User Guide and decompression information

[Zef]

I am not sure what you mean by the following:

"Just the idea that you have a "theoretical" ceiling makes it a bit more stressful."

If you are diving table with the intent (or not) to go into deco the table gives you a depth and time length for your stop....that is your "ceiling". If diving with a computer, it will indicate the depth and length of time for your deco stop(s)....that depth is the indicated ceiling.

Other than crediting you for off-gassing tissue compartments as you rise up through the water column during your ascent to the ceiling (or ceiling range), hence the notion of continuous decompression mentioned in the Vyper Air manual, there is really not much difference and not much to stress about if you plan your dive and dive your plan.

The Suunto Vyper and Vyper Air (as well as some of their other computers) have a dive simulation mode....you can run a simulation of whatever dive profile you plan including extending the dive past the no-deco limit and see exactly the what the computer will give you with regards to decompression obligation(s), ascent time (time to surface), and floor and ceiling depths. Should help reduce the concern you have...unless your concerns are something else.

-Zef

 

[DuboisP]

funny that a guy with 50-99 logged dives was explaining what's a ceiling to a divemaster having 500-999 logged dives

 

[Freewillow]

Hi Zef, we are in total agreement.

"My" theoretical ceiling is the same as yours. What I mean is that when you are in DECO mode the option of a RSA - go immediatelly to the surface in case of OOA - is not there anymore. You have you deco ceiling, a bit like you would have a ceiling on cave diving.

For some people, this makes a huge difference mentally. That is all of what I was trying to say.

 

[Freewillow]

Hi Zeb, did not realize that you were from Belgium. What town? TAke care.

 

[Zef]

You always have the option of heading directly to the surface, even during a decompression dive, and especially in an OOA situation....it just increases the risk of DCS. The Suunto dive computer will lockout in this situation as means to sway the diver to not dive any further that day whether they are experiencing DCS symptoms or not.

Given that, I am not understanding why having a computer that indicates a ceiling would increase stress....I imagine that if a deco dive was well planned, briefed, and executed, and still the diver found themself in an OOA situation then something really bad happened such as hose failure, entanglement, or other such emergency. In this case I would expect one of 2 possibilities:
1. The divers did a Rock Bottom gas management calculation as part of their plan/brief and should be able to share an air source to accomplish all decompression obligations and attain the surface safely.

or

2. The problem exceeded all planning expectations and were able to accomplish as much of their decompression obligation as possible before running out of air and then ascended directly to the surface.

In the case of latter, if the diver is worried about passing the theoretical ceiling indicated on their computer then I would say they should rethink doing deco dives.

-Zef
(I live near Blaton...send me a PM if you want to link up for a dive sometime)

 

[Freewillow]

You always have the option of heading directly to the surface, even during a decompression dive, and especially in an OOA situation....it just increases the risk of DCS. )

Zeb, I am not diving in Belgium, water is too cold for my old age.


Have you already deco dived? What is your dive level? I understand that DCS is better that plain drawning but
the statement that I am quoting from you hereabove is not compatible with my dive education.

As to becoming stressed when under deco obligations, I let you read some posts in this forum. Hopefully you will have another view on it . If PADI considers leasure diving to be within the NDL, this is for a very good reason.

 

[Zef]

I am certified NAUI Master Diver. I make a point to not go into decompression....in 21 years of diving I have never needed nor wanted to do so.

As to the comment you have quoted above, what you mention is exactly my point...."DCS is better than drowning". Even beyond the scope of DCS vs. drowning, a diver always has the choice to go to the surface even if/when it is not advisable. I am not recommending it.

In the context of my original comment, it was to point out that the "theoretical ceiling" is not a real/finite barrier to attaining the surface should a diver need/want to and is nothing to increase ones stress level about underwater just because it is displayed on one's dive computer.

Plan your dive, dive your plan, and train, train, train!!!

Have fun out there.

-Zef

 

[Bastianhund]

can one explain what the following terms are?

• Decompression floor
• Ceiling range
• Decompression range

For me a computor shoud give me, when in DECO mode, the depth/time of the deepest deco stop and the TTS ( time to surface). What are the other data that you would need? I am lost.

