Rebreathers: Semi-closed or fully-closed?

[wetpixel 0]

Hey, guys. I've done a couple of exploratory dives on Drager Dolphin semi-closed rebreathers, and plan to get certified for semi- or fully-closed rebreathers this coming January. Any advice on:

 

Semi- vs. Fully-closed?

 

Brands/models of each type?

 

I will not be purchasing a unit in the near future, so I will likely be renting what I can, where I can. This probably rules out closed-circuit units.

 

I also do not want to die, and would prefer something with a good safety record.

 

Thanks for any help you might be able to provide!

[MikeO 5]

While its a bit late for you in this case, this looks like a good way to get certified:

 

http://www.fathomspub.com/expeditions.cfm?id=5

 

Mike

[tshepherd 0]

Eric,

 

One of the guys that went on my Truk trip this year, works as a mate on a local boat, and has done over 100 dives to the Andrea Doria uses a closed-circuit rebreather. I believe it's the Inspiration maybe. It's a Trimix capable setup, costs more than a 1Ds, and is very hard to take on the road, as it weighs over the 70 lb limit.

 

Another couple of guys I dive with have the Drager semi-closed versions (dolphin maybe?), but rarely ever use them.

 

The biggest PIA is that they require a lot of maintenance, more than open circuit, and it has to be done right after the dive, so doing multiple dives in a day can be tedious, especially when you're also maintaining a camera rig.

 

You're more likely to be able to get support in remote places for semi- than closed-, as there just aren't a lot of closed- out there.

 

That being said, they are very cool.

 

 

Pete, pictured above, was constantly scaring the cr@p out of people by popping out of wrecks. He could get closer to any type of fish than anyone by a long shot.

 

If you're going to try it out, I'd head to somewhere like Grand Cayman with Divetech to do it. They've got training courses and rentals, and are in a good place to test drive a rebreather.

 

If you want, I can put you in touch with Pete W via email. He's more than happy to talk about his setup and his experience. He's also running a trip to Truk for 10-14 days next year where he'll be bringing his rig again.

 

Hope this helps.

Tom

[Dave H 0]

Many of my buddies dive on rebreathers, there is a pretty good discussion forum here in Oz that might have some useful info:

 

One of mate's recently purchased a KISS Rebreather from Canada and it appears to be one very sweet unit.

 

DiveOz Rebreather Forum

[donauw 0]

Eric -

 

I've been diving the Drager Dolphin for more than two years (about 250 dives now) and use it extensively. I love the unit. It is relatively simple and has is all mechanical (no electronic controls - although I do have an oxyguage that monitors the PO2 in the breathing bag).

 

I have been impressed at how much easier it is to approach marine life with the unit. I get about two hours of bottom time on a 27 cf tank (using 40% Nitrox which breathes down to about 32%).

 

I am based in the Florida Keys and the Great Lakes and use the unit extensively in both locations (including with dry suit). If much of your diving/photography is an area where you can get support for the unit - then it is worth it. If you are only going to travel with it...then I'm not so sure.

 

Travel with it, however, is no more difficult than with open circuit IF you are going to a location that supports the Dolphin. (There is generally an operation that has tanks, mixed gas for, and has scubber absorbant in many major dive locations). I traveled with mine to Grand Turk several months ago and routinely transport it between Florida and Wisconsin. (Local shops in both locations support the unit)

 

You must, however, be METICULOUS with the unit. It takes about 15 minutes extra predive and about the same postdive in preparation and maintenance.

 

I would advise starting with the Dolphin. After getting comfortable with it, then it may make sense to move to a closed circuit system - depending on your diving. I plan to certify on the Inspiriation next year - mainly because I just want to. Not because I feel it will give me any photo advantage over the Dolphin.

 

Regards,

[donauw 0]

I'm on the Adolphus Busch wreck in the Keys...buddy has my camera...

 

You almost have to push the schooling fish out of the way when you are diving the rebreather.

 

 

Regards,

[Ychng 0]

Also consider the Azimuth if you are definitely going the SCR route. It doesn't have the tiny mass-flow orifice of the Dolphin that gets clogged by salt crystals and the like.

 

My place to get information about RB's is the Rebreather section of www.scubaboard.com. Lots of RB divers and instructors hang out there, including padiscubapro (Joe Radomski), a Inspiration instructor from the NY area.

 

I'd love to get my hands on the new Inspiration Evolution. It uses 2 ltr cylinders rather than the 3 ltr cylinders on the current Inspiration. Limited to 2 hours total dive time as opposed to 3 on the current Inspiration, due mostly to scrubber limitations. It's coming out next year at about 7-9k and is smaller and lighter than the current inspiration, which would address some of the weight issues that Tom brought up. Mixed gas computer built in too, so you don't have to fork out for another VR3 or HS Explorer.

 

If I were to go RB, I'd go CCR -- there are too many advantages in favor of going closed circuit over the currently available SCR units.

 

Whatever you do, know your PO2, and DON'T DIVE SOLO. Most of the CCR accidents I've read reports of have been of solo rebreather divers.... kinda stupid when you are using something which can render you unconscious without warning, if your PO2 sensors are not working that is.

 

Yeang

[Ychng 0]

Forgot to add:

 

Some good CCR models include the Prism Topaz, Megalodon, Biomarine Mk 15.5 or 16 (if you can get your hands on one), and the KISS rebreather (but high task loading on this one, since it's manually flown. no computer failures though!)

 

Other SCRs to consider aside from the dolphin:

 

Azimuth

Halcyon RB80 (probably my choice for an SCR if cost was no object) -- it's the GUE choice for deep cave penetrations

 

Things to consider before you get scared off by all the "Inspiration deaths" -- many of the deaths occurred via user stupidity (e.g. banging handset on a rock to silence an alarm, then diving), and also remember that the Inspiration has outsold any other CCR on the market by a huge margin (at least 10:1, very likely more), so by statistics one should see a much larger number of accidents given the same probability of accidents for each brand.

 

Yeang

[craig 0]

Is there really a rebreather named Megalodon? Giant, old and extinct? Sounds cool but somehow strangely undesirable!

 

Great thread, though.

[tshepherd 0]

One other note on the weight issue with the Inspiration. Pete has had a few custom metal components fabricated. For example, I believe he replaced the plastic cover with a custom fabbed metal version. The issue is that in NJ, gear takes a serious beating, especially with penetration wreck diving. The metal components give some additional protection.

 

The point of this rambling comment is that the travel weight might not be quite as bad as with Pete's.

[Ychng 0]

Craig,

 

http://www.customrebreathers.com/products.html

 

Check out the mini-Meg -- according to those who saw it at DEMA, it's small enough to fit into an overhead bin in a plane (without tanks I think).

 

Cute, like the Inspiration Evolution.

 

Yeang

[donauw 0]

If I were to go RB, I'd go CCR

 

Do any of you guys actually DIVE these things?

 

Regards,

[Ychng 0]

Not me I'd love to go for one, but training and cost of unit probably adds up to over $8.5k... lot more than a 1Ds. Most of the electronic CCRs are floating around $7-8k, training usually runs around 1k or so.

 

Not to mention that I'd have to find a dive buddy that dives a RB here in Boston, as if you dive with someone on open circuit, lots of the advantages are blown! (You do keep a lot warmer on a RB from the moist, warm air though)

 

Yeang

[tshepherd 0]

Like I said in my earlier posts, I don't, but I dive with people who do use both types. This thread has definitely gotten me thinking about getting into SCR. I can probably rent / borrow the gear to test it out, and it might be fun to try. Definitely won't be going the CCR route, it's going to be too expensive and too time consuming.

[scubag 0]

Eric,

 

Sorry I've never dove a CCR, but to a SCR the dolphin is simple, easy to set up and you'll find many livaboards and resorts that have them in rental and have sonfolime or equiv on hand. Mayby just bring your own breathing loop on a trip. It's a good place to start your training even if you eventually want to go the CCR route.

 

Doug

[martys 0]

I dove my Drager Dolphin for 3 years with 250+ dives before I got trained on an Inspiration last summer. Rebreathers are expensive, cost more to run, more to maintain, more to travel with because you will always be over your weight limit / baggage limit. I don't think the Dolphin is terribly complex to dive with (compared to my Inspiration). If you've been ceritifed for adv nitrox you've already completed half the course. The Dolphins are more readily available as rentals around the world than any other rebreather, but you need to do your research before you go. Many of the Aggressors have them. And more resorts are starting to support them. You can travel with all your cylinders and divesorb, but the hard part is getting the rich nitrox mixes you will need. Most places won't blend above 36% and you will need 40-50% depending on the diving you do and your dosage config. I dove mine at 45% pretty much all the time, but that's a custom blend that I either mixed myself (yes, I'm a certified gas blender) or had to pay extra for because it has to be done by hand with partial pressure blending.

 

I would not recommend getting certified unless you are committed to buying one and diving one regularly. Rebreathers take practice and will take you about 20-25 dives to get really comfortable with them. I hated mine when I first got certified and thought I had wasted my money, but once I got it dialed in it was a dream. It's quiet, you breath warm moist air, extended bottom time, you get the physiological advantages of breathing richer nitrox mixes but you also have the depth limitations of the same. You won't be comfortable with it unless you use it regularly. And renting them isn't cheap, up here it's about $100/day. I tried the rent it and see if you like it routine and spent almost $1000 extra had I just bought it from the beginning. Some places will include training if you buy the unit from them.

 

However, once you get used to it, you'll never go back

 

With all the overhead and hassles you need to deal with on rebreathers - I never dive open circuit anymore unless I absolutely have to.

 

As far as training goes, Tom Mount in Miami is one of the most experienced RB divers in the world and can train you on just about any rebreather ever made. Sunset House in Grand Cayman is also excellent. Erika Leigh-Haley is the former head of IANTD Canada and runs their dive shop now. I also visited Dive Tech in Grand Cayman and while I heard very good things about them, at the time I visited their RB instructor had just left so I don't know who's doing it now. In California I got certified at Scuba Schools of America with Rusty Berry (Trusty Rusty), he was very thorough and my open water dives were on a weekend livaboard in the Channel Islands.

 

Here's a very good Rebreather Article by Andrew Driver that was in Divers Magazine last year that talks about many of the rebreathers on the market today.

 

If you do decide to go rebreather, go with a good local dive store that's committed to rebreather diving. You'll need/want the support for service, supplies and consumables. And you'll want to build a relationship you trust where you can ask questions and trust the answers you get. The more you dive it the more questions will come up as your expertise increases.

 

Here's some other articles that are well worth reading. These are actually required reading for the Inspiration Class.

"What is a rebreather?" by Richard Pyle

"A Learner's Guide to Closed Circuit Rebreather Operations" by Richard Pyle

 

this one's not required but is also a great rebreather article. I would expect almost anyone who visits Wetpixel knows who Howard Hall is.

"Closed Circuit" by Howard Hall