Computers and Decompression ????????

[canadascuba]

Hello to all out their I am a newby to scuba board and i have never done this before but I have lots of Questions So here goes !
I have a Mares M1 "RGBM" Wrist Computer and I have been playing around in the sim mode it says that if i do a 140 foot dive on air I need to make 1 min deep stop at 60' and only a 4min deco stop at 10' is this true it seems to be very liberal to me any thoughts?

 

[Soggy]

Hello to all out their I am a newby to scuba board and i have never done this before but I have lots of Questions So here goes !
I have a Mares M1 "RGBM" Wrist Computer and I have been playing around in the sim mode it says that if i do a 140 foot dive on air I need to make 1 min deep stop at 60' and only a 4min deco stop at 10' is this true it seems to be very liberal to me any thoughts?

140 minutes for how long? if you only spend 2 minutes there, that might be ok, but 30 mins would require about 50-60 mins of decompression.

 

[canadascuba]

Sorry I meant to mention that is was about 5 min but also what about deep stop I thought I read somewhere that it had to be at 80% of the max depth that means a 100' foot dive would be a stop at 80' is this right?????

 

[canadascuba]

Also what have you heard about theses computers are they ok to trust

 

[Soggy]

Sorry I meant to mention that is was about 5 min but also what about deep stop I thought I read somewhere that it had to be at 80% of the max depth that means a 100' foot dive would be a stop at 80' is this right?????

The 80% ATA 'rule' isn't applicable for all dives of all durations. It certainly would not apply to a 5 minute bounce dive on air to 140 ft. To be honest, for a dive that short, almost anything will get you out of the water just fine. It'll probably take you 3 of those 5 minutes just to get to depth, leaving you with 2 minutes at depth.

Also what have you heard about theses computers are they ok to trust

You should never jump in the water and just trust that your computer will give you the correct profile. Diving to 140 ft on air with no deco gas while following the bouncing ball of your computer would be less than intelligent.

Additionally, diving beyond 130 ft or staying at depth long enough to accumulate a decompression obligation is a really bad idea unless you have had proper training and understand the risks involved.

For the record, this is the schedule that Vplanner produces for a 5 minute dive to 140' on air:

Decompression model: VPM - B

DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 1

Dec to 140ft (2) Air 50ft/min descent.
Level 140ft 2:12 (5) Air 1.10 ppO2, 140ft ead
Surface (9) Air -30ft/min ascent.

This basically amounts to that dive having no mandatory decompression, but any deviation from that plan, unintentional or otherwise, would.

 

[canadascuba]

thank you very much ! I am very interested in deco I just bought my first set of doubles and a backplate, harness i am waiting to start the couse though padi teckrec do you have any sujestions for reading ! somthing good for teck wantabies like myself not to complex but a good intro

 

[Rick Inman]

I have a Mares M1 "RGBM" Wrist Computer and I have been playing around in the sim mode it says that if i do a 140 foot dive on air I need to make 1 min deep stop at 60' and only a 4min deco stop at 10' is this true it seems to be very liberal to me any thoughts?

Just a little heads up on the M1 RGBM, anytime you incur a deco obligation, the M1 adds 2 mins to your "safety stop", giving you a 5 min SS on top of any obligation. In other words, on the profile you mentioned, after you do the 4 mins at 10', the M1 will then tell you you do a 5 min safety stop as well.

Reality is, on the dive you mentioned, assuming you do a nice slow ascent, by the time you hit 20', the M1 will have forgiven you the 4 min hang and, bingo, you'll end up with the same profile as V planner.

Which is why I run the thing in BT mode!

 

[daniel f aleman]

Point is that the Mares M1 Wrist Computer is used some of the best Tech divers in the world, and the unit uses the NAUI, now standard, "RGBM" tables.

The definitive website on RGBM:

http://www.rgbmdiving.com/

 

[terrasmak]

thank you very much ! I am very interested in deco I just bought my first set of doubles and a backplate, harness i am waiting to start the couse though padi teckrec do you have any sujestions for reading ! somthing good for teck wantabies like myself not to complex but a good intro

Some quick good advice , dont take there course. There are much better ones out there that are safer and teach better stuff .

 

[matt_unique]

I'm not familiar with the computer you are referring to. Most computers are not at all relevant for deco diving with a few exceptions (VR3, etc,). It's a common misnomer that recreational computers, that happen to provide deco obligations should you violate NDL's, are usable (or even remotely safe) deco computers. Most deco divers use software such as V-Planner or Deco Planner to plan deco dives and copy these profiles to slates and use computers only as backup or for just a time/depth device.

The course you take for deco training is almost irrelevant in comparison to your instructor. There are some excellent PADI Tec Wreck (or perhaps it's called Deep Tec) instructors who would provide an excellent course. It's said often on SB but the agency stamp on the card is irrelevant in comparison to the instructors name.

--Matt