Neat Little Tricks Are Good to Know

[Lobzilla]

I'm talking about one or two pounds. Not 9. And I might be biased by too much cold water diving, with a lot of lead to sink the dry suit - a couple pounds is just a small percentage of your total weight.

If you're two pound overweight, you'll end up with a two pound bubble in your BC. Even if you forget to purge from 30ft to 10ft, you'll end up at +3lbs at 10 ft, which isn't enough (by far) to send you in an uncontrolled ascent, and can be fixed easily.

If you're two pound underweight, you'll have to do your whole safety stop at +2lbs. Which means constantly kicking or holding to an anchor line/kelp frond/rock. Not fun, and potentially dangerous if an earlier incident causes you to come back below 500psi or you're assisting another diver.

Grossly overweight is no fun either, but if I'm not sure about my exact weighting I'd rather shove one more pound in a pocket and ditch it for the next dive than risk struggling for the whole end of a dive.

Thanks for explaning. So, an easy way to get in the ballpark with unfamiliar tanks/equipment would be to have enough weight to hover just below the sfc with dumped BC and suit, then add 8lbs of lead for every 100cuft of air you carry and another 1 - 2 lbs for safety?

 

[The Chairman]

Thanks for explaning. So, an easy way to get in the ballpark with unfamiliar tanks/equipment would be to have enough weight to hover just below the sfc with dumped BC and suit, then add 8lbs of lead for every 100cuft of air you carry and another 1 - 2 lbs for safety?

Don't do that. You'll be way overweighted.

At the beginning of the dive with NO air in your BC and with both your legs and arms crossed, the top of your head should be just awash. Add a pound of lead for every inch you stick out of the water. You will find that you are close to perfect at your 15-20FSW safety stop with 300-500 psi left in your tank. Boyle's Law will see that you are dense enough to hover at that point.

The best way to shed lead? Stop swimming with your hands!!! Fold them together!
The best way to improve your air consumption? Stop swimming with your hands!!! Fold them together!
If you aren't sure what I mean, look at my avatar. That's really how I dive unless I am holding a spear/light/etc.

 

[D_B]

I think this might be helpful in determining a round about amount to start with
　

I got this formula for weighting from my open water instructor many years ago.
A couple of caveats:
The thermal calculation is a pound for every millimeter generally worn on the torso;
For fresh water use .04 in place of .05.

Body weight X .05
4lbs. for an AL 80 tank
1 lb. of weight for every mm of thermal protection



Again this formula puts one in the ballpark for proper weighting. But it's a starting point. Obviously experience, add-on gear, conditions, body composition, etc all play a part in proper weighting. I use this with students primarily to show them a target weight.
Dr Neil

That formula works out to 20lbs for me and I dive 14lbs with a steel HP100 (-2lbs so remove 6lbs from the calculation) and a 7mm suit so I think thats pretty darn close

 

[aquaregia]

2lbs+2lbs/mm+tank buoyancy returns my current weighting for naked, 3/2 and 7mm. Didn't realize until I tried to apply D_B's formula, kinda cool.

 

[D_B]

2lbs+2lbs/mm+tank buoyancy returns my current weighting for naked, 3/2 and 7mm. Didn't realize until I tried to apply D_B's formula, kinda cool.

Thanks but it's not mine ... it's Dr Neil's formula

 

[SubMariner]

Katy and I have a friend who is a Navy EOD diver. Katy got to chatting with him the other day about scuba, and she mentioned that she worries about jumping in with her tank turned off.

"Oh, that's easy," he said, "just reach back and turn it on."

"I can't reach the valve, at least not in a 7 mm wetsuit." she said.

"Well," he said, "you reach around with one hand and grab the bottom of the tank and pull it up and sideways. Then you reach over your shoulder with your other hand and you should be able to reach the knob."

I thought this was a pretty neat trick, and I wondered if anyone else has done it, or if anyone knows any other neat tricks.

IMHO the person who jumps in with their tank turned off has not done a proper pre-dive check.

So rather than labeling it a "pretty neat trick" I'd call it "Oh S##T! NOW what do I do?"

Hopefully, your in-water buddy can help rectify the problem. If not, I guess you need to practice this "not-as-easy-as-it-sounds trick".

 

[Mike Boswell]

Don't do that. You'll be way overweighted.

At the beginning of the dive with NO air in your BC and with both your legs and arms crossed, the top of your head should be just awash. Add a pound of lead for every inch you stick out of the water. You will find that you are close to perfect at your 15-20FSW safety stop with 300-500 psi left in your tank. Boyle's Law will see that you are dense enough to hover at that point.

The best way to shed lead? Stop swimming with your hands!!! Fold them together!
The best way to improve your air consumption? Stop swimming with your hands!!! Fold them together!
If you aren't sure what I mean, look at my avatar. That's really how I dive unless I am holding a spear/light/etc.

Ahhh, so THAT's why you do that.

All this time, I thought you were praying .... that DCBC wouldn't start any more diver training threads.

 

[--tom--]

A mouthful of water forced through a flooded second stage will clear it to get a breath (in case the purge button is blocked for some reason).

 

[The Chairman]

A mouthful of water forced through a flooded second stage will clear it to get a breath (in case the purge button is blocked for some reason).

??? Never fight water with water! A mouth full of AIR can clear that reg, but using a mouth full of water will still leave the reg full of water.

 

[aquaregia]

If you suck the water into your mouth it'll get replaced with air though, right?