One more near-miss

[Charlie99]

Plongeursousmarin, could you please clarify a couple of things?

In the original post, it sounds like you turned the dive solely because of time. What sort of air pressure turnaround, if any did you have (either personal or agreed upon by the group)? Did you adjust that turnpoint to reflect the gas you used fighting the current on the surface? And take into account that you would be fighting a current back to the upline?

I wonder if the "separation" of buddies was simply the first diver calling the dive, but not getting acknowledgement from you and his buddy.

It sounds like one of the aggravating factors was the current, which caused you to both use more gas and use more time getting back to the upline that you intended.

While some posters don't like the "tech overtones" in the various posts, recreational divers would be wise to add some of the technical dive planning techniques to their skillsets. In particular, gas management.

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Thanks for posting about your dive. Hopefully it will help me in my ongoing struggle to keep make myself more willing to abort a dive when unexpected events or conditions start the dive down the road towards disaster. Like a lot of divers, my first instincts are to just keep plugging away, rather than analyzing the worsening situation and taking remedial action such as ending the dive early.

Charlie Allen

 

[plongeursousmarin]

Plongeursousmarin, could you please clarify a couple of things?

In the original post, it sounds like you turned the dive solely because of time. What sort of air pressure turnaround, if any did you have (either personal or agreed upon by the group)? Did you adjust that turnpoint to reflect the gas you used fighting the current on the surface? And take into account that you would be fighting a current back to the upline?

I wonder if the "separation" of buddies was simply the first diver calling the dive, but not getting acknowledgement from you and his buddy.

It sounds like one of the aggravating factors was the current, which caused you to both use more gas and use more time getting back to the upline that you intended.

While some posters don't like the "tech overtones" in the various posts, recreational divers would be wise to add some of the technical dive planning techniques to their skillsets. In particular, gas management.

---------------

Thanks for posting about your dive. Hopefully it will help me in my ongoing struggle to keep make myself more willing to abort a dive when unexpected events or conditions start the dive down the road towards disaster. Like a lot of divers, my first instincts are to just keep plugging away, rather than analyzing the worsening situation and taking remedial action such as ending the dive early.

Charlie Allen

Hi Charlie,
I remember that upon exiting the wreck just under the wheelhouse to make my way towards the line, I had about 800 psi or so and three minutes of decompression on the computer but then I got out "in the open" as I had to go past the wheel house to get to the line with nothing sheltering me from the current. I basically had to make a big swimming effort against the current, burned a ton of gas as I did not want to get back down at that point to use the wreck's deck to shelter myself, as I would have been about 20 feet below where I was currently. I knew I was not "diving at my best" at that point but I figured I'd be OK once coming up, even with 500 psi. I figured I wouldn't have a whole lot left in the tank once back on the boat but I believed that I'd be able to do the deco stop (which at that point was 5 minutes). I had no idea where the other two guys were, for all I knew they'd already made their way up. It's only when I got on the line and started my ascent that I saw the one guy that I eventually assisted in his OOA situation.

 

[cummings66]

103 ft with 800 psi in a 80 sized tank is not much air in case of an OOA situation as you found out. You guys were lucky it was shallow when the other guy went OOA and not deep or you would have been in deep... Having a deco obligation and not enough air to handle it is very dangerous.

Like the conversation I had with my new dive buddy went, I'll tell you in shorter form without the math. We'll plan a dive based on coming up with an OOA diver, whatever number of cubic feet we decide is needed to support both of us and do our safety stop, that air is not to be used on the bottom. We can use that air if it's available and we're at a shallower depth because the amount of air needed for the emergency is less at say 30 feet than it is at 100 feet. Just because we leave the bottom with 1400 psi in your tank doesn't mean you'll have 1000 psi in your tank when we surface.

On that briefing when we got to 30 cf of air in his tank the dive was turned, it was not his air to freely use as he saw fit. If he breathed it he's using some of my air and vice versa.

I highly suggest looking for a post from Lamont and taking to heart the air management lessons he's got at the bottom sig line. It may save your life and your buddies.

This is not in the realm of technical diving, it's dive planning and what we all should do.

 

[IceIce]

I agree with the other posts - 80 cu ft is not enough gas for a dive >100 fsw, particularly on Nitrox. I now dive a steel 119, and I bring them with me instead of renting.

I'm still learning and always, so correct me if I'm wrong.
I have dived with AL80 to more than 100 ft wreck or 130 ft reef before, it's common and I see nothing wrong with it, if you manage your air consumption.
Anyway, for most of the dive, we did multilevel dive, we didn't stay at those depth the whole time but gradually we moved shallower and shallower until we did the safety stop in the reef, sometimes without us realising that we had done the safety stop by enjoying the view at 3-5 meter depth.
Since we consume more air on depth, on air, AL80, non-deco dive, what you should do is pay close attention to your SPG and dive-com, and not to exceed the non-deco time, calculate the depth to give you enough air to move shallow, complete the safety stop and emergency air.
Many of my above dive still able to give me 60 minutes bottom time with AL80, with around 50 bar left, but of course, I don't have the luxury to explore the depth and the wreck as much as I want, but that's what I can do with my current training.

If the situation is not what you expect to be, like strong current, choppy surface, drop visibility, cut short some percentage of the dive and give luxurious air to surface, for backup in case you need it.

