Decompression stop for shallow dives?

[Charlie99]

Here are a couple of examples form the article:

Diver 1
5m for 30 min (4 ascents)
3m for 30 min
8m for 20 min
10m for 28 min

Diver 2
7.6m for 50 min (4 ascents)
7m for 35 min (4 ascents)
1.7m for 210 min (>10 ascents)

There were however dive profiles that were nowhere near as extreme as those listed above. So, the message is avoid multiple ascents and very long exposures, even on shallow dives

Are there any dive instructors out there that are willing to compare these "extreme" profiles with the profiles they dive while teaching?

 

[miketsp]

Those "extreme" profiles don't look anything as extreme as those done by many DMs I know that do wreck dives where they first do a fast descent to locate the wreck & tie on, then come back to go down with a group, then another descent to untie etc...

Anyway there is a recent report from the HSE (UK controlling body covering health & safety at work) which says:

The report "Yo-yo diving and the risk of decompression illness" by Dr Valerie Flook concluded that the pattern of dives undertaken by people who work, for example, on fish farms is actually less likely to cause divers to bend than the recreational diving practice of diving to the 'no-decompression' limit of a dive computer. 'Yo-yo' dives have previously been considered high risk, yet research shows that the incidence of DCI that results from these dives is lower than that of a single, relatively long, no decompression dive.
Taken from
http://www.divernet.com/news/stories/hse070604.shtml

 

[String]

It did the same thing as any Suunto computer.
At the end of the 3 minutes, it just sat there showing "--" on the NDL/safety stop number display.

Suunto is a little quirky. If you have a rapid ascent at depth, then the safety stop becomes mandatory and it will show a ceiling as you cross 20ft, but it will quickly clear. If you violate the "mandatory" safety stop, then it will go more conservative on consecutive dives. It will also go more conservative if you get into deco, or run multiple rapid ascents... defined as violating 33fpm for even a couple of feet.

The safety stop timer that it runs as you cross 20ft on a 30ft dive is not a big deal, and certainly no reason to toss it... though it could be a reason to switch it to gauge mode and learn to plan the dive and dive the plan.

Seems odd. Thats certainly not behaviour ive ever seen from my vyper. Every dive i get the "STOP" and 3 min countdown for the optional safety stop when i get above 6m.

Despite having a few dives with the "slow" diamonds on the profile somewhere not one of these has ever triggered a mandatory stop with ceiling display. Granted i havent done any >12m/min rate ascents with that rate constant from bottom to reaching stop but i have definately violated its 12m/min for a few seconds on a fair few dives for various reasons.

From checking it seems:

(i) just STOP highlighted with no ceiling == Optional stop of 3 minutes. Not penalised if skipped.

(ii) STOP lit AND a ceiling in top right == Mandatory stop for constant ascent rate violation over extended period. Penalty if missed

(iii) ASC TIME and Ceiling == Mandatory decompression dive. Computer enters error mode if skipped.

Not seen a situation where a mandatory stop is generated yet but if its a constant rapid ascent from depth im not 100% convinced i want to either!

 

[d33ps1x]

What they said. Why do you need your inflator to ascend?

Different strokes for different folks boogie.

Many agencies teach a head above legs or somewhat vertical ascent posture. Many divers who have successfully completed these agencies' courses use this method.

This would entail using the dump lever on the inflator to dump air from the BC.

 

[String]

Most BCs ive seen have a proper dump valve on the opposite shoulder to the inflator hose meaning the corrogated hose isnt needed.

 

[miketsp]

Most BCs ive seen have a proper dump valve on the opposite shoulder to the inflator hose meaning the corrogated hose isnt needed.

Aren't shoulder dumps on the hated DIR blacklist??? :11:
or should that read DIR blacklist of hated devices to be more precise.

 

[ShakaZulu]

Every dive is a decompression dive, there is no such thing as a no-decrompession dive. A "no-stop" dive still assumes that you are ascending at the required rate (30ft/min), thus doing a rolling decompression dive.

My Suunto Mosquito also requires a safety stop if I exceeded 30ft or so, can't remember the exact depth. Why mess with DCS, just do the stop.

 

[d33ps1x]

Aren't shoulder dumps on the hated DIR blacklist??? :11:
or should that read DIR blacklist of hated devices to be more precise.

What does DIR diving or equipment have to do with it?

 

[String]

Aren't shoulder dumps on the hated DIR blacklist??? :11:
or should that read DIR blacklist of hated devices to be more precise.

Right... As if i care about that

Most BCs (hmm arent they off the list too!) have a right shoulder dump valve and a bottom dump valve in addition to the corrogated hose providing a means of dumping at any attitude. The corrogated hose is just a throw back to the ABLJ days and a relic that may well vanish from BCs in a while.

 

[d33ps1x]

Right... As if i care about that

Most BCs (hmm arent they off the list too!) have a right shoulder dump valve and a bottom dump valve in addition to the corrogated hose providing a means of dumping at any attitude. The corrogated hose is just a throw back to the ABLJ days and a relic that may well vanish from BCs in a while.

The only thing funnier than watching your guys troll is watching you do it in the New2Scuba section of all places.

You don't hear us cracking jokes about sheep tied to lamp posts AKA Welsh Town Centers do you?