losing weights / uncontrolled ascent

[justbillin]

Update…I actually lost one of my Transpac weight pouches on a recent diving trip to South Florida. While diving the Captain Dan in Pompano I noticed my right weight pouch just hanging by the clip. I fixed it underwater and it happened a second time later in the dive and I fixed it again. Several days later while diving on the Vandenberg in Key West I noticed I no longer had my right pocket. I assume it must have popped out and I lost it on the wreck. I only had 3 lbs in each pocket, and I did notice that I was a little "floaty" while coming up the ascent line with my wing drained of air. The current was really ripping that day, and I imagine it was strong enough to detach it from the clip if it was dangling. I did attach my reel to the right waist D-ring, and I suspect that my arm or the weight of my Manta Jr reel might have put enough pressure to push the weight pouch out of the pocket. A single 3 pound hard weight kind of hangs out of the pocket a little from gravity while diving, and pushing on it may possibly cause it to pop out in my opinion.

 

[drbill]

Diving with just 10 lbs of weight really limits your options a bit (but congratulations). Seems the "only" thing you can do is to insure that the weight pockets are secured. If they were just velcro I'd be worried but with velcro AND a clip you have more security. I dive with 38 lbs in our temperate waters, all of it currently on my belt (which I've never lost in 52 years of diving). However, I've given thought to splitting the weight between weight pockets and my belt.

 

[Bob DBF]

I dive with 38 lbs in our temperate waters, all of it currently on my belt (which I've never lost in 52 years of diving). However, I've given thought to splitting the weight between weight pockets and my belt.

38# on a belt is a bear, I had to split it up years ago because it was hard on the back. My limit now is 27# when I'm Abalone / free diving and 18# on SCUBA. I almost lost my belt once, if we meet in person ask me about it because it is both embarrassing and hilarious. It should be in the Accident forum but I'd take too much heat and you would think I would have known better by now.


Bob
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I may be old, but I'm not dead yet.

 

[Roatan Joe]

Although not entirely relevant to the original post, there are some good things to talk about in this deco stuff.

Adobo implies that you can't go into "accidental" deco, and he is making a point. When you did this second dive in Cozumel, it seems pretty clear that you didn't plug the briefed depth into your computer's dive planning function, to see what kind of no-deco time the computer would allow you, so you could anticipate having to ascend before you looked at the gauge and realized you no longer were allowed to. In addition, it seems an unavoidable deduction that you weren't monitoring your no-deco time very well, or you would have seen it ticking down and requested to get shallower before you ran out of time.

You can't count on the divemaster's computer (or whatever he is using) to match the output from yours. Decompression is not an exact science, but rather an exercise in mathematical modeling of nitrogen dynamics in the body. There are different models, and they make different assumptions, and result in different answers. This is what people mean when they talk about "conservative" or "liberal" computers -- conservative computers use an algorithm to compute nitrogen loading and offgassing that results in shorter no-deco times than liberal computers do. The differences can be substantial. I remember looking at a table in Lippmann and Miller that compared no-deco times from various models, and noting that, at one depth, they varied by eleven minutes. This means that a person using the conservative model would run out of no-deco time eleven minutes before anybody else in the group.

That brought a humorous memory to mind from a couple of weeks ago. I was diving in Cozumel and had an Oceanic primary computer on my wrist and a Suunto Zoop on my console as backup. It was the second dive of the day and was pretty deep. The Zoop went into deco and then into error mode. My Oceanic had no less than 8 minutes at any time during the dive . When I got to the boat the Zoop was beeping non-stop and got the attention of the crew. I gave them a sheepish smile and said I was okay and showed them my primary computer on my wrist. Zoop computers are great, but they are very conservative. I should have paid closer attention to the Zoop, because I didn't like not having a backup computer for the next two days.

 

[Peter69_56]

Well an interesting subject which I have just recently experienced. Doing a 55m dive on the Repulse with wing/twins 18/40 mix, 2 deco tanks 40% & 100%, 3mm wetsuit and 9 lb of weight on a weight belt.

At 24 metres on the ship anchor line at deco stop No. 1 killing time and my dive buddy taps me on my shoulder and points to an orange weight belt disappearing into the gloom. Suddenly I realise its mine. Now I am nervous, a strong current is running at about 5-6 knots so if I lose the line I am toast. At 12 metres we have tied off a light current line running back to the deco bar below the ship. I slowly complete my deco to 12m, realising the more time I spend breathing the more buoyant I become. I feel a bit floaty at 12m, so do I continue up the anchor line which is being tossed about with the strong swell and waves so risk being pulled up and down and lose the anchor line or risk going along the current line which is light and somewhat slack with the potential to lose it or lose buoyancy. I chose the current line as I didn't feel too buoyant at the time and believe its the better risk. Got back to the deco bar OK and then a standard deco to the surface.

My wing crotch strap did not catch the belt, most probably because of the few weights on the belt. Something I did right was to carry all my required gas for the dive rather than relying on the 100% mix provided at the 6m deco bar.

My thoughts at the time were, take care and don't lose the anchor line or current line, if I do then maintain some depth while the appropriate gas lasts to ensure I stay down and complete as much of my deco obligation as possible, then when I am low on travel and back gas, come up to 6m and maintain it if possible while completing deco (swim down to maintain depth at 6m and no deeper otherwise oxygen toxicity will be a problem), if not then remain on 100% mix even though I break surface and remain on it while the gas lasts, remembering that the current will take me and it will be some time before I get picked up. Remaining on oxygen will minimise getting bent or minimise the effects.

If I use a dry suit I use a weight harness. If I use a BCD I have integrated weights and non drop weights. Due to the combination I had, it didn't warrant a weight harness hence the belt. Murphy's LAW if it can it will. Be prepared mentally for Murphy.