Suppose I want to go to Bikini Atoll

[rjack321]

Between the 2 hour CCR dive and 1.5 hour OC dive, how much time do you figure was spent on the wreck as opposed to waiting for the deco timer to tick down?

Somewhat unrelated, but what kind of bailout do you carry while doing these dives on CCR?

For these runtimes, in these depths, CCR is doing about 45mins on the wreck, OC 30mins
CCR BO in this range/duration is usually 2x al80 (eg 21/35 or 18/45 trimix and EAN50%) plus O2 hung from the boat in a pinch.

If I decide to do the latter route, I suppose I will need to pick (and possibly buy) the rebreather I want to dive with right from the start as, if I'm not mistaken, the CCR training is to a significant degree type-specific.

air diluent courses /MOD1 are unit specific

 

[taimen]

air diluent courses /MOD1 are unit specific

With some agencies also MOD2 and MOD3 are unit specific. This can make crossovers pesky.

 

[jstrang]

Between the 2 hour CCR dive and 1.5 hour OC dive, how much time do you figure was spent on the wreck as opposed to waiting for the deco timer to tick down?

Truk master banked 16/40 for my trip. So 16/40 for diluent and for bailout. I also carried an 80 of 50%. On the Saratoga with pretty good visibility it was usually left near the radiation measuring station that was put on her. And was close to the mooring line.

at 1.3 I was getting an hour of bottom time on the Saratoga remember she is massive her flight deck sits at 90’ or so. It is 170’ to the sand. Average depth for most of the dives on her was 140-150’. The superstructure was at 60-90’, I should have spent more time there than going to the mooring line.

The OC guys were 30-40 minutes. They stayed shallower. There are 5 planes scattered around her. With a scooter and CCR it was possible to see them easily and not rack up too much deco. The OC guys didn’t see them all. I guess not surprising- the planes are at 170’.

 

[Barmaglot]

Thank you, this makes sense and clears up more than a few things. I'm looking at various CCR training paths though, and it's somewhat confusing, as far as requirements and progression goes.

Surprisingly, I just found out that I actually meet or exceed all the requirements for taking PADI Tec 40 CCR:

• Be a PADI Advanced Open Water Diver - duh
  
• Be a PADI Enriched Air Diver - SDI/TDI nitrox card, same thing
• Be a PADI Deep Diver or show proof of 10 dives to 30 metres/100 feet - I don't have a deep diver cert, but I have 20-ish dives to 28-31 meters
  
• Have a minimum of 30 logged dives, with at least 10 dives using EANx deeper than 18 metres/60 feet - I haven't counted them, but I've done three liveaboard trips, all on nitrox, as well as some shore-based diving with nitrox, so there's gotta be 30+ of those in my log books
  
• Be at least 18 years old - about double that
  
• Before Training Dive 5, be certified as a PADI Rescue Diver - card is in the mail, somewhere
  
• Before certification, have at least 50 logged dives - at 153 right now

And the course isn't even that expensive - Red Sea Diving College in Sharm el Sheikh has it at 700 euros, including gear rental. The catch is, of course, I'd be putting myself on the hook to purchase that specific unit either before the course, or shortly after, and looking at the marketplace forum, it seems like a used CCR is about $3500 or more, plus shipping. I'm also kind of surprised that 5 dives over 3 days is considered sufficient to turn a moderately experienced recreational OC diver into a qualified (if only at a basic level, but still, doing decompression dives) CCR tech diver.

Deep wrecks aside, I'm kind of ambivalent about CCR in general. On the one hand, as a photographer, the appeal of being able to dive without bubbles scaring away the fish is obvious, but on the other, it's just so much extra hassle. Rebreather-friendly dive centers are few and far between, and liveaboards even more so. Mixing CCR and OC divers doesn't really work - my last liveaboard, I overheard the cruise director discussing with one of the guests why they don't cater to rebreathers onboard: CCR divers need radically longer setup times before a dive which wrecks their timetable, the longer dive times don't really work with OC people in the group, and the sorb granules get everywhere no matter how careful you are. In all my, admittedly short, time diving I've only seen a CCR diver once - and anything other than single tank back-mount setup maybe a handful of times, so going away from that single tank back-mount will significantly restrict my travel options, and yet I will need to regularly dive CCR to keep up with proficiency. The travel weight also worries me - it's bad enough already with a camera rig and a set of OC gear; putting a CCR and extra regulators for bailout tanks in the mix will likely put me over 50kg of baggage.

