Dumb question, but... how deep can you go?

[Vicko]

10 years ago 120m was considered a rare and serious dive, now it's done every day. Even 150m have become "usuall".
But reading the incident reports and talking to some of the deep divers there's a figurative wall at around 160-180m that keeps killing a lot of people.

 

[DiveLikeAMuppet]

The machine is not the limit, it's the human, especially if the person intends to survive these dives repeatedly. You would be looking at running a dive expedition and your depth limit would depend on risk tolerance of everyone involved and your budget.

Diving in a cave? You can (probably) have a deco habitat, (probably) rule out poor weather, if required you could supply massive amounts of gas, barbecue for support divers, alert a hospital in advance, have a chamber ready etc. You still have all the cave diving risks and if something happens at depth, there is no rescue.

Diving in the ocean, unknown wrecks, cold water? Your limit will be how much deco can you safely run vs. how much can you accomplish during your bottom time - can you survey a site covered in fishing nets in poor visibility in 10-15 minutes, because that's all you get at 100-120ish meters for the price of 3 hours of deco? Can you find the right skipper with the right boat and the right experience? Can you get a team of people who dive these depths to dedicate a specific week to checking out few unknowns because weather happens? How quickly can you get a helicopter to the site to evacuate a diver and how long to a chamber? Can you have a doctor onboard? You don't even need a big emergency - think how long can you survive in cold water with a leaking drysuit and how efficient would be those 3 hours of very cold deco?

A lot of the hobby CCR diving is way riskier than we all want to think, that's why some of the informal exploration teams have a trail bodies and badly bent divers behind them - a commercial operation would have a chamber onsite and would run these sites with an ROV or as a saturation dive.

 

[broncobowsher]

Most every CCR will list it is rated for 100m. In general they will easily do double that.
As noted, it really isn't the rebreather that is the limitation. Endurance is the issue. That deco time racks up really fast.

You mention recreational rebreather. That has the same limitations as recreational open circuit. You can get a little more time, simply because you are doing Nitrox optimized for every depth. But that doesn't add depth, only time. A rebreather is a Nitrox blending machine you dive with.

Want to get a little beyond that, get into planned deco diving, there are training phases. First step, generically called MOD 1 (module 1?), gets you recreational 100' no deco rating. If you have a good background your instructor may give you a little more, upwards of 150' and some deco on air. Minimal bailout. Rebreather training wheels.

After that is MOD2, a 200' rating. 2-stage bailout. Pretty common rebreather rating. Easy enough to spend several hours on a single dive, mostly hanging out on the deco line. This will get you a lot of places.

MOD 3 is 100 meter rating. Hypoxic (very low oxygen) diluant gas. Lot of bailout and planning. Some rebreathers will take very minor modifications to work at this level. Beyond that, there isn't any official training. People do it. By this point you have enough education in deep rebreathers that you figure it out yourself. Dive with others who have also figured it out. Cross reference with others in the pool.

Personally, I only have a 200' rating. I know of what it takes to get that 100m cert, don't really plan to do it.

 

[happy-diver]

A machine as it comes out of the factoy has not much to do with much



What you need is a particular psychology and sense of humour which may develop with time

N=1: The Inside Story of the First-Ever Hydrogen CCR Dive

On Valentine’s Day, Dr. Richard Harris, aka ‘Dr. Harry,’ and the Wetmules made the first reported hydrogen (H2) rebreather dive to a depth of 230m/751 ft, in The Pearse Resurgence, New Zealand. The 13 hour dive, which was nearly two years in planning, was a field test to determine the efficacy...

gue.com

 

[lostsheep]

Saturation diving can go deeper, and would be the next step after rebreathers 300-ish limit. Down to 2300 feet.

No one is actually doing 2300’ dives.

 

[PEDiver]

No one is actually doing 2300’ dives.

Those were chamber dives done by Comex IIRC. I don't believe many sat divers go below 1000' in the course of the job.

 

[boulderjohn]

Some people call the area between typical scuba and ROVs "The Twilight Zone.

Diving Deeper: How Scientists Use Rebreathers For The Ocean's Twilight Zone » Explorersweb

In between the sun-soaked reefs of the shallows and the weird depths of the deep sea lies yet another marine world full of secrets: the mesophotic zone.

explorersweb.com

One of the most famous divers of the twilight zone is ichthyologist Richard Pyle. He has demonstrated a potential danger in such diving--temporary Tourette Syndrome.

 

[sea_ledford]

The controller and the battery compartment are the only parts of a CCR that aren't at ambient pressure, so they'll go as deep as those two spaces have integrity. I suppose there would also be a limit on spring strength in the first stages, even if they aren't fixed. I don't remember the depth rating on a shearwater... 250M or something like that? But that is the depth rating, not the crush depth, it'll probably work fine for a bit deeper than that. I would guess by about 300M you'd be getting into the physical limits of the unit itself.

Or as my first CCR instructor told me, "this machine will happily take you on a dive that you have no hope of surviving."

 

[MidOH]

No one is actually doing 2300’ dives.

The record saturation dive is exactly that.

701 meters.

 

[lostsheep]

The record saturation dive is exactly that.

701 meters.

No it’s not.

I believe you are talking about hydra 10, which was on land in a chamber.

Hydra 8 was actually in the ocean but “ONLY” ~530m