Overshooting NDL and mandatory deco stops

[scubadada]

Thanks @Diving Dubai, your wife has a very low RMV

 

[Mike1967]

my consumption is "rubbish" approx 14l/m

 

[atdotde]

I would expect lung size to be the defining factor: you only metabolize a couple of % of the O2 in the air, the rest goes in and out of the lung. Height would be a proxy measure for lung size.
)

you are right, it‘s not O2, but it’s CO2 that triggers breathing. And that is proportional to metabolism. My guess would be that fat vs. bone vs. muscle and male vs. female are secondary effects once weight has been taken into account (which of course differs between men an women).

 

[dmaziuk]

you are right, it‘s not O2, but it’s CO2 that triggers breathing. And that is proportional to metabolism. My guess would be that fat vs. bone vs. muscle and male vs. female are secondary effects once weight has been taken into account (which of course differs between men an women).

@rsingler ?

 

[Blackcrusader]

So do all those things you were taught, to relax and streamline. Breathe fully (not shallowly) to minimized dead-space ventilation, and accept what you get. We just can't all be like @scubadada and Crusader, sad to say.

My dive buddy who took this video of me has around the same air consumption as I do. We do a few dive vacations together each year. Probably I will get in 50% more dives per trip as he is not an early riser. This was in Panglao in Bohol Philippines depth around 30m or so. Just plodding along following another friend of mine who work there. You can see I leave lots of bubble exhale trails every now and then.... more of less 15 - 20 seconds...

 

[scubadada]

Hi @BLACKCRUSADER

Have you ever calculated your RMV?

 

[Blackcrusader]

Hi @BLACKCRUSADER
Have you ever calculated your RMV?

I did a long time ago for my BSAC sports diving. Back in the 80's there were no dive computers, so planning dives meant being far more meticulous as you had to bring dive tables to calculate your time for deco stops. Knowing your RMV was required as we used 15l steel tanks with 230 bar in the club I dived with. I've forgotten what it is.

For me diving is relaxing.. I'm probably more relaxed under the water than out of it.
Also with no one to talk to underwater I don't have the same air consumption as out of the water.

 

[Blackcrusader]

It's been almost forty years since I was on a university medical faculty, so I'm the wrong person to ask, lol!

I'm going in for intraocular lens replacement in my eye tomorrow. Had the pre op examinations last week. Have ask to see if the person doing the anaesthesia can check my RMV.

 

[rsingler]

Have ask to see if the person doing the anaesthesia can check my RMV.

It's interesting, but I can't really relate it to my diving. As you saw in the post above, my "in the chair" mellowed out RMV was 5.1 l/m, yet the lowest total RMV I've ever recorded on a dive is 10.6 l/m, and most are around 17. Adding any exercise completely changes the picture.
But yeah, it's interesting to measure, just for background. Ask him to hand you the connector to the mask (don't use a mask - it's too hard to get a perfect seal), put it in your mouth and lie there breathing only thru your mouth and see what he reads on his machine.

 

[Heat Miser]

To the OP, I started to read all 34 pages of response, but failed....To the extent you asked this question because you have a Perdix AI .... When the Perdix AI is set to Adapt for a Safety Stop, generally 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.... It can be quite confronting when you first see it happen and you haven't RTFM (as someone prior put it) ..... However if you asked the question because you regularly push your NDL limits, then I no longer pity you.

As a side story, I was in the Maldives over the New Year period. and diving with 2 Instructors, 1 AOW candidate, her Dad, and myself. It was the second dive of the day, to 30m depth and all of us except the AOW Candidate where on 28% Nitrox. The lead instructor tells the candidate to watch out for her NDL, and she's on Air. The candidate forgets to so. Both instructors forget to do so and yes she overshot her NDL. So my new rule of thumb is whenever I hear a beeping alarm, even if I know its not mine, even if I'm with someone more experienced than me, like the two instructors. Make certain to find out who's alarm it is, question what the problem is and that they are OK and encourage them to take remedial action. The AOW candidate was put into an extra 2 min safety stop, i.e. 5 Min in total, by her dive computer which was a Cressi.