Deep stops and ascents...

[Charlie99]

Were I to do a 1 minute stop at half depth, it would not be half of the deepest point on the dive, but rather 1 minute at half of the deepest I had been during the last 10 minutes or so.

I generally do about 1 minute at 40, 2 minute at 25-30', and 3 minutes in a slow glide from 20' to 8'. If heavily loaded, the times get longer. If the ascent starts from deeper than 80' or so, then the stops are more like 1@50, 2@35, and then 25-15' glide over 3 minutes.

I don't worry as much about the instantaneous ascent rate as much as what the average over a minute or so looks like. When I start my ascent, based upon how heavily loaded I am, I pick a runtime at which I want to get out of the water. Then I figure out when my ascent to 40' + 40' stop should end. I can generally keep those 2 numbers in my head long enough to do the stops.

 

[millphils]

OW covered only 3 min stop at 15 ft. A shop DM turned me onto making a 1 min stop at 1/2 depth. I incorporate this along with 1 min at 15 ft, 1 min at 10 ft and 1 min at 5 ft.

 

[Charlie99]

My buddies and I do the pause at 75% max depth, pause at every 10ft until 50% then, 1 minute stops every 10ft thing. This practice is taught to all the recreational divers by the crew I get my instruction from.


I think you are gonna find all the so called "DIR" dives practice this. .

I think that you will find that not all DIR divers agree that this more or less linear 10fpm ascent all the way to the surface is the ideal shape of ascent curve. The ideal "shape of deco" is slower as you get shallower.

Here's one of several threads that discuss this: http://www.scubaboard.com/showthread.php?t=77895

Another DIR diver, Peter Steinhoff of Sweden, has at www.dir-diver.com some minimum deco tables with mandatory stops of 1 @ 40', 1@30', 3@20', 3@10' . Note that the ascent gets slower when shallower.

 

[TSandM]

Then I figure out when my ascent to 40' + 40' stop should end. I can generally keep those 2 numbers in my head long enough to do the stops.

This was an approach I got out of something Diver0001 wrote a while back . . . That stops were really a way of slowing ascent speed. Ascend to the next stop point, and if you haven't used all the required time to get there, stay there until you have. But Marroni's study suggests there may actually be an advantage to moving up and stopping, as opposed to a very slow ascent rate. At least, if I remember the paper on the DAN site correctly, the 30 fpm ascent with stops was better for bubbles than the 10 fpm ascent, at least for the profile they were diving.

 

[LiteHedded]

I'm bad
I just do my safety stop

 

[Charlie99]

This was an approach I got out of something Diver0001 wrote a while back . . . That stops were really a way of slowing ascent speed. Ascend to the next stop point, and if you haven't used all the required time to get there, stay there until you have. But Marroni's study suggests there may actually be an advantage to moving up and stopping, as opposed to a very slow ascent rate. At least, if I remember the paper on the DAN site correctly, the 30 fpm ascent with stops was better for bubbles than the 10 fpm ascent, at least for the profile they were diving.

My reading of the paper is that it wasn't the "move & stop" vs "slow move" that made the 10fpm ascent worse. The problem was that the 10fpm and 3fpm constant linear ascents spent longer while deep enough that it was adding more loading to the 10-20 minute compartments, and then didn't hang around shallow long enough to offgass them.

If you go to any deco program and crank up the conservatism, you will generate a series of stops that get longer as you get shallower.

So rather than saying that there was an advantage to moving and stopping vs continuous ascent, I understood the paper to just be saying that your body kind of averages things out over the period of a minute or two, and what counts is the depth change over a minute or so, rather than the instantaneous rate as measured over a few seconds.

 

[divermike1989]

When I'm deeper then 80-90 feet I'll do a stop at 1/2 my depth for a minute or two then the normal safety stop that you learn in class.

 

[divingjd]

Always five minutes at 15-20, three minutes at half the depth on dives deeper than 80 feet. On a reef, this usually translates into a multi-leve dive, on a Great Lakes wreck dive, it's hanging at 50-60 feet. The deep stop was not covered in my OW, although I discuss it with my students now. The safety stop was covered in OW.

 

[BDub]

I teach my OW students to do a 1 minute 1/2 stop, an ascent rate of 10' per minute, and a 3 minute stop between 10-20', followed by a slow ascent from 10' to the surface.

 

[JimC]

30fpm to 1/2 depth
pause to sync up team/watches (usually about 30 seconds)
1 min / 10 foot rolling stops to 20
2-4 minutes @ 20
3-6 minute accent from 20 to 0