Critique A Beginners Dive Profile

[The Chairman]

Per the Petrel manuel:

Safety Stop The Safety Stop setting can be set to the following values: • Off • 3 minutes • 4 minutes • 5 minutes • Adapt When using the Adapt setting, a 3 minute safety stop will be used, unless the dive exceeds 100ft (30m) or the NDL falls below 5 minutes, in which case a 5 minute safety stop is used.

This is an excellent adaptation! I might be setting my two Petrels to that.

 

[RandomGuy1]

I believe that particular setting is only available in rec mode though.

 

[Grey Goose]

Jax, you mentioned you try to do a 1 minute stop on ascent every 10 feet (following GUE). Is this not a 30 second stop and a 30 second slide to the next shallower 10 foot stop (albeit, GUE's SOP is a bit more specific: 30ft/min until reach 50% of depth, then 10ft/min, as outlined above; with a suggested (ie., not SOP) slower rate from 20ft to surface)? Either way, both methods are arguably more conservative than what is traditionally used.

One advantage of a 20ft (or 15ft stop) over (only) a 10ft stop is that it will be easier to stay under/correct a mistake if having a problem with buoyancy (particularly if waves).

 

[scubadada]

Hi Skeptic14,

Yes, your SAC/SRMV is quite high, >0.9.There are many threads aimed at helping newer divers improve air consumption. Experience and more dives certainly are important factors. I noticed you did your dives in a 3mm full suit, for 68 degree water, I would be wearing my 7mm, though cold tolerance is very individual. Your dives were quite short, is that partly because you were cold? For me, being cold is one of the major factors that increases my air consumption.

Good diving, Craig

 

[Jax]

Jax, you mentioned you try to do a 1 minute stop on ascent every 10 feet (following GUE). Is this not a 30 second stop and a 30 second slide to the next shallower 10 foot stop (albeit, GUE's SOP is a bit more specific: 30ft/min until reach 50% of depth, then 10ft/min, as outlined above; with a suggested (ie., not SOP) slower rate from 20ft to surface)? Either way, both methods are arguably more conservative than what is traditionally used.

One advantage of a 20ft (or 15ft stop) over (only) a 10ft stop is that it will be easier to stay under/correct a mistake if having a problem with buoyancy (particularly if waves).

Stop and slide is a newer method, but I am prone to fatigue, so I give it the full minute and 10 ft/min ascent.

I am very flexible, though. If the water is a bit sporty, I'll do a longer stop at 20.

 

[Jax]

I believe that particular setting is only available in rec mode though.

Ah! I admit to having only glanced at rec mode.

 

[Skeptic14]

Hi Skeptic14,

Yes, your SAC/SRMV is quite high, >0.9.There are many threads aimed at helping newer divers improve air consumption. Experience and more dives certainly are important factors. I noticed you did your dives in a 3mm full suit, for 68 degree water, I would be wearing my 7mm, though cold tolerance is very individual. Your dives were quite short, is that partly because you were cold? For me, being cold is one of the major factors that increases my air consumption.

Good diving, Craig

I believe the cold water definitely is part of my poor SAC. I estimate that my SAC is closer to .72, which still isn't good, when i'm in warmer water, but at the springs (68 deg) it's always pretty bad. The second dive was cut short because my dive buddy was cold and I was getting their myself. The first dive could've been a little longer than 31 minutes (800ish psi left) but was pretty close to the magic 500 psi coming out mark.

I suspect a 5mm would be more appropriate for 68 degrees for repetitive dives for me, but a 3mm already feels pretty restrictive to me and the majority of my dives I think will be in the 78-86 degree range.

I think another reason my SAC is high is I'm still over weighting myself and this is making establishing buoyancy harder as depth changes. With just 5 lbs I sank like a rock still and had to put a decent amount of air in my BC even with the full 3mm. I'm thinking fresh water I probably only need 3ish and salt maybe 4-5. I should've done a weight check at the end of one of the dives... hindsight...

 

[scubadada]

I believe the cold water definitely is part of my poor SAC. I estimate that my SAC is closer to .72, which still isn't good, when i'm in warmer water, but at the springs (68 deg) it's always pretty bad. The second dive was cut short because my dive buddy was cold and I was getting their myself. The first dive could've been a little longer than 31 minutes (800ish psi left) but was pretty close to the magic 500 psi coming out mark.

I suspect a 5mm would be more appropriate for 68 degrees for repetitive dives for me, but a 3mm already feels pretty restrictive to me and the majority of my dives I think will be in the 78-86 degree range.

I think another reason my SAC is high is I'm still over weighting myself and this is making establishing buoyancy harder as depth changes. With just 5 lbs I sank like a rock still and had to put a decent amount of air in my BC even with the full 3mm. I'm thinking fresh water I probably only need 3ish and salt maybe 4-5. I should've done a weight check at the end of one of the dives... hindsight...

I have a 3, a 5 and a 7 mm full suit at my home in Boynton Beach as well as a 5/3 hooded vest. I dive all year round and use all of the suits to cover water temps from the high 60s to the 80s

 

[Carl_F]

From the different answers being provided, it should now be clear that there is no one recommendation for maximum ascent rates or safety stops. Each agency has it's own recommendation. If you stick to how you were trained, you will, in all likelihood, be ok. As you gain more experience and knowledge, you'll be able to better assess whether and how to deviate from your initial training (hopefully to the conservative side ... I'm not recommending deviating to have faster ascents or shorter safety stops.)