Wing size for 5mm wetsuit aluminum 80

[decompression]

I had an interesting experience relative to this thread the day before yesterday.

One of my students had accumulated a pretty fair number of dives with his dry suit and his BP/W over the course of the training, and he was doing pretty well. On Monday he decided to wear another layer of undergarment on his upper body because he had been cold the day before. (I did not know he did this.) As the dive progressed, he realized he was underweighted. He dumped everything he could from his wing and his suit, but he was still about to cork. When he let me know the problem, we began an immediate ascent. He hung onto me for much of the time we were doing our deco stops, and I was fortunately weighted enough to keep the two of us down. He also was able to cling to the rocky wall hear us for some of the stops.

He added more weight for the ensuing dive and was fine. He had not realized how close he was to his weighting before, and he had not realized how much difference that extra shirt would make.

It is fortunate for him I was able to keep him down when he first realized his problem. If he had corked right away and missed his decompression stops, it could have been serious. A friend of mine, a very experienced technical diving instructor, corked on a dive that way, missing his deco stops. He was able to get on oxygen right away, which helped him enough that he was only paralyzed for about 5 months.

You'd think he would have noticed the difference when he had difficulties descending, or at least not needed to add air to the wing at depth. Good thing you were overweighted enough to stop him from corking.



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[boulderjohn]

You'd think he would have noticed the difference when he had difficulties descending, or at least not needed to add air to the wing at depth. Good thing you were overweighted enough to stop him from corking.

It was a technical dive, so the weight of the gas lost during the dive was enough to allow him to descend. In addition, he was carrying two deco cylinders on descent, and we staged them early in the dive. When he let me know he was in trouble, I took him back to the deco cylinders, and those helped. Of course, as they lost their gas, he was in trouble again.

 

[OldNSalty]

In the world of underweight / overweight the answer is to be correctly weighted and have enough lift.

 

[decompression]

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[boulderjohn]

I don't think we are talking about sitting like a slug on the bottom in this thread.

 

[cool_hardware52]

I had an interesting experience relative to this thread the day before yesterday.

One of my students had accumulated a pretty fair number of dives with his dry suit and his BP/W over the course of the training, and he was doing pretty well. On Monday he decided to wear another layer of undergarment on his upper body because he had been cold the day before. (I did not know he did this.) As the dive progressed, he realized he was underweighted. He dumped everything he could from his wing and his suit, but he was still about to cork. When he let me know the problem, we began an immediate ascent. He hung onto me for much of the time we were doing our deco stops, and I was fortunately weighted enough to keep the two of us down. He also was able to cling to the rocky wall hear us for some of the stops.

He added more weight for the ensuing dive and was fine. He had not realized how close he was to his weighting before, and he had not realized how much difference that extra shirt would make.

It is fortunate for him I was able to keep him down when he first realized his problem. If he had corked right away and missed his decompression stops, it could have been serious. A friend of mine, a very experienced technical diving instructor, corked on a dive that way, missing his deco stops. He was able to get on oxygen right away, which helped him enough that he was only paralyzed for about 5 months.

What part of the OP's post concerning single tanks and single wings leads you to believe he is intending dives with mandatory decompression?

As you well know it's a very different animal. The physics of buoyancy and lift remain the same, but the assumptions change. The risks with an inability to hold deco stops, and perhaps in particular shallow stops for staged decompression dives is not *vanishingly small* and my weighting recommendations, and how a diver chooses to carry their ballast changes for tech diving.

None of which pertains at all to the question asked by the OP.


Tobin

 

[dumpsterDiver]

Some might argue OJ was innocent too.

Can you produce for me a *single* scuba accident report where under weighting was cited as a cause or contributing factor?

Tobin

You think that weighting or loss of control of buoyancy is not associated with dive accidents? Seriously?

The whole idea of proper weighting is to be ale to be in total control at ANY time in the dive (and still be able to breath normally/comfortably). In other words NOT be floating uncontrollably to the surface from a shallow depth.

I've argued that it is nice to 4-5 lbs negative at the safety stop so you can hang on a string and keep an SMB somewhat vertical. The context of the discussion was a 5 mm wetsuit. One individual has indicated that a significant loss of buoyancy occurs at just 15 ft (30%). I have nothing but anecdotal information to support this claim, but it seems reasonable to me.

So... a diver who is wearing a wetsuit, is going to be VERY minimally "over weighted" in order to hang from an SMB when the suit is compressed AND be able to remain negative or neutral as they approach the surface.

As Boulder John described, having some excess ballast saved the day. If presented with that kind of situation, I would encourage the diver to find a suitable rock and carry it to the surface. This technique might be a useful idea should a diver accidentally lose ballast that is not recoverable on a dive or.. as I have seen happen...a diver hauls themselves down an anchor line in a strong current and rough seas and the conditions are so challenging that they might not notice they forgot a weightbelt on the boat.

The ability to have excess negative weight is similar to my personal preference to use a BC which has more than the absolute minimum level of lift for me. Having excess capacity to assist a diver (say with a failed Bc) is something that makes me feel comfortable. If I were diving solo, in warm water with a smaller tank, I could probably do fine with no BC, but if I am diving with a buddy, I feel it would be irresponsible to not have the extra capacity to help/rescue a diver who gets themselves in trouble.

 

[cool_hardware52]

You think that weighting or loss of control of buoyancy is not associated with dive accidents? Seriously?

1) Loss of buoyancy control is perhaps even more likely in the over weighted diver.

I've not *once* said anything about loss of buoyancy control not being a factor in dive accidents.

Not once, not ever.

I'll note in a current thread here on scuba board I proffered that good buoyancy control is a sign of a good diver.

To suggest that I have claimed loss of buoyancy control is not associated with dive accidents is dishonest. Stop putting words in my mouth.

2) Show me the accident reports for recreational scuba divers that include insufficient ballast as a contributing factor.

Tobin

 

[dumpsterDiver]

1) Loss of buoyancy control is perhaps even more likely in the over weighted diver.

I've not *once* said anything about loss of buoyancy control not being a factor in dive accidents.

Not once, not ever.

I'll note in a current thread here on scuba board I proffered that good buoyancy control is a sign of a good diver.

To suggest that I have claimed loss of buoyancy control is not associated with dive accidents is dishonest. Stop putting words in my mouth.

2) Show me the accident reports for recreational scuba divers that include insufficient ballast as a contributing factor.

Tobin

Having insufficient ballast to control your position is, by definition, "a loss of buoyancy control".

Are you back peddling on your assertion that divers should dive with so little ballast that they can not stop their ascent at any depth they wish?

 

[halocline]

You think that weighting or loss of control of buoyancy is not associated with dive accidents? Seriously?

I think most experienced divers know that loss of buoyancy control is associated with dive accidents, Tobin included. But I don't think that has anything to do with this thread. With regards to weighting and dive accidents, I strongly suspect that a common reason for uncontrolled ascents is unintended weight dropping, like a quick release pocket that falls off the BC. This problem would only be made worse by starting a dive with excess ballast and then diving with excess air in the BC. It has nothing to do with being underweighted at the beginning of a dive.

Technical divers with hard ceilings, very different scenario. And IMO anyone doing serious deco diving that cannot weight themselves correctly probably ought to reconsider deco diving.