Freewillow,

Zef already did A great job explaining the terms above. However I encourage you to download the attachment I added to an earlier post in this thread. Please review the text. It will provide more accurate information. I believe it is important that all (Suunto) dive computer users are familiar with the information provided by the dive computer once the "No Deco Time" has been exceeded. Knowing the special rules related to the different Suunto RGBM algorithms can only make your diving more safe and enjoyable.

Also be aware of the differences between a "Safety Stop", "Mandatory Safety Stop", "Deep Stop" and finally "Decompression Stop". Violating each of those kinds of stops can have consequences in regard of how the dive computer let you do repetitive diving.

/Morten

 

[Zef]

If PADI considers leasure diving to be within the NDL, this is for a very good reason.

Freewillow,
If what you mean by "leasure diving" is synonymous with "recreational diving", then yes PADI and the agencies like it considers all recreational dives to be planned and executed within NDL parameters, barring a situation such as an emergency underwater that would cause a diver to surpass the NDL and require decompression stops during their ascent.

My understanding (based on my training and experience) of the philosophy in the world of diving is that recreational diving is generally considered to be down to a depth of -40meters (@ -132 feet) and within NDL parameters. Diving outside of these parameters is generally considered to be "tech diving".

-Zef

 

[Bastianhund]

It is important to understand that even PADI acknowledge a diver (using the Recreational Dive Planner table) could end up exceeding the NDL's. For this contingency the dive training organizations invented the "Emergency Decompressure Procedures". This is because once a diver (still using a RDP table) exceeds the NDL, the diver will not know the saturation status of his/hers tissues. This means the diver will now have to be very cautious when ascending i.e. decompressing i.e. going from depth to the surface. Special rules apply for such a situation. To simplify the rules a bit:

• The diver ascent to 5m with max. 10m per minut ascent rate.
• The diver remains at 5m until he/she has exhausted all available air supply from the diver himself/herself, the dive team and eventually a "Hang Tank".
• The diver then ascent to the surface and need to be monitored for DCS for maybe 24/48 hours before commencing with diving.

This is a logic approach as there is no useful information about tissue/compartment saturation once the diver exceeds the NDL's as outlined in various RDP's. It pays off to be careful. However: If this happens in your diving holiday you could be "banned" from diving even there is no danger.

The alternative is a dive computer. The dive computer keeps tracking tissue/compartment saturation even after the NDL's are exceeded. The data (information about the correct decompression procedure) provided by the dive computer must be interpreted correctly by the diver in order for the diver to ascent within safe limits........and avoiding the dive computer goes into error mode for 48 hours. Instructions on how to interpret the this data must come from the manufacture and must be clearly stated in the User Guides and Instruction Manuals. Suunto has removed this information from their UG's and I am still looking for a valid explanation from Suunto regarding this.

I do not encourage divers to exceeds NDL's unless specific trained in decompression diving procedures. I do teach recreational divers how to use their computers to their fullest potential. That means how to understand the information provided by the dive computer once NDL's are unintended exceeded. Once a dive changes from a "No Deco Dive" to a "Deco Dive" it is not necessarly an emergency. It could be an emergency if the dive team do not have enough breathing gas to carry out the decompression obligations. It could be an emergency if the decompression is carried out in the open ocean while drifting away from the support boat. It could be an emergency if the duration of the decompression obligations will cause the diver to go into hypothermia etc etc etc. From a physiological point of view the decompression obligations just add another set of risks to the dive. Most recreational divers are not aware of those risks and are certainly trained to handle them and minimize them.

My personal estimate is that approx. 95% or more of the recreational divers do not know how use their computer to their fullest potential. I am not the only dive pro who believes this number is correct. I will back up this number by looking at the very small amount of contributors to this thread. I have opened up a discussion about the very core functionality of the (Suunto) dive computers. Only a few of you seems interested in of taking part in this discussion. Many other subjects like questions about DM5, data transfer problems, USB cables and battery replacement seems to get a lot more attention. Why?

/Morten