How well do you hold stops?

[lostcajun]

I like to watch my computer and practice improving my buoyancy skills....

 

[DevonDiver]

i don't think anyone had any doubt in their mind that your intention was to ridicule PADI. Even now you are not being factual. PADI recommended making a vertical ascent along an up line. It is not a general recommendation for all safety stops. It does get old.

Post #38 provided reference to the PADI Deep Diver Instructor Outline, where the theory content for deep diving safety stops is clearly and unambiguously explained. I suggest you contact PADI directly if you have an issue with it.

In case you doubt the veracity of the reference I have given, the picture below is a screenshot of the relevant page in the PADI Deep Diver Instructor Outline. It is the actual presentation outline, the information which it contains must be given to students (as referenced in Post #46). Interpret it however you desire, I have no desire to debate the reference with you. I think it is amply self-explanatory.

That's about as factual as it gets - a direct image from the relevant instructor course outline. Please note, I have offered no personal opinion on this technique, nor attempted to ridicule it. I have merely agreed with you that vertical position for safety stops is not my personal preference as a diver and instructor. I am glad that we (PADI Instructors) are not forced to apply this approach practically (on training dives), because it is not mandated in the performance standards for training dives. I enjoy the flexibility to teach safety stops, on the Deep Diver and other PADI courses, in horizontal trim.

Students often seek an explanation why I teach horizontal stops practically, when the theory lesson (and PADI Deep Diver video , see below) illustrates the use of a vertical position. The only way I see to explain this is that the vertical position allows students to supplement propulsion for buoyancy and to enable the diver to turn/see around more easily. The PADI course does not assume that all/most students will have mastered skills like horizontal trim and the helicopter turn. My students do... which enables them to hold the stop whilst retaining buoyancy, trim, maneuverability and situational awareness.

When deep recreational diving, with a higher level of on-gassing, it is prudent to retain the option to 'hold the line' and/or remain vertical, if that provides a greater assurance that the diver will not lose buoyancy control in the shallows. However, the diver should, IMHO, aspire to developing the skills necessary for a controlled, and protracted, accurate stop in horizontal trim. Those skills should be developed on shallow dives initially, before the diver is 100% confident of applying them on more aggressive, DCS-risky, dives. Needless to say, I believe that this level of skill should be a mandatory expectation of tech-level divers.

This is the PADI Deep Diver course video. The section on safety stops ("Deep Diving Ascents") begins at 14:30....



In respect to the initial TecRec courses (Tec40/45/50), PADI apply the following performance standards in respect to stop depth accuracy:

Tec40 Dive #1 - 4 - within "approximately .5 metres/1.5 feet", maintaining a "roughly horizontal position with their chests at stop depth".

Tec45 Dive #1 - "students to use neutral buoyancy to remain within .5 metres/1.5 feet of stop depth".
Tec45 Dive #2 - "students to stay plus or minus .5 metres/1.5 feet of the stop depth and generally horizontal, stop depth at chest level".
Tec45 Dive #3 - "not varying from the stop depths by more than .5 metres/1.5 feet" and, later, using the backup buoyancy control system alone, perform the gas shutdown drill without varying from stop depth more than 1 metre/3 feet (no time limit)", also including a neutrally buoyant gas shutdown drill at last stop...plus or minus 1 metre/3 feet of stop depth".
Tec45 Dive #4 - No performance standard stipulated for decompression stops (actual deco dive).

Tec50 Dive #1 - "students to use neutral buoyancy to remain within .5 metres/1.5 feet of stop depth".
Tec50 Dive #2 - "students to use neutral buoyancy to remain within .5 metres/1.5 feet of stop depth" and "conduct the gas shutdown drill using only buoyancy control to remain within 1 metre/3 feet of the stop depth".
Tec50 Dive #3 & 4 - No performance standard stipulated for decompression stops (actual deco dive).

In a nutshell, the Tec40/45/50 standards are:

1) Trim should be "roughly horizontal position"
2) Deco stop accuracy should be "within .5 metres/1.5 feet of stop depth".
3) Minimum accuracy when practicing redundant buoyancy and/or shut-down drills should be "within 1 metre/3 feet of the stop depth".

I feel that these stop depth deviation limits are an acceptable minimum as training standards. I also feel that instructors/students should aim for greater performance than the lowest acceptable standard. In this case, I aim for students to maintain, at least, half the variation allowed... but aim for a precision of +/-10cm (+/- 25cm when task loaded/doing drills unsupported).

As an off-topic aside - the variance in approach and outcome between the Deep Diver and Tec40 course is so great, I hardly teach the Deep Diver course any more. The entry prerequisites are virtually identical, with the exceptions that Tec40 requires EANx qualification and experience of "10 dives below 18m" (in lieu of a Deep Diver qualification). Tec40 makes a very nice recreational deep diving training program.

 

[TSandM]

I'm shaking my head in disbelief. Has anybody ELSE noticed that this is in the Technical Diving subforum? What on EARTH do PADI standards or PADI instruction for the deep diving course have to do with this thread?

 

[DevonDiver]

I'm shaking my head in disbelief. Has anybody ELSE noticed that this is in the Technical Diving subforum? What on EARTH do PADI standards or PADI instruction for the deep diving course have to do with this thread?

The side-issue of stop position was raised by RJP in post #33.

Stop position (vertical/horizontal/variations of..) might be deemed a criteria in answering the over-arching question "how well do you hold stops?".

Deep diver training is a prerequisite for TecRec (technical) diving courses. The Deep diver course educates (theory lesson/video) that stops should be held vertically. This goes some way to explaining why some divers at advanced/technical levels may have a preference for vertical stops. It also raises interesting discussion points as to why vertical or horizontal stop position may be preferable/optimal.

The TecRec standards quoted provide one agencies' baseline performance expectations for stop accuracy and conduct. This provides some context.

 

[rongoodman]

I'd forgotten how truly awful those PADI videos were.