if your drysuit has a SERIOUS flood, your're going to need to drop weight. Also - I never meant to imply dropping weight at depth.
Have you ever had to dump your weights?
- Thread starter WetSEAL
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Also - I don't understand your point about the BC failing. I certainly should be able to swim myself to the surface in that situtation, but then I'd have an issue with positive bouyancy at the surface, and would drop weights to be happily positive.
We're in the Basic Scuba Discussion. That pretty much predisposes us to single tank recreational diving. I'm not seeing a situation where I would be overweighted to the point where a failure would cause me to ditch any weight to swim to the surface. I've done everything from board shorts and a rash guard, to cold water with a drysuit and a heavy steel. I've never been so overweighted that I would have to ditch.
I don't see why that's an issue.
I agree, and I think this is the point of contention running though this thread all the way from the OP's honest attempt to come to grips with ditching weight vs. his instructor's admonition.
Here's an example (and search SB for "Wing Lift Calculator" if you want to run through the pieces yourself). If his wing/bcd fails he can't swim up easily. How much weight can he ditch safely AT DEPTH? Everyone is saying not to do it, or to do it only if your life depends on it. Why?
A big guy wearing a steel Worthington 95 (among the more negative steels), and a 7mm wetsuit, diving to 80 ft. Yeah, I know...he should be diving dry, but there are a lot of NorCal divers who just can't plunk down $800-3000 for a drysuit. So just go along with me on this one.
Backplate (-4#) and wing. -2# for regs and fittings. -16# of lead on belt or integrated and/or fixed. -3# empty tank buoyancy. -7.5# carried air. Total negative -32.5# not including a slight negative for a big guy with low body fat.
His nice new soft 7mm gives him estimated 26.5# buoyancy at the surface for his body surface area. So he's about 6# negative at the surface at the start of his dive with full tanks. But at the end of the dive with 500 psi, he's 0.3# positive at the surface. In other words, perfectly weighted.
But at 80 ft when his wing fails, his wetsuit is compressed and only providing 8# lift. So he's between 24-27# negatively buoyant with full tanks.
If he drops more than 6# (his initial negative buoyancy), he will potentially have a runaway ascent as his suit expands on the way up, because he will surface with positive buoyancy. If he drops exactly 6#, he will arrive at the surface neutral. But he still has to swim up ~20# at the beginning, until suit expansion helps.
This all changes during the dive due to air weight consumption.
At the end of the dive, with min air for a no stop ascent, he would be about 18.5# negative at 80 feet. With a failed wing, he would surface (whatever way he managed to ascend) 0.3# positive due to wetsuit expansion. So ditching ANY weight might result in a runaway ascent.
So there's the spectrum, and the difficulty in knowing what to do when. Despite being perfectly weighted, with a catastrophic failure and no buddy, he'd be swimming up between 18.5 and 27 lb without ditching weight, if he could do it.
With wetsuit diving, it's not a matter of ditching weight to make yourself neutral on the bottom and then swimming up, because suit expansion will make for a runaway ascent.
But by the numbers, he could ditch between 6# and 0# depending upon where he was with tank contents, and surface neutral assuming he could get himself off the bottom while 18# negative. Any more weight ditched, and at some point positive buoyancy takes over and he's no longer in control.
Those are the numbers, but just...for this guy, this tank, this depth, this wetsuit, and when exactly during the dive?...It's a lot to process.
The easy answer for safely ditching weight at depth (when wearing a wetsuit), is that you can always ditch the weight (above reserve) of the air you are carrying, without becoming positively buoyant, if you are properly weighted. For example, an AL80 holds ~6#. One pound is reserve (500 psi). Therefore, you can ditch 5# at depth at the beginning of the dive, and 2'5# at 1875. That's not much help, but there it is.
CT-Rich
Contributor
Here is the thi
But being a basic forum, best practices would assume a new diver, even with your expertly balanced rig, might want to relax and wait for rescue or do the long swim without the burden of extra lead.
The idea of ditchable weight does not encourage over weighting or being out of trim or that the solution to every problem is an uncontrollable ascent. It just means you have that tool in your bag of possible solutions.
Here is the thing, until you crawl onto a beach or a boat, you are selfcontained. Most weight ditching is going to occur on the surface, not at depth. You get to the surface and you have a long surface swim against the current, the surface conditions have deteriorated, the boat anchor dragged, you were blown off the wreck and you are waiting for a pick-up. Lots of stuff can happen where the extra lead becomes a problem. Your life may not be in immediate danger, but as stressors build up, you want to become more buoyant and reduce fatigue and anxiety. Yes, I am sure you never stress and you never get tired...
But being a basic forum, best practices would assume a new diver, even with your expertly balanced rig, might want to relax and wait for rescue or do the long swim without the burden of extra lead.
The idea of ditchable weight does not encourage over weighting or being out of trim or that the solution to every problem is an uncontrollable ascent. It just means you have that tool in your bag of possible solutions.
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In 56 years of diving, I don't remember a single time I've ditched my weights (but then I'm an old geezer whose memory may be flawed. I do remember two dives where ditching them might have been a good choice though.
I've considered splitting my weights with most on my weight belt and perhaps 10# of ditchable weight in pockets.
