Catastrophic Failure - How much weight to drop? Theoretical Discussion

[TSandM]

I think we can swim up more weight than we think. I know I have swum up 10 lbs; I have seen a video of a friend swimming up 25 in a pool. I'm not sure I could lift 25, but I haven't tried, and adrenaline is a wonderful thing . . . I'm sure that, in the OP's scenario, if one had ten or so pounds ditchable, the thing would be easily managed.

 

[Peter_C]

Ummm...Monterey is often 48 degrees, and a thing called a drysuit is in order, which serves two safety points. First it supplies a redundant buoyancy device, the fear of equipment failure you are discussing. Second it keeps a body from going hypothermic for much longer, in the event you wind up floating in the ocean for an extended time (Or in my case just shivering thinking about wearing a wetsuit while diving locally, and having flashbacks).

DIN is superior to yoke since it has a captured o-ring. Even if an o-ring blew on a LP hose you would still have plenty of time to make it safely to the surface before the tank completely drained.

 

[rsingler]

To all,
This is more fun than I thought for a first post!
Lots of good suggestions here, and a few replies are in order.
For simplicity's sake, I lumped embolism in with my decompression sickness "phobia", and as a doc, for those of you who haven't seen it, you might reconsider being gorked vs. being dead. Just my 2cents from an old guy. But I interject that just to keep the emotions high, lol!

Since the thread was created to discuss weight and buoyancy, let's look at some of the more recent replies.
eelnoraa hit the nail on the head: "If you ditch too little, you still won't be able to swim up. If you ditch until you can swim up, you will have uncontrolled ascent at some point." This was exactly why I raised the question. I don't think you should be dumping much weight at all. A BC failure and dumping weight at depth is a request for an embolism.
If it's a BC failure, your buddy can help you go up until you're less negatively buoyant.

If it's a first stage failure, you can start the swim up and dump air from your (previously neutral) BC.
I think that droppable weight is a solution in search of a problem, with exceptions for the shallower depths where an uncontrolled ascent won't much matter. But then again, I haven't been diving for ten years.

I agree with DIN vs. yoke for O-ring failure, but as for dry vs. wet, I'm an old guy just starting to dive Monterey to see if I really need a drysuit. Not uncommon for California newbies. So despite flots fears for my stupidity, I'm an old single tank guy being careful with proven gear for a simple dive (and yes, a 7mm full wetsuit + 5mm hooded vest requires 26-28 lb). How many folks don't have a pony? What should they be taught? Drop weight or not?

The buddy's "disappearance" for 15 sec is not an unreasonable assumption if you're suddenly without ANY air (kelp, visibility). What do you do? Hold your breath (NOT!) and look around for one minute? And that's why I asked how much to dump. As for tank buoyancy values, my recently hydro'ed old Scubapro 95 is (by the book) -4.8lb full and +0.6lb empty, without a valve.

The folks I agree with seem to suggest that getting rid of "a little" is the way to go with a first stage failure.
With a BC failure, we are maybe diverging between those (me) who want some buddy help to start the ascent, and those who will dump any weight at all. Once you dump weight, you are going to be very light in the last 33 feet if you went deep in a thick wetsuit. I don't want to embolize. rjack321's opinion nothwithstanding, if I happen to have a patent foramen ovale in my heart, I don't want to stroke out. Seen it. Of course a drysuit is the best way to go in cold water. But how many Monterey divers are in wetsuits? How many briefly go to 100 feet? It's a good theoretical discussion, whether or not its done with or without a pony. Do you want to reach for your weight belt buckle when you start to panic?

DevonDiver had a good summary of the problems inherent in dumping weight. We just disagree whether it would be better to be dead or stroked, lol! But it's an imaginary "worst case scenario" for all the reasons that SB is a great forum.

Everything gets easier at 40 feet. I asked the question because dropping weight at 40 feet might not matter much. Developing that habit, and being at 100 feet might make you miserably disabled for life. I'm trying to re-establish my muscle memory.

