BCD failure at 100 feet

[DCBC]

...You are making a statement that being properly weighted is judge by your ability to swim up from depth without your BCD. Those are 2 different subjects, both important concepts but different.

Buoyancy isn't brain science. Chances are if the Diver can't ascend under on his own steam from 100 FSW, he's over weighted or has forgotten to wear his fins. There are just not that many factors that affect buoyancy that are not quantified before hand. His trim/buoyancy should be a known quantity and adjustments made before he even gets into the water.

 

[dumpsterDiver]

Define thick suit.

I currently dive a tri-lam with heavy underwear but prior to this I dove a 7mm crushed neoprene drysuit and the combination of my lung capacity and maintaining a constant suit volume worked just fine with that as well.

The average set of lungs is ~6 litres so you can effectively shift your bouyancy by +-4.5 lbs by controlling your breathing which is more then enough to compensate for a crushed neoprene suit allowing for the extra weight you carry for the first 30'.

---------- Post added August 9th, 2013 at 12:02 PM ----------

PS. I also routinely dove a 7mm + 7mm wetsuit prior to the drysuits and have no problem swimming to the surface with an empty wing. If you can't swim off the bottom without the wing you're over weighted.

I define a thick suit as 7 mm maybe with an added 3 mm vest, 7 mm mitts and two 5 mm hoods.... I used to dive in maine like that. For freediving I would wear about 24-26 lbs of lead. When I would scuba with an aluminum tank, I had 4 lbs added to my BC. I was NOT over weighted. When I dove past 60 feet (on scuba) my sea quest BC would sometimes be completely full and burping, certainly on the initial part of the ascent. I think it was rated as 35 lbs capacity.

I get so tired of people not understanding suit compression and spouting off nonsense on this forum about being over weighted and also a balanced rig. a Balanced rig is NOT one you can swim up (with no air in BC) it IS one you can swim up with no air in BC after dropping whatever ballast you are willing to drop. That is my definition anyway.

 

[GrumpyOldGuy]

Buoyancy isn't brain science. Chances are if the Diver can't ascend under on his own steam from 100 FSW, he's over weighted or has forgotten to wear his fins. There are just not that many factors that affect buoyancy that are not quantified before hand. His trim/buoyancy should be a known quantity and adjustments made before he even gets into the water.

Now you are hedging a bit with "chances are".

My definition of being properly weighted is "neutral with no air in bcd at 15' with 500psi". Pretty simple, PADI OW stuff, obviously I did not invent it. It is objective and measurable and SIMPLE.

I agree, if a diver can't swim up his rig with a failed BCD, the configuration needs to be tweaked, but there are multiple ways to do that and multiple reasons why he/she might not be able to do so, over weighting is one reason, certainly not the only one.

So what's your definition of "properly weighted"?

 

[flots am]

I get so tired of people not understanding suit compression and spouting off nonsense on this forum about being over weighted and also a balanced rig. a Balanced rig is NOT one you can swim up (with no air in BC) it IS one you can swim up with no air in BC after dropping whatever ballast you are willing to drop. That is my definition anyway.

That's why I like a weight harness and soft weights for my drysuit.

If I lose buoyancy in both the BC and the drysuit for some reason (underwater knife fight?) , it's not a choice between ditching 30 pounds or nothing, I can pull open the velcro and drop a 2 or a 3 or a 5 and see what happens, Not enough? Drop another few.

Ditching it all while wearing a lot of exposure protection wouldn't give me a "warm fuzzy" feeling.

flots.

 

[openmindOW]

a Balanced rig is NOT one you can swim up (with no air in BC) it IS one you can swim up with no air in BC after dropping whatever ballast you are willing to drop.

In you definition, you mean dropping SOME weight, correct? But not all of it, correct?

 

[divealaska]

Goodness! Search the forum for "balanced rig".

 

[DCBC]

...Given this, you obviously will be negative at 100' without compensation I agree, if a diver can't swim up his rig with a failed BCD, the configuration needs to be tweaked, but there are multiple ways to do that and multiple reasons why he/she might not be able to do so, over weighting is one reason, certainly not the only one.

I've done lots of dives over 100 FSW with no BC or flotation device at all. It required me to kick. That was the only way to the surface. Before the BC, thousands of dives have been done in this manner. Divers today often load-up with reels, lights, cameras and other equipment and not consider the affect this has on their buoyancy. They feel it's OK or it goes unnoticed because they just push a button and it's looked after; well not if the BC malfunctions...

In the real world, if a diver is so negative at 100 FSW that he can't swim to the surface, he's overweighted. What other reasons are there? Catastrophic dry-suit flooding? Carrying an anchor? You're overweighted! He needs to dump weight or use redundant buoyancy. The diver knows that this is a possibility before he gets into the water. Planning, planning planning...

It's wise to have different weighting systems where you can dump one quickly to control your descent in the case of an emergency. Wearing proper fins, keeping in-shape, planning your dive well, diving with a competent Buddy and keeping a positive attitude (to prevent panic) will reduce the risk in case of a malfunction. Don't dive passively; be prepared to react. With depth comes narcosis; after a while it can be too late...

 

[Ricardo Pedraza Guido]

Completely agree!

 

[divealaska]

[/QUOTE] I get so tired of people not understanding suit compression and spouting off nonsense on this forum about being over weighted and also a balanced rig. a Balanced rig is NOT one you can swim up (with no air in BC) it IS one you can swim up with no air in BC after dropping whatever ballast you are willing to drop. That is my definition anyway.[/QUOTE]

I may be one who doesn't understand your definition of a balanced rig. By definition, if you "balance" your rig, then add "ditch-able" weight, haven't you just unbalanced it? A balanced rig is defined at two points in the dive, the beginning while at depth with full tank(s) and at the end when at your final stop with nearly empty tank(s). From depth being able to swim up WITHOUT DITCHING WEIGHT. And at the end by being able to still hold a safety (deco) stop. The balance refers to combining negatively buoyant equipment components with positively buoyant gear to result in a balance of the two. Heavy steel tanks with a thick wetsuit is a very difficult (if not impossible) combination to balance. With an unbalance rig, if a diver were forced to ditch weight at the end of the dive (when he is most likely to run out of air) he would not be able to complete a safety (deco) stop. If he could, the weight was unnecessary to begin with. Wet suit compression is precisely what CAUSES imbalance.

 

[GrumpyOldGuy]

I've done lots of dives over 100 FSW with no BC or flotation device at all. It required me to kick. That was the only way to the surface. Before the BC, thousands of dives have been done in this manner. Divers today often load-up with reels, lights, cameras and other equipment and not consider the affect this has on their buoyancy. They feel it's OK or it goes unnoticed because they just push a button and it's looked after; well not if the BC malfunctions...

In the real world, if a diver is so negative at 100 FSW that he can't swim to the surface, he's overweighted. What other reasons are there? Catastrophic dry-suit flooding? Carrying an anchor? You're overweighted! He needs to dump weight or use redundant buoyancy. The diver knows that this is a possibility before he gets into the water. Planning, planning planning...

It's wise to have different weighting systems where you can dump one quickly to control your descent in the case of an emergency. Wearing proper fins, keeping in-shape, planning your dive well, diving with a competent Buddy and keeping a positive attitude (to prevent panic) will reduce the risk in case of a malfunction. Don't dive passively; be prepared to react. With depth comes narcosis; after a while it can be too late...

You do realize we are saying the same thing but using different terminology? We are arguing semantics, you are merely adding the ability to swim up your rig to the criteria for being "properly weighted". I consider it a separate but equally important issue.