from depth to the surface, with no stops whatsoever. Their ascent rate resembled that of a Polaris missle being shot out of a submarine.

Now I'm not sure if these guys were having a contest to see who can get bent first or what, but I see very rapid ascent rates on most recreational divers whenver I'm on the boat.

Just a friendly reminder guys to please watch your ascent rates.

 

[utdivermatt]

I dont understand. Pretty wreck. Water all around. Why would anyone want to go up at all? Much less fast. Oh well... maybe Im just misguided.

 

[Ben_ca]

Like my Buddy Rob always says:

Stupid's supposed to hurt

 

[fisherdvm]

I think they did a study in which over 1/3 of all divers exceeded the 60 fpm max ascent rate.

Perhaps these folks truly believe in the NDL dive tables. Perhaps they have perfect ear, sinuses, teeth, and can not get barotrauma. Perhaps they are diving with nitrox....

Honestly, I don't grust the NDL that much... Somehow, I always managed to get out from the bell curve. I am kinda odd.

 

[dive_lover88]

maybe they pushed the limit on their tanks and it's on bingo already...
who knows maybe they forgot to release air frm their BC and now they pay for it...
who knows really...

 

[daniel f aleman]

Cringe!


I always wonder how divers will explain their act of ascending faster than 60' per minute when I debrief them during SI? This after I state at the DM predive, "I know that you've been taught 60' per minute but please don't excede a 30' per minute ascend rate, and remember to do a three-minute safety stop at 15'... OK?" (Everybody nods, "Yes".) What I get is a, *Shrug* as an answer... And then I tell them, "You, you, and you, are gonna' sit for an extra hour."

 

[waterpirate]

I beleive that all new divers as part of their open water cert, should watch the goings on a recreational cattle boat, above and below the water. Then they should find waldo pointing out the bingo.
Eric

 

[Sam Miller III]

Suggest all of you and all instructors should have in their libaray;
The proceedings of;

Biomechanics of safe ascent workshop
American academy of underwater sciences
September 25 & 27 1989
Woods Hole, Massachusetts
publication #AAUSDSP BSA-01-90
paper bound-220 pages

Read it -study it,
Then you can critize with great authority and knowledge

Cheers from California --where it all began

SDM

 

[Gene_Hobbs]

I think they did a study in which over 1/3 of all divers exceeded the 60 fpm max ascent rate.

ASCENT RATES IN RECREATIONAL SCUBA DIVES RECORDED IN PROJECT DIVE EXPLORATION.
Denoble et. al. 1998
RRR ID: 662
---Note: Abstract only, no paper available. The table did not transfer well.

BACKGROUND: Rapid ascent after diving may be a risk factor for decompression illness (DCI). Animal studies suggest there are fewer venous gas emboli (VGE) for ascents at 30 fpm rather than 60 fpm, and "safety stops" appear to reduce VGE incidence in humans. In 1993, the US Navy changed the rate of ascent (ROA) for air diving from 60 to 30 fpm. Human studies suggest that slow ascent rates are protective against DCI, but animal studies indicate the efect may be complex and depth related. DAN is investigating recreational diving ascent rates as part of Project Dive Exploration, a multi-year program to collect recreational diving data.
METHODS: 16 women (mean age 39 y, sd 13) and 31 men (mean age 36 y, sd 18) volunteered to contribute their depth-time profiles during 15 dive trips, principally on live-aboard dive boats. Maximum depths during 20 sec time intervals were recorded by dive computers. Dive profiles were analyzed for maximum depth, ascent rate in 20 fsw depth intervals, final ascent rate to the surface, and safety stops.
RESULTS: 357 dives were recorded with no reported DCI. The most frequent maximum depth for this group of divers was 60-80 fsw. One-quarter to one-third of this population sample had ascent rates exceeding the recommended 30 fpm. Half the divers practiced a safety stop as defined as more than 3 min at 20 fsw or less. Max Depth # Depth Range ROA fpm #, greater than 120', 26, 100-120, 62, 80-0, 180, 4, 80-100, 58, 60-0, 120, 14, 60-80, 135, 40-0, 60, 58, 40-60, 54, Any 20', 60, 1, 20-40, 18, Interval, 30, 26
CONCLUSIONS: Dive computers with a recording interval of 20 sec can detect ascent rates in excess of 60 fpm but can miss rates of less then 60 fpm for ascents of less than 20 fsw. For accurate ascent rate measurement, a minimum recording interval of 5 sec is recommended. The effects of ascent rate on DCI risk may become apparent as more dives are collected, and some DCI cases occur.

Ascent rate, post-dive exercise, and decompression sickness in the rat.
Pollard et. al. 1995
RRR ID: 2210, PubMed ID: 8574124
---Note: Non-human

 

[Gene_Hobbs]

Thanks Sam, beat me to it.

Biomechanics of safe ascent workshop
American academy of underwater sciences
September 25 & 27 1989
Woods Hole, Massachusetts
publication #AAUSDSP BSA-01-90
paper bound-220 pages

Lang, M.A. and G.H. Egstrom (eds.). 1990. Proceedings of the AAUS Biomechanics of Safe Ascents Workshop. Woods Hole, MA. 220p

And it can be downloaded here: http://www.si.edu/dive/library_ascentrates.htm
---We have requested permission to add the AAUS Workshops to the Rubicon Research Repository. Their BoD is expected to decide this week.