The whole point of imaginary worst case scenarios is to make a decision in advance. I concluded awhile back that dropping any weight in a true emergency is not first on my list. Since I'm coming back to diving, with lots of technical advances, I thought I'd ask the question again.

My conclusions:
If it's a BC failure, I need help from my buddy (rec divers only - that's another discussion).
If it's a first stage failure, I'm already neutral and I just swim up, vent BC air, exhale and hope for the best.
If it's a medical emergency, I won't drop the victim's weight, but I'll pop a little burst of air into the BC and help him/swim him up.
Reaching down with my right hand to blindly drop all my weight is something I'm going to try to erase from my muscle memory, and leave for a conscious, slower decision for special cases when DCS isn't a concern, but getting air is. You know, the run-of-the-mill stupid mistakes that at least once happen to all of us, where you might be OOA and flots will call you stupid and bring Darwin down on you.

I just think I'm going to try to remove "drop my weight belt!" from my early decision tree. Thank you all for a great thread!

RCS

 

[ozzydamo]

You are probably not going to have a Bc failure and run out of gas both at the same time. Recreational diving doesn't normally deal too well with independent, simultaneous failures. Right? So.......

Failure mod number 1: Complete loss of BC function

Response: Be able to ditch enough lead so that you can initiate an ascent by swimming up in a negatively bouyant condition. At some portion of the ascent, you will reach neutral buoyancy, which would allow you to pause your ascent, maybe rest a little and then the reaminder of your ascent would be floating up,,, i would do it in the spread eagle, (upside down skydiver position) which generates tons of drag, causes zero exertion and allows you to see the surface approaching.... Not sure exactly how much lead that is. This is the concept of a balanced rig... a rig you can swim up after ditching some lead..

You can estimate the required ditchable lead, by experimentation at depth.. empty the BC, remove the weight belt and start to remove weights until you feel like you are light enough to easily swim up... that is how much lead you would need to be able to ditch.. depends on your strength and swimming ability..If you are strong, you could ditch less lead and this would allow you to make a more controlled ascent.

Failure mod Number 2: Complete and instantaneous loss of scuba unit function, solo with no help at 100 feet. Presumably you would be neutral when this occurs...(in other words the BC is not compromised) .. Begin to swim up, which will make the diver increasingly buouyant, exhale gently, and as the ascent speed begiins to feel sufficient, stop kicking, rest and ride the bouyant ascent up. If it feels like you aren't going to make it, ditch some lead....If it is going too easy/too fast.. dump some air from the BC on the ascent.

I have had failure number 1 occur twice and number 2 never (although I have run very low on air on the bottom before).

Now if you want to be able to handle failure 1 and 2 at the same time, then you really should be considering using a redundant supply of air...like a pony bottle.

failure number 1- just swim up using ure fins as you get up you'll become neutral on the surface and you'll still have your lead weights.

failure number 2 - swim up, suckling the air from your bcd as it expands ascending using the mouthpiece and release button as you need a breath- yes! you have redundancy albeit a small amount- then chuck another tank on get back in the water and do stop at 5m to 3m for 10minutes.

1 and 2 together- won't happen unless your disgracefully bad on maintenance. dont hire gear own it and look after it!

---------- Post added February 18th, 2013 at 06:25 PM ----------

To all,
This is more fun than I thought for a first post!
Lots of good suggestions here, and a few replies are in order.
For simplicity's sake, I lumped embolism in with my decompression sickness "phobia", and as a doc, for those of you who haven't seen it, you might reconsider being gorked vs. being dead. Just my 2cents from an old guy. But I interject that just to keep the emotions high, lol!

Since the thread was created to discuss weight and buoyancy, let's look at some of the more recent replies.
eelnoraa hit the nail on the head: "If you ditch too little, you still won't be able to swim up. If you ditch until you can swim up, you will have uncontrolled ascent at some point." This was exactly why I raised the question. I don't think you should be dumping much weight at all. A BC failure and dumping weight at depth is a request for an embolism.
If it's a BC failure, your buddy can help you go up until you're less negatively buoyant.

