Next step for longer bottom times on deep dives?

[rolanddiver]

I never said that he should get a rebreather just because he can afford it. If he wants longer bottom times, less deco obligation than the CCR is the way to go. Eventually he would end up diving one anyways, so why not save the time/cost of OC trimix and get the right tool for the job. Before someone asks, yes I have been diving a rebreather in caves since 2007 and I actually built both of them and I'm still alive.

Very Respectfully

Roland

 

[grantctobin]

Wrong on 2 counts but hey who needs accuracy when it makes for a dramatic attention getting post.

I'm only rec certified, never took a tech class.

I let my main tank get lower than most due to having the reserve in the pony

I don't think I've ever taken a breath off my pony bottle.

That gives me more time without the time and expense of the tech classes and any additional gear.

I don’t typically start to ascend with more than 500 psi in my main tank since I’ve got the large reserve in the pony.

Diver A is your typical single tank AL80 diver, returning to the boat with anywhere between 500-750 PSI.

Diver B has an AL80 plus a second completely redundant 30cf tank. Diver B returns to the boat with between 50-100 PSI in the main tank PLUS a completely full 30cf pony bottle.

Diver B has the safety of redundancy throughout the entire dive plus he returns to the boat with more gas than Diver A.

Diver B is in a much safer position and LESS likely to have an OOA situation than your typical Diver A.

I started with a Spare AIr maybe 10-15 years ago, then upgraded to a 19cf pony bottle and now I carry a 30 ct pony bottle.

You say that you always start your ascent with 1000 psi. When carrying a pony bottle I cut my main tank reserves roughly in half, so I'll start to ascend at around 600 psi and maybe have 300 at my safety stop and surface with 50-100 psi.

I've got the reserve in the pony tank so it allows me to draw my main tank gas lower, giving me extra gas on virtually every dive plus the safety of the redundancy of the second independent tank and regulator.

 

[flymolo]

I never said that he should get a rebreather just because he can afford it. If he wants longer bottom times, less deco obligation than the CCR is the way to go. Eventually he would end up diving one anyways, so why not save the time/cost of OC trimix and get the right tool for the job. Before someone asks, yes I have been diving a rebreather in caves since 2007 and I actually built both of them and I'm still alive.

Very Respectfully

Roland

I think if you can easily do the same dive on OC a rebreather is not the right tool for the job. It’s a lot harder to get hypoxic, hyperoxic, or hypercapnic on OC than it is on CCR.

Also, at those depths CCR and OC will have very similar decompression obligations,

 

[flymolo]

Thanks for saving me the trouble of retrieving my old posts to point out your two blatent errors in regard to my posts, in an attempt to create unnecessary drama.

If you're bored, go diving.

it seems somewhat irresponsible to suggest someone start doing decompression dives without proper training or equipment

 

[flymolo]

I'm not suggesting they do it. I'm simply explaining what I do.

I understand that. However I'm saying that another reader might see your post as confirmation that it's safe and practical.

 

[flymolo]

I don't really consider it to be unsafe and for practical purposes it gives me a few extra minutes of bottom time.

Of course. But you don't know what you don't know.

 

[Angelo Farina]

You do not nessarily need to enter the tech world. Here in Europe recreational divers are usually trained to "light deco" rec diving.
This means not exceeding 50m depth and going sligthly beyond the NDL, so that you need something as 20 min max of deco stops, which are usually done on "back gas".
Here the standard back tank is 15 liters at 232 bars, which is plenty enough for such light deco profiles.
Of course some redundancy is always advisable. The minimum is two independent regs using a tank with two valves.
Better instead to use a pony tank.
Even better a compact twin (8+8 liters at 232 bar, or 10+10 at 200 bar).
All this is still considered fully recreational here, and is included in normal third level training (that is certifications coming after advanced open water).
In my personal opinion, these light deco dives are much safer than dives "just within" NDL.
A light deco dive is planned and executed with a proper amount of gas, with some redundancy, and with tools for facilitating proper deco stops (such as bars hanging below the boat at 6 and 3 m).
Instead a dive "just within NDL" is usally executed with a single small tank, no redundancy and no support for deco stops. When **** happens, you are suddenly beyond NDL, without all these additional safety measures. This requires a mandatory deco stop, but instead of being a planned, safe stop, you are in an emergency situation...
So I think that before stepping up in the world of tech diving, you should evaluate the possibility of staying in the rec diving world, simply getting the training and the equipment for doing some reasonable amount of deco.
I was always fully satisfied of this and I never felt the need of going tech...

 

[Mike1967]

AN/Helitrox

 

[100days-a-year]

Sweet, I've always considered .myself a bit of a deviant.

In this case though, since the far majority of the dives we're discussing are done on air or nitrox and historically have been, the " deviants " are those who seem to lack the intellectual abilities at depth to dive like the rest of the world and need helium to do so. No shame but I certainly would be thumping my chest about this inability.

The answer to " what color are trimix bubbles ? " is koolaid colored <130' OR
" How do know if someone is diving a helium blend within recreational limits? "" Don't worry, they'll tell you "

 

[doctormike]

I never said that he should get a rebreather just because he can afford it.

"If your budget permits, get a rebreather."

If he wants longer bottom times, less deco obligation than the CCR is the way to go.

I think that he just said that he wanted longer bottom times. AN/DP with OC would be fine for that.

Eventually he would end up diving one anyways, so why not save the time/cost of OC trimix and get the right tool for the job.

Why do you assume that someone whose original request was to spend more time on wrecks in the 90-130 foot range would eventually end up on CCR?