Expedition Pacific Abyss on discovery now...

teksimple

I won't speak for Rich, but certainly the total bailout the entire team carried in every scene I saw in that show was more than sufficient to get at least one diver on OC to the surface. Typical team bailout protocol is 1.5x, but I am sure that was covered in your Tmix training. The "sufficient" description with bailout is relative. As an example, when I dived solo from my boat anchored on a sea mount in heavy current 50 miles from the nearest safe harbor, bailout much in excess of that needed to avoid catastrophic DCS was more of a liability to my vitality, rather than an asset.

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deepreef

Hi Andy,

Thanks for the note! Bailout is always the most complicated part of these dives (by far). We used to try to standardize procedures, because everyone always says that's what you're supposed to do, and it sounds great in theory (muscle memory and all that). In reality, though, "standardize" seems to be less effective than "optimize", so for the past few years we don't make up a bailout plan until we get on site, assess the situation, assess the topside support, assess the specifics of each environment (currents, bathymetry, etc.). And then we pretty-much make it up through a discussion with all the relevant people before we do our first dive. Then, we oftentimes modify it over the course of an expedition, always aiming for optimization. I wouldn't necessarily recommend the "optimization" approach over the "standardization" approach for everyone -- but for our group, we feel more comfortable with custom bailout procedures for each project.

So, what we really have is a "bag of tricks" -- a series of semi-standard "partial procedures", which we can mix and match as needed. There are certain things that are common to all procedures (at least so far). One of them is that we always have enough OC gas available to allow a full open-circuit baliout for at least two divers, all the way to the surface. We also try, whenever possible, to have it set up such that those two divers can bailout completely independently of each other (i.e., with separated topside support).

Now...that does not mean we always carry all that gas on our person at all times. Usually, we're diving on drop-offs, that allow us to reliably return to stage bottles (most of the dives on the Pacific Abyss expedition). Typically, we each carry enough bottom gas to allow a leisurely ascent back to depths where it's safe to breathe air. If we don't have a live surface support boat, we'll usually leave air at ~130ft, then one or two EAN-50 at ~70ft, then at least two oxygen at ~20 ft. If we have a live (and trustworthy) surface support, we'll leave these cylinders in the boat. In that circumstance, the response to any SMB hitting the surface is to clip off and send down an air cylinder, and then a support diver jumps in the water to communicate with us. If we need more gas, or if the support diver can't get to us for some reason, then an EAN is also sent down.

Again, these are among our "bag of tricks", but not necessarily done on all dives.

I'd be happy to answer any questions, but right now it's bed time.

Aloha,
Rich

deepreef

A few more overdue replies:

Not sure, but I suspect the BBC version will be before the Discovery version. If I find out (and if I'm happier with the BBC version), then I'll post here.

Thanks!

Yeah -- we thought that was pretty funny. We'd never heard it put that way before, but we all laughed when we heard it. Anyone who has seen the complete (unedited) version of that "fish stealer" scene knows that it was all totally in good fun. We weren't thinking in those terms when it was happening (just doing our normal thing), but in retrospect, we especially like it because it captures why we do this stuff in the first place.

EXACTLY!! That states it much more concisely than I've ever said it!

I hope to be, yes.

Aloha,
Rich

deepreef

Very well stated! I agree completely! As I said, we usually aim for at least two complete bailouts (which we figure is enough -- given that we've never had even one complete bailout in all our diving). As you say, dragging too many cylinders can be a real liability (especially when currents are involved). That's part of why we prefer "optimization" over "standardization". Of course, we're not in the business of training people -- and in that context (or in the context of diving with people you don't dive with all the time), standardization is often better.

O.K., definitely time for bed....

Rich

Caves&Bunnies

Nice show,

I do have a question though. Considering the fact that you guys were in open ocean, why was the water pouring out of the electronics so dirty? It looked like the water got in on Expedition Amazon Abyss? or were you guys wrestling with a mudfish at 300 meters

Safe diving...

Cheers,

Mike

chunter

Try filling your television up with clean water and see what pours out afterward.

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Caves&Bunnies

just tried it, didn't get any dirty water, just a bunch of smoke!

silent running

Rich, thanks very much for the detailed reply. Now that you mention the staging, I thought I saw a couple of shots where you guys dropped in with more cyls than you had on the bottom. This is an interesting subject to me because, as you said, of the complications of BO planning for exploratory diving in remote places. Although my tmix training was done with standarized team BO, I do a lot of my diving with only 1 other CCR diver in remote places like PNG and Indonesia.

The dive conditions are a big factor and I agree with teksimple that in some places where there is a lot of current, carrying lots of BO is not practical and can in fact add more hazard to a dive. But then staging the BO at the top of a wall can be problematic if there is a possibility of being blown off that spot, tough call. In those situations, surface support can be crucial and you need a boat crew with good eyes and good communication skills. We had surface support for my deepest dive to date-104M-with a diver and gas ready to go if an emergency bag went up. But as you also said, one must always have enough bottom gas to get up shallow to EAN depths. Everyody's comfort level is different and since everybody must be in agreement on the plan, we must be good at optimizing to fit the particulars of the location.

With all this in mind, I'm wondering how likely you think a total loop failure is
and have you ever had one? - Andy

silent running

Yes teksimple, I did train with team BO stratagey and I agree that if you are going to do a challenging dive in heavy current, carrrying lots of BO can make things very difficult.

On my last trip to not so remote Cozumel I used a side mout rig for my BO and barely noticed a difference between the 40 I carried for some dives and the 80 I carried for others, but of course none of the dives were anywhere near as challenging as some of the diving in in PNG and Indo. Still sussing out my comfort level...

deepreef

Two words: Lithium batteries.

The battery compartments are designed to be sealed from the battery side, such that a flood of any single battery compartment won't flood the electronics (or any other battery compartment). However, a total flood of the electronics compartment (with commensurate increased positive pressure within the electronics compartment upon ascent) will cause the battery compartments to flood from the electronics side.

In fact, it was the lithium batteries that caused me to assume that the electronics were burnt toast -- and why I was so amazed to get them working again.

Oh, and I can confirm: the sequence shown on TV was, in fact, the actual moment when the electronics were first opened. I'd pretty-much deduced what had happened before I opened it, so I called the film crew over to get it on tape. It's not every day you get to see nasty brown lithium water being poured out of a Cis-Lunar MK5 main electronics housing, so I figured it was worth capturing for posterity...

Aloha,
Rich