If it's a first stage failure, you can start the swim up and dump air from your (previously neutral) BC.
I think that droppable weight is a solution in search of a problem, with exceptions for the shallower depths where an uncontrolled ascent won't much matter. But then again, I haven't been diving for ten years.

I agree with DIN vs. yoke for O-ring failure, but as for dry vs. wet, I'm an old guy just starting to dive Monterey to see if I really need a drysuit. Not uncommon for California newbies. So despite flots fears for my stupidity, I'm an old single tank guy being careful with proven gear for a simple dive (and yes, a 7mm full wetsuit + 5mm hooded vest requires 26-28 lb). How many folks don't have a pony? What should they be taught? Drop weight or not?

The buddy's "disappearance" for 15 sec is not an unreasonable assumption if you're suddenly without ANY air (kelp, visibility). What do you do? Hold your breath (NOT!) and look around for one minute? And that's why I asked how much to dump. As for tank buoyancy values, my recently hydro'ed old Scubapro 95 is (by the book) -4.8lb full and +0.6lb empty, without a valve.

The folks I agree with seem to suggest that getting rid of "a little" is the way to go with a first stage failure.
With a BC failure, we are maybe diverging between those (me) who want some buddy help to start the ascent, and those who will dump any weight at all. Once you dump weight, you are going to be very light in the last 33 feet if you went deep in a thick wetsuit. I don't want to embolize. rjack321's opinion nothwithstanding, if I happen to have a patent foramen ovale in my heart, I don't want to stroke out. Seen it. Of course a drysuit is the best way to go in cold water. But how many Monterey divers are in wetsuits? How many briefly go to 100 feet? It's a good theoretical discussion, whether or not its done with or without a pony. Do you want to reach for your weight belt buckle when you start to panic?

DevonDiver had a good summary of the problems inherent in dumping weight. We just disagree whether it would be better to be dead or stroked, lol! But it's an imaginary "worst case scenario" for all the reasons that SB is a great forum.

Everything gets easier at 40 feet. I asked the question because dropping weight at 40 feet might not matter much. Developing that habit, and being at 100 feet might make you miserably disabled for life. I'm trying to re-establish my muscle memory.

The whole point of imaginary worst case scenarios is to make a decision in advance. I concluded awhile back that dropping any weight in a true emergency is not first on my list. Since I'm coming back to diving, with lots of technical advances, I thought I'd ask the question again.

My conclusions:
If it's a BC failure, I need help from my buddy (rec divers only - that's another discussion).
If it's a first stage failure, I'm already neutral and I just swim up, vent BC air, exhale and hope for the best.
If it's a medical emergency, I won't drop the victim's weight, but I'll pop a little burst of air into the BC and help him/swim him up.
Reaching down with my right hand to blindly drop all my weight is something I'm going to try to erase from my muscle memory, and leave for a conscious, slower decision for special cases when DCS isn't a concern, but getting air is. You know, the run-of-the-mill stupid mistakes that at least once happen to all of us, where you might be OOA and flots will call you stupid and bring Darwin down on you.

I just think I'm going to try to remove "drop my weight belt!" from my early decision tree. Thank you all for a great thread!

RCS

at your age, why worry! just buy good gear and have some fun for a change! try not being so logical, its more fun!!!! live like a dog, for the moment'

Maybe you wanna do the rescue diver course?

 

[eelnoraa]

My previous post was trying to point out your rig described in the original post is not balanced. If you really need to be using such a thick wetsuit and you really plan to dive to 100 often, the solution is to first make the rig a balance rig by changing your suit to a drysuit. The key here is drysuit's buoyancy doesn't change as you descent. So you will be at most over weighted by the gas in your tank, which is 7lb. You can swim up with that easily without ditching weight at all. Once you reach surface, you ditch that weight belt so that you can stay on the surface.

 

[Rich Keller]

Catastrophic failure to me means that every piece of equipment fails at once and you are alone. I have all my weight on a belt and would not hesitate to drop it if needed. Doing it this way is fast, easy and fail-proof. As far as I am concerned fail-proof is the most important part. A side benefit to having all your weight on a belt is if you are left behind by a charter boat you can attach a line from a reel to the belt, drop the belt so it anchors you in the first place someone will come back to when looking for you.

