With no weights, what do you ditch?

[Web Monkey]

I weigh about 225, and dive with a steel 95 tank, a 5 mm wetsuit (in the summer) and in fresh water use about 4 lbs of weight.

This is all great, and makes me very happy, but I'm wondering what happens in case of a BC failure. I'm not completely certain that ditching 4 lbs would make me positively bouyant at depth.

I was wondering if adding fixed floatation (chunk of closed cell foam) to my BC would be a good idea, or a bad idea, and if anybody has any ideas on the subject.

Also, on a completely unrelated note, I set up a 5p@mtr@p on my mail server that reports to a bl@ck list, so please feel free to use curmudgeon@newfrontiersw.com for an email address anyplace you think might send 5p@m.

 

[Epinephelus]

Diving steel tanks often creates a situation where the diver has no ditchable weight. So, to provide a backup way to get positive, (in a "normal" recreational rig the BC is one, dumping the weights is the other) we must replace the weightbelt with something positive - a dry suit in the winter, a lift bag in the summer are the two I use.
One thing I would *not* do is add permanent buoyancy just so I could carry ditchable weight.
E.

 

[Web Monkey]

Epinephelus once bubbled...
Diving steel tanks often creates a situation where the diver has no ditchable weight. So, to provide a backup way to get positive, (in a "normal" recreational rig the BC is one, dumping the weights is the other) we must replace the weightbelt with something positive - a dry suit in the winter, a lift bag in the summer are the two I use.
One thing I would *not* do is add permanent buoyancy just so I could carry ditchable weight.
E.

A lift bag sounds good (especially since I've got one )

 

[Don Burke]

Four pounds won't make you positive.

The swing on a 95 (with air) would be about six pounds, depending on how much you fill it and how low you drain it. Wetsuit compression would be substantially more than that unless you are diving Rubatex.

If you're using a backplate system and using steel, a switch to aluminum will move about five pounds to your belt.

In any case, the liftbag should serve you well. I certainly wouldn't fiddle with foam.

 

[Atticus]

There are some good points/suggestions above.

The one thing that I wanted to add though is that you may not actually wish to become positive, but to be close enough the neutral that you can swim to the surface.

I shudder at the thought of ditching all weight and rocketing to the surface.

Assuming you're not overweighted to begin with ...
You will be heaviest when you first start your dive - still lots of gas in the tank, and at your deepest depth. At this point you may be 10-12 lbs negative between wetsuit compression and compensation for tank/gas weight change.

If you dump four pounds then the question is can you comfortably swim 6-8 lbs to the surface?

That being said, I would give a strong vote for either a drysuit or lift bag (with a dump).

 

[USMC Diver]

Epinephelus once bubbled...
in a "normal" recreational rig the BC is one, dumping the weights is the other
E.

If you dump your weights and can't go up, offset your weight with air in your BC. Remember, your BC is not an elevator. Use those big peaces of plastic attached to your legs to propell yourself to the suface in the case of an emergancy. Remember, the air in you BC, your Exposure Suit, and such will be come more boyant as the expand and decompress.


:mean:

 

[Web Monkey]

USMC Diver once bubbled...


If you dump your weights and can't go up, offset your weight with air in your BC. Remember, your BC is not an elevator. Use those big peaces of plastic attached to your legs to propell yourself to the suface in the case of an emergancy. Remember, the air in you BC, your Exposure Suit, and such will be come more boyant as the expand and decompress.
:mean:

Acutally, I raised the question because of a BC failure I had in Cozumel, where it was impossible to inflate the BC because the inflator hose tore off the fitting at the shoulder.

In fresh water with a steel tank, I only use 3-4 pounds, which I don't believe would be enough to make me positively bouyant at any significant depth.

The lift bag mentioned in a previous message, sounds like a great idea, though, since it's simple enough that it should always work.

Swimming also works, but doing a deco or safety stop is difficult.

 

[DA Aquamaster]

The problem with a saftey or deco stop after ditching weight is usually not going to be negative bouyancy. At 10-15 ft wet suit compression is pretty minimal and with 4 lbs dumped and a near empty tank, you may not be able to stay down. Making the stop deeper than normal may be required to avoid the strain of having to swim down to maintain depth.

Ditching your weights is something that in my opinion should be an option of absolute last resort as in many cases it will develop into an unchecked ascent all the way to the surface.

Most divers in good shape can swim up 10-15 lbs of weight and with wet suit compression the load gets lighter as you go up so you don't have to sustain the initial weight all the way to the saftey or deco stop.

Proper weighting is also important - a properly weighted diver should be neutral at 10-15 ft. with 500 psi in the tank. This will make a deco or saftey stop do-able without a functioning BC. Much of the problem comes from divers being over weighted and many instructors aggravate the problem by over weighting students in order to get them under easier. (The solution should be to get them to stop moving their hands and kicking their feet - not adding more lead.) The misinformed students then dutifully note the weight they "need" in their log books and often continue to dive over weighted for years.

A lift bag is in my opinon preferable to dumping weight if you are very deep and cannot swim up to the surface. Be careful clipping the bag to yourself, you need to be able to dump air from the bag or unclip the bag if you can't dump air and the ascent gets out of control. Rather than just ride the bag up, just use it to reduce the weight you need to swim up and dump small amounts of air to maintain a bit of negative bouancy all the way up. This will help prevent things from getting out of hand in the last 30 ft. of the ascent. And if you are properly weighted, the bag should be empty and you should be near neutral at 15 ft.

 

[Wristshot]

would be another alternative, and we all carry those don't we?

Excellent advice from several people, but I don't carry a lift bag with me. (my buddy does) I am just thinking that a sausage could provide the small amount of bouyancy necesary to get moving.

Of course I don't have the "problem" of no lead, I carry a lot *sigh*

Wristshot

 

[Web Monkey]

Wristshot once bubbled...
would be another alternative, and we all carry those don't we?

Excellent advice from several people, but I don't carry a lift bag with me. (my buddy does) I am just thinking that a sausage could provide the small amount of bouyancy necesary to get moving.

Of course I don't have the "problem" of no lead, I carry a lot *sigh*

Wristshot

I used to take quite a bit more, but then one day Mr. Obviousman paid me a visit, and I suddently realized that if I ate less crap and got more exercise, I'd lose weight

It's not like I hadn't heard it my whole life, but for some reason, it suddenly made sense