I've considered splitting my weights with most on my weight belt and perhaps 10# of ditchable weight in pockets.
Bob DBF
Contributor
Personally, I would find another instructor, if for no other reason than his lack of imagination.
I have dropped a belt twice, the first was before the BC and may not have been absolutely necessary. The second was freediving and saved my life. I retrieved both belts.
There have been a number of times that dropping a belt was factored into an emergency plan, but other means were found to solve the problem before it was necessary. Had the other means not worked, the belt would have been dropped.
Dropping a weight belt is a tool, it only changes your buoyancy, there are side effects, and one has to weigh their options. Once one panics there are no options, and one won't think to drop their belt, even if it is the only thing that might save their life. Telling someone not to drop their belt under any condition, making the practice thereof unnecessary, is withholding a procedure that may save ones life.
I perfer an instructor that discusses emergencies and how to appropriately react to them using any tool or procedure available in a disciplined manner. Training by catch phrase is fast, however it is not through.
Bob
johndiver999
Contributor
I'm with you on a lot of what you said, however, you are making an assumption that I do not think is correct. It is basically that ditching any more lead (on the bottom - with the thick wetsuit scenario) than is required to make the diver neutral at the surface will (or "may") necessarily cause a "runaway buoyant ascent".
A decent diver can manage excess unwanted buoyancy, even a basic diver knows that reducing their lung volume will make a big difference. So for example, if a diver drops enough lead (on the bottom) to make them 8 lbs positive on the surface, this is not necessarily gonna be a runaway situation. The diver can swim up in a negative condition and then simply stop at the depth that they reach neutral; in this example maybe 20 or 30 feet. The diver can take their time after the exertion of swimming up excess weight and rest while in a perfectly neutral buoyant condition. They would basically be doing a deeper safety stop.
When the diver is fully rested and calm, he can then start the remainder of the ascent. If there is a rock to pick up or a rope to hold, then the ascent is no big deal at all. If it is in open water, then they just need to go slow, inhale just a little bit and flair out. It is not difficult.
It surprises me that people often accept the idea that a diver can kick up 15 or 20 lbs of negative weight and not over exert themselves and manage a controlled ascent from deep water, and then still believe that managing a much smaller buoyancy "problem" - on the positive side of the equation - for just 30 feet or so of the ascent, is necessarily going to be unmanageable.
Even though excess negative buoyancy is easier to manage than excess positive buoyancy, I just can't buy into the idea that being a little buoyant is a huge problem - especially when we are talking about a last ditch, get out of Dodge, emergency escape situation. The important thing is to be able to ditch enough lead to allow yourself to swim up, if the last 20 feet is a "little fast".. oh well - maybe next time you will have some redundant buoyancy device on the dive that negates the need to drop lead on the bottom.
Haven't any of you kicked you butt off to get down, thinking it is just some extra air in the BC and then on the ascent realize that the reason it was so hard to get started was because you forgot a weightbelt (or you were way underweighted)?
Stopping and chilling at the neutral point of the ascent should be in the diver's "bag of tricks" - even if it is just needed to deal with the ACCIDENTAL loss of ballast at depth.
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This! +1!
I agree with you 100%. It's the Beginner's Forum, and I was almost out of line going into this much detail. Shifting from a need to get positive, to a need to stop at neutral, or get negative by swimming down, is a lot to think about.
Any circumstance that has you contemplating ditching weight at depth, short of an emergency buoyant ascent, should be a signal to
Stop
Breathe
Think
Act
But you know that.
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Eric Sedletzky
Contributor
Maybe for very calculated tech dives or cave dives, or some other such thing having all lead stashed away and non ditchable works out. But there are many different dive situations, styles, potential hazards, etc. so trying to say that nobody will ever not need to dump lead on the bottom or on the surface in every diving scenario around the world is not true.
Where I dive many or most people use wetsuits and steel tanks. Most who dive plates also use weightbelts. Of those divers I’ll bet 100% of them would not be opposed to dumping their belts at depth to save their life for whatever reason they deem as life threatening, be it a shark attack, other severe injury like a broken leg, blown wing in combination with severe injury, catastrophic reg system failure with no pony and MIA buddy (happens), 1000 lb bull stellar sea lion wanting to have sex with you, or whatever?
If you need to leave in a hurry and life is more important than death then dumping weight is what you do.
And suits don’t cause runaway missle ascents, overinflated or auto inflating wings do and so do overinflated drysuits that can’t be vented quick enough. Wetsuits give you a slower managable steady ascent.
Where I dive many or most people use wetsuits and steel tanks. Most who dive plates also use weightbelts. Of those divers I’ll bet 100% of them would not be opposed to dumping their belts at depth to save their life for whatever reason they deem as life threatening, be it a shark attack, other severe injury like a broken leg, blown wing in combination with severe injury, catastrophic reg system failure with no pony and MIA buddy (happens), 1000 lb bull stellar sea lion wanting to have sex with you, or whatever?
If you need to leave in a hurry and life is more important than death then dumping weight is what you do.
And suits don’t cause runaway missle ascents, overinflated or auto inflating wings do and so do overinflated drysuits that can’t be vented quick enough. Wetsuits give you a slower managable steady ascent.
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