 

[drbill]

I've only had to swim up with an "empty" tank twice (from 80 and 90 fsw) in my 50 years of diving. I never ditched the belt in either case and I wear 38# so that I'm negatively buoyant when filming on the bottom with a fully evacuated BCD. As a solo diver I do normally wear a fully redundant pony bottle but on these two occasions I did not.

However, your question is one I've been thinking about lately, although more due to the possibility of accidentally losing my weight belt with all that lead on it. It's never happened yet, but it could. I'm thinking of putting 20# in weight pockets on my BCD and 18# on my belt. Just wondering how that will alter my trim so it may take some experimentation.

 

[flots am]

Jeez, flots! I may be a brand new poster, but I've read a lot on SB in the last month. Your posts read the same in every thread!
No need to stir the pot here about "bad decisions."
What is it about "academic exercise" and "theoretical discussion" that you didn't get?
You gotta be kidding me: Darwin?

No, I just wanted to see an exchange about weight removal, buoyancy and ascent rates. And I got it. Thanks to all!

And that is the last time I will likely ever reply to flots on SB.

There's a reason. Most of the questions and screwups are the direct result of not doing stuff that you should have been taught in Open Water class, or doing stuff you should have been taught to not do in Open Water class.

You specified a configuration that was a bad idea before anybody ever got wet and then wanted opinions. Well you got mine. Sorry you didn't like it.

It's my preference to prevent as many problems as possible before entering the water.

The "Kicking Darwin in the Balls" reference was dead on and intentional. It's like asking "How many rabid weasels should I release at the picnic and what's the best way to get them back in the sack." The answer is "Don't bring a sack of rabid weasels to a picnic"

Sorry you didn't like my answer. Feel free to add me to your "ignore" list. I won't be offended in the least.

flots.

 

[DivemasterDennis]

I want to weigh in on hte original question of "ho much weight to ditch." First, i think the diver is overweighted in the first instance, as others have said. But more to the point, I think a diver should , as onlg as they are conscious, stay under control as long as possible. A controlled ascent beats and uncontrolled ascent. The nature of the emergency will dictate some tactics, but candidly, absent the need to escape a strong current, mentioned above, an uncontrolled buoyant ascent is something that I am not into using, and it can be the result of "too much too soon" ditching of weights. I invariable use wight pockets ( ditch one at a time very fast if needed, and put some weight in less accessible pockets, usually a small amount ( 4 or 6 pounds total) in back pockets for better trim. As "fun" as the it may be to "do the math" the useful points I think that are presented herein are these: 1. Be properly weighted in the first instance. 2. Use a weight arrangement that allows for ditching increments of weight if ditching is needed ( as opposed to simply having the option of "dropping the weight belt or dropping nothing." and 3. having an independent gas supply ( pony bottle) increases your options unless they are unrelated to gas depletion or equipment failure. 4. Keep your equipment in good repair, and inspect and test it regularly.
No flaming here. Just an intense desire to do as much diving the next 15years as I have the last 15 years. Then, when I hit age 75, I will dial it back a little.
Divemasterdennis

 

[xyrandomyx]

Hrm. As a few people have pointed out, if you're neutrally buoyant (ie. your BC hasn't failed), swimming up really shouldn't be an issue. At first it'd be just like swimming horizontally -- I don't know about you, but I can definitely exceed a safe ascent rate swimming horizontally. As you go up, your wetsuit and the air in your BC are going to expand, so ascending's only going to get easier (and quicker -- venting your BC would be a very good idea).

If your BC's failed, you're going to be negatively buoyant. How negative? I don't know, but I'm curious. It'd obviously depend on several factors: your exposure suit, your depth, whether you're properly weighted, etc. For me, personally, I doubt it could be more than 15 lbs (a guesstimate) -- definitely worth trying to swim up before ditching any weight.