70 replies to this topic

[scubahoney]

[Walter]

Same principle, Don. I just did't want to go there. LOL!

[Walter]

I never said you LOOKED like Yoda..you are just all-knowing like the creepy little midget. Don't worry, you don't resemble him at all! LOL

I know, darlin', I was just busting your chops a tad. How many fingers does Yoda have?

[Walter]

Sure the .0006 might be taking it to the ultra-geek level, but weren't we trying to prove it's more science than art?

Yes, but we want to keep it to the area of science that's useful. We can also take salinity and water temperature into consideration, but it wouldn't really help. Getting proper weighting is science, not art. Precision buoyancy control is art (sorry Amber, but we'll all help you with it).

[scubahoney]

Ok..you better! You are starting to confuse me again!
Yoda has 3 fingers?? Maybe.

[Walter]

Ok..you better!

I promise. You just gotta go on a trip I'm on. I know you'll have lots of volunteers on other trips. We have helpful divers here.

[Diverbrian]

Sorry Walter!!!

I just re-read your post and saw you are recommending this be done with a tank at 500 psi, so you are totally correct. My bad.

I've always recommended using full tanks, though, because this way you can do a check before the dive, and people are usually ready to go with a full tank. Either method works though.

There are people who advocate doing this with a nearly empty tank vice five hundred pounds.

The five hundred pounds is a reserve. If something happens, it is there to cut into for safety stops (instead of blowing them off because you are afraid to get back to the boat with less than 500 psi and something went wrong that cut into your gas supply). Being perfectly weighted at 500 psi, in theory, may make you light for the safety stop at 15 ft. if this happens.

I happen to think of weighting and buoyancy control in the same paragraph as gross over/under weighting will tend to lead to severe problems with buoyancy control and I have had issues when my drysuit wouldn't vent completely which left me light at the safety stop.

Oh, and I don't think that there is a person on this board that wouldn't help another diver with weighting and buoyancy control if they were able. Obviously Walter has sat down and figured this out by formula.

[Walter]

The five hundred pounds is a reserve. If something happens, it is there to cut into for safety stops (instead of blowing them off because you are afraid to get back to the boat with less than 500 psi and something went wrong that cut into your gas supply). Being perfectly weighted at 500 psi, in theory, may make you light for the safety stop at 15 ft. if this happens.

500 PSI in an AL 80 weighs about 1 lb. If you have an empty tank at 15 feet you would be under weighted by 1 lb. You figured your weighting with completely expanded lungs. You have a lot more than 1 lb leeway in your buoyancy just by varying your breathing. If your tank is empty, you'll still be ok on buoyancy (you will need another air source, however).

When diving with a steel 72 and no wetsuit, I'm perfectly neutral with no weight. I use my BC solely to hold on my tank. The air in my full tank weighs almost 5 lbs. When I'm down to 500 PSI it weighs about 1 lb. I've become about 4 lbs more postive over the course of the dive. Actually, I would have become 4 lbs more postive over the course of the dive but I haven't because I have changed my breathing pattern to compensate. I don't use my BC to control my buoyancy during the course of the dive. I have to do this when diving vintage, as there is no BC. A 4 lb change is not significant to an experienced diver. A 1 lb change is not significant to any diver with the basics.

[Diverbrian]

I see your point Walter. I was allowed to try vintage gear once in a pool and it was unique to have to do all of my buoyancy adjustment with my lungs.

I can compensate when I have to. I guess that I don't worry about weighting because my doubles are so dang heavy that I am overweighted the minute that I get into them even with the extra buoyancy added by drysuit and thermals.

In my "recreational" gear, I wrote down most of my weights early on before I got rid of that psychological "breath retention" underwater that many of us have. I quit trying to adjust the weight down when I had an incident with underestimating the bouyancy added by more insulation underneath my drysuit. I got down great, but couldn't do the safety stop, especially when my vent wouldn't vent the gas out completely. I have one buddy who figures that he is properly weighted and he has to kick down about 10 ft. to sink at the start of a dive. But he manages his safety stops just great, so I don't say anything to him. As you said, four pounds leeway is very doable with the lungs.

Also, I think that I said near empty (And if I didn't I meant to). If you are empty, then you are working with a buddy to maintain that safety stop for obvious reasons.

[Walter]

Also, I think that I said near empty (And if I didn't I meant to). If you are empty, then you are working with a buddy to maintain that safety stop for obvious reasons.

My reference to an empty tank was to demonstrate the buoyancy differences in the worst case.

[scubahoney]

Hey Walter, I never said you LOOKED like Yoda..you are just all-knowing like the creepy little midget.  Don't worry, you don't resemble him at all! LOL

Sheesh! Now I'll be picturing little green midgets with big ears running around saying "Use the force, Darlin"!!!