Plongeursousmarin, thanks for sharing your experience. I think you did good that you still tried to help your buddy when you are almost OOA yourself. What you missed is the gas management, but I'm quite sure that you live to be a better diver. You took the first step by admitting what you did wrong, the rest depends on you.

 

[DandyDon]

IMO, 80 cf is not big enough for the deeper dives - it's just that the industry has adopted them as standard. 120 would be a lot more reasonable.

ilot: I can't fly a tank on trips, tho - so I do what I can. I try to rent larger tanks, and I always have a 19 cf pony on deeper dives, just in case - altho it's never part of the plan.

 

[jeckyll]

Don: I run up against NDL time with an AL80 before going beyond rock bottom.

On a recent dive to 100 fsw we spent 17 minutes below 90 fsw before working our way up the line. With stops at 1/2 depth, 40, 30, 20 and 10 the dive was over 30 minutes and I came out with 800 psi, my buddy with over 1000. We left the bottom with over 1500 psi.

I think a Al80 is plenty large to get you there and back, though I do sling a 40 (not part of the gas plan).

Just having a larger tank for someone who's not paying attention to their bottom time, gas remaining or the location of their buddies is not the solution IMO. Especially when they are willing to bend their computer and head back in...

But then, what do I know

Bjorn

 

[ERIC.K]

I'm up for having larger tanks and more breathing gas, At the Duane if I was offered a larger tank of course I would take it however this blanket label about having larger tanks for dives deeper that 100fsw kinda unreasonable. The rec diving limit is 130feet right, it doesn't say the limit is 100 feet on standard alum 80s and 130 if you have
120s, I can see where conditions would exist that having a larger tank would be helpful, especially in the situation that started this thread. If people started having OOA situations and deaths at the Duane (I know there have been a few) but would'nt the most paranid about lawsuits, The dive operators start using larger tanks to ward off potential lawsuits?

 

[Puffer Fish]

I'm up for having larger tanks and more breathing gas, At the Duane if I was offered a larger tank of course I would take it however this blanket label about having larger tanks for dives deeper that 100fsw kinda unreasonable. The rec diving limit is 130feet right, it doesn't say the limit is 100 feet on standard alum 80s and 130 if you have
120s, I can see where conditions would exist that having a larger tank would be helpful, especially in the situation that started this thread. If people started having OOA situations and deaths at the Duane (I know there have been a few) but would'nt the most paranid about lawsuits, The dive operators start using larger tanks to ward off potential lawsuits?

I believe your point is important. The problem was never the size of the tank, but gas management. Larger tanks on everyone, with the same management and the situation would have been far worse..

 

[MikeFerrara]

I'm up for having larger tanks and more breathing gas, At the Duane if I was offered a larger tank of course I would take it however this blanket label about having larger tanks for dives deeper that 100fsw kinda unreasonable. The rec diving limit is 130feet right, it doesn't say the limit is 100 feet on standard alum 80s and 130 if you have
120s, I can see where conditions would exist that having a larger tank would be helpful, especially in the situation that started this thread. If people started having OOA situations and deaths at the Duane (I know there have been a few) but would'nt the most paranid about lawsuits, The dive operators start using larger tanks to ward off potential lawsuits?

A couple of points.

130 ft is the the depth that most agencies commonly recommend and a maximum for recreational no-stop diving. They don't say anything at all about what size tank you should have. In fact, most agencies don't even teach gas management. Just because someone hands you an al80 for your open water class doesn't mean that it's the best tank for all recreational diving.

Personally, I limit my single tank, single output valve diving to real shallow stuff. If I'm going very deep at all I want some redundancy. That means a single with an h-valve at the least or my doubles.

Since the volume of gas I carry limits my bottom time and the time I have available for handling problems, I don't bother with deep dives on little single tanks. Of course, I don't bother trying to plan dives over 100 ft as no-stop dives either. Aside from the slim margines, spending good money on charter fees for what amounts to a little bounce dive just doesn't seem like the way to go.


How I prefer to do a 130 ft wreck dive...
I'd opt for my doubles, a light trimix, one decompression gas and I'd plan on 30 minutes or so bottom time. Run time would be right about 60 minutes...a more than reasonable run time in OW. The doubles provide redundancy and I would have plenty of gas and plenty of time so there's no pressure. A light trimix at those depths (an END of 70 or 80 ft) makes for a real comfortable dive. Using a decompression gas keeps decompression short and in the case of an air share situation lets divers get back on their own gas near the surface where conditions might be a little rough...and I'd be in good shape for doing a second dive on the way in without even having to change out tanks.

I've done dives like this other ways but, this, or some reasonably close aprox of it, is the way to go for me.

 

[MikeFerrara]

IMO, 80 cf is not big enough for the deeper dives - it's just that the industry has adopted them as standard. 120 would be a lot more reasonable.

ilot: I can't fly a tank on trips, tho - so I do what I can. I try to rent larger tanks, and I always have a 19 cf pony on deeper dives, just in case - altho it's never part of the plan.

I try not to fly at all but...just pick an oporator that's doing dives that are appropriate for the available equipment.

Increasingly there are more "tech" oriented charters all over the place so getting bigger tanks of even doubles shouldn't be that hard in most areas.

Additionally, the "tech" charters usually don't seem any more expensive and when you consider the bottom time, I think they can be more economical even if they were a little more money...and you probably avoid the fire drill of being around when a bunch of single tank divers come scrambling up the line about out of gas.

The way some of these outfits are doing some of these dives, I wouldn't even want to be in the area let alone in the water.