To ADV or not to ADV

[Depth-junkie]

Originally Posted by nigelH

So explain why I need to shut it off then?

i did, read the whole post. But heres a snippet:-

The reason for switching it off, is to stop any ADV leak causing a problem. Also allows you to maintain min loop better/easyer when off gassing like mad into the loop for the 1st 20-30min of monster deco @ 6m with no possible way for the ADV to fire adding Low po2 gas to the loop causing big swings in PO2 when the loop is already all over the place for a bit when off gassing from big dives. Also means from 6m up and surface swims back to the ladder, climbing back up the ladder etc the only thing i put in my loop is 02 or DIL by my own manual actions and not accidentaly by a big suck causing the ADV to fire. And from 9m up the only thing that goes into my loop is pure 02

ATB
Gareth

[nigelH]

Originally Posted by Ferg3333

But then I maybe wrong and other options are available

I still see no reason for turning it off.

I'm getting more perplexed. So I have a hypoxic dil available at 3m? I have pure O2 at 60m but I don't push the button. The whole reason for an ADV is to simplify things both in normal diving and in problem situations. If I am shallow and descend a bit my loop is already very rich so a bit of dil isn't going to kill me but if I am already solving one problem I don't need to reach for a button to solve another. In the, thankfully few, times I have had a problem in the water the one thing I didn't have was a spare hand. I can picture the poor guy with a sinking buddy in one hand, the shot line in the other and flat counterlungs.

I think we're just going to have to disagree in which case and ADV probably isn't worth you having as all the advantages I think get won't be available to you if you switch it off. It's hardly worth it just for a hands free descent.

[Ferg3333]

Originally Posted by nigelH

I still see no reason for turning it off.

I'm getting more perplexed. So I have a hypoxic dil available at 3m? I have pure O2 at 60m but I don't push the button. The whole reason for an ADV is to simplify things both in normal diving and in problem situations.

I understand what you are saying and I think I have made my mind up now. Cheers

[NotDeadYet]

Originally Posted by nigelH

I still see no reason for turning it off.

I'm getting more perplexed. So I have a hypoxic dil available at 3m? I have pure O2 at 60m but I don't push the button.

A big inhale isn't going to fire O2 straight into the loop though is it? I shut mine off for the same reason, I don't want hypoxic gas when I'm at or near the surface. Even on what feels like a generous lung volume I can still trip the ADV on a big breath. It doesn't take a massive amount of effort to burn enough O2 off to reduce the volume enough to trip the ADV either, I've done it walking up a steep bank which was probably a similar amount of effort as finning hard. Certainly on the CK it can have a bit of hair trigger depending on your position in the water too.

[Depth-junkie]

Originally Posted by nigelH

I still see no reason for turning it off.

I'm getting more perplexed. So I have a hypoxic dil available at 3m? I have pure O2 at 60m but I don't push the button. The whole reason for an ADV is to simplify things both in normal diving and in problem situations. If I am shallow and descend a bit my loop is already very rich so a bit of dil isn't going to kill me but if I am already solving one problem I don't need to reach for a button to solve another. In the, thankfully few, times I have had a problem in the water the one thing I didn't have was a spare hand. I can picture the poor guy with a sinking buddy in one hand, the shot line in the other and flat counterlungs.

I think we're just going to have to disagree in which case and ADV probably isn't worth you having as all the advantages I think get won't be available to you if you switch it off. It's hardly worth it just for a hands free descent.

when i say Hypoxic DIL's im talikng about the likes of 6/65 or 10/52 here, and not the lieks of 18/40 etc.

If you cannot see the need to close of the ADV shallow when running theses types of gas's you are obviously not using these DIL's and inturn not incuring the big deco that you get with dives that warrant these DIL's(off gassing into the loop causing big PO2 swings, lungs inflating by the off gassing during deco followed by the unit adding 02 trying to stabalise the PO2, you venting to maintain min loop vol)

Anyone who has done dives with 3hrs+ deco knows how unstable the loop PO2 is for the 1st 20-30mins of deco @ 6-9m. The last thing you need/want to make the PO2 swings even worse is a inadvertantly fire of the ADV with 6/65 DIL. And as for surface swims etc it speaks for itself.




ATB
Gareth

[NotDeadYet]

Originally Posted by Depth-junkie

Anyone who has done dives with 3hrs+ deco

First time I did a 3hr dive on my lump (the 2nd ever dive on it ) I was really surprised at how hard it was to keep the loop over 1.4 when you hit the final stop. I ran out of O2 trying to keep it high. Almost makes me think you'd be better off decoing on OC oxygen on long dives.

I'm sure someday the computer will be able to monitor your deco by watching how much you're offgassing into the loop.

[Juz]

Originally Posted by Depth-junkie

when i say Hypoxic DIL's im talikng about the likes of 6/65 or 10/52 here, and not the lieks of 18/40 etc.

If you cannot see the need to close of the ADV shallow when running theses types of gas's you are obviously not using these DIL's and inturn not incuring the big deco that you get with dives that warrant these DIL's(off gassing into the loop causing big PO2 swings, lungs inflating by the off gassing during deco followed by the unit adding 02 trying to stabalise the PO2, you venting to maintain min loop vol)

Anyone who has done dives with 3hrs+ deco knows how unstable the loop PO2 is for the 1st 20-30mins of deco @ 6-9m. The last thing you need/want to make the PO2 swings even worse is a inadvertantly fire of the ADV with 6/65 DIL. And as for surface swims etc it speaks for itself.




ATB
Gareth

My gas of choice is 10/70 and I agree completely with Gareth. Also, the only way to get a proper O2 flush is to have the ADV shut off.

Juz

[stewybear]

Hi,

As a newbie to RB diving, and only having 45 dives on my unit so far, I found it really nice to have the ADV on decent but I have adopted isolating it when at target depths because it aids minimum loop volume. Any further additions are made using the button on the CL.

I found that when isolated, its a good indicator that your depth is changing because a short breath means your have decended and a longer one means your are ascending.

Never gave the trimix issues any thought because I have not reached those dizzy heights (or is it depths ) yet. I'm sure it will come sooner or later though .

Regards
Stewart