Maybe I should take a couple days off work, get down to Sharm and try CCR on a rental unit, then make up my mind about it.

 

[MichaelMc]

Your profile mentions a jacket BC. I'd get into a BP/W and doubles soonest!!! Even if just with tiny double tanks locally at shallow depth. Or a sidemount rig, even with tiny tanks. The transition from doubles to CCR, or to sidemount CCR is likely less than from a jacket BC.

Do you have a buddy for this trip? Self reliance/solo experience seems high on the needs list.

I'd vote (sidemount) CCR, but that is just me. I'm not a CCR pilot, but the depth and remoteness argues for it.

 

[jgttrey]

The best plan is to find a good instructor and talk about your objectives. Then plan a training path that gets you there. Don't guess and go buy a bunch of stuff before doing that. You'll just waste your money.

One of the many possible paths, but one that gives some flexibility, is to do your initial technical training OC. Learn the basics about staged decompression, technical procedures, gas planning, shooting bags, holding stops, decompression theory, rigging and handling of additional bottles (which is useful even if you end up CCR because you'll have bailouts). Learn the basics. Plus, if your CCR craps out on some trip, you'll be able to salvage the trip on OC.

Agencies differ, but IANTD goes through Advanced Recreational Trimix (IIRC, 165' and no more than 15 minutes deco with one deco gas) and that crosses over to CCR -- i.e., learn it on open circuit, either backmount or sidemount and if you later buy a CCR, you don't have to repeat the class. Beyond that point, when you get into more advanced trimix, OC and CCR are two different training paths and don't cross over -- you have separate certifications for OC and CCR for normoxic and hypoxic. So, lots of folks do recreational trimix type classes OC, then decide (with a lot more perspective) whether to stay OC or go CCR for the next step. It's a natural decision point.

Self-reliant/solo is not part of that path. Not that it is a bad thing just to learn, but you're not going to be doing that kind of diving in Bikini - and you wouldn't want to even if they let you. That's a whole different thing.

Sidemount CCR is a specific tool for specific applications, like extended cave diving, but not what you are talking about. It would greatly limit your choice of units and instructors and isn't a good choice for you as a beginner. It's a popular topic at present because more manufacturers are coming out with sidemount versions, which creates a buzz among those who are interested/need them, not because it is necessarily some general advance in CCR technology.

Find a good instructor and work with them to plan a curriculum and schedule that works. You are asking the right questions, but what, specifically, you do from this point to get there is going to be dependent on finding a trusted instructor and planning it out. You're at the point of needing to have that discussion.

 

[MichaelMc]

Just to clarify, most of what I've read of deep dive trips is that people plan to do them with a qualified buddy that they know is set for that environment. Who they have dove with before. They do not just show up, get paired by the boat with an insta buddy and jump in for a 150' dive far from advanced support. You did not mention who you planned to do the actual dive with as your buddy. In that context, if you were relying on the boat pairing you up ahead of time, being a good buddy and being trained to be self reliant (solo) seems prudent. Sure, some do such depths as a mere warmup to bigger stuff, but that does not yet seem to be you.

Yes, a boat dive to view a wreck is not the strong use case for sidemount. Plus, moving from a jacket BC to trimix doubles + stage or CCR + bailout is a big step. Adding sidemount makes it larger.

 

[Barmaglot]

The best plan is to find a good instructor and talk about your objectives. Then plan a training path that gets you there. Don't guess and go buy a bunch of stuff before doing that. You'll just waste your money.

Obviously I'm not buying stuff before getting trained - I fully intend to rent the gear and get familiar with it before buying, same as I did with OC and photography.

One of the many possible paths, but one that gives some flexibility, is to do your initial technical training OC. Learn the basics about staged decompression, technical procedures, gas planning, shooting bags, holding stops, decompression theory, rigging and handling of additional bottles (which is useful even if you end up CCR because you'll have bailouts). Learn the basics. Plus, if your CCR craps out on some trip, you'll be able to salvage the trip on OC.

So you're suggesting PADI Tec40/45 or TDI AN/DP, but not PADI Tec50 or TDI ER before crossing over into CCR?

Just to clarify, most of what I've read of deep dive trips is that people plan to do them with a qualified buddy that they know is set for that environment. Who they have dove with before. They do not just show up, get paired by the boat with an insta buddy and jump in for a 150' dive far from advanced support. You did not mention who you planned to do the actual dive with as your buddy. In that context, if you were relying on the boat pairing you up ahead of time, being a good buddy and being trained to be self reliant (solo) seems prudent. Sure, some do such depths as a mere warmup to bigger stuff, but that does not yet seem to be you.

No, I don't have a regular buddy. All my dives so far have been in a guided group, or alone with a guide/spotter (every now and then, I'm a resort's only customer). I've ended up alone and separated from the group a few times - one of them at night, when I got distracted by a lizardfish and then had to swim alone through the darkness for a few minutes before I found them again; another when a DIN/yoke adapter on my tank started leaking early in the dive and the guide waved me off so I surfaced and swam back to the boat alone - and while they were a tad discomforting, it wasn't anything close to panic-inducing.

I'm fully aware that this is not something that will work on 2-hour 50m wreck penetration dives, although I freely admit to being ignorant on how they actually work, especially for someone who doesn't have a long-term partner - are they done by independent pairs, or groups guided by divemasters familiar with the area?

Regardless, an OC solo+sidemount course is on my roadmap - I was planning to do it on my last vacation, but the plan did not play out, so I did EFR+rescue instead.

Your profile mentions a jacket BC. I'd get into a BP/W and doubles soonest!!! Even if just with tiny double tanks locally at shallow depth. Or a sidemount rig, even with tiny tanks. The transition from doubles to CCR, or to sidemount CCR is likely less than from a jacket BC.

Where I travel, I've never seen any tanks except aluminium 12L (and I'm not adding tanks to my luggage, it's already heavy enough!), so if I go with a doubles setup, it will most likely be something that can convert between doubles and singles at a moment's notice. Possibly a Hollis SMS 75 - if I get that one, I can dive single backmount or double sidemount, and all I need to switch is one extra regulator. I presume that the sidemount training will transition into backmount CCR, to an extent, as, unless I'm mistaken, the bailout tanks are effectively sidemounted.

 

[RainPilot]

A new Poseidon Se7en Sport, ready to dive, will set you back 5000USD, less 20% if you aren't subject to EU VAT. To go to a full tech version will require a cylinder inversion kit, manual addition kit for the lungs and a deco-enabled battery.

SE7EN

A full bells and whistles tech version is 10k USD less the applicable VAT. That will have the M-28 computer etc (BP/W, harness, everything needed to dive out the box). These also all have the ability to use solid state sensors (which used ones may not have, its a 1000-1500 euro upgrade)

If you want to try a Poseidon in Sharm, PM me and I will refer you to someone there that can assist. I can also assist anyone that is looking to buy a Poseidon (the website options and pricing are a bit odd, its an artefact of their software)

 

[Barmaglot]

A new Poseidon Se7en Sport, ready to dive, will set you back 5000USD, less 20% if you aren't subject to EU VAT. To go to a full tech version will require a cylinder inversion kit, manual addition kit for the lungs and a deco-enabled battery.

I was actually reading about them last night, as I saw this post advertising a full kit for $3500, but then I started looking at reviews and apparently it requires proprietary sorb canisters which you can't refill? That'd be a complete deal-breaker for traveling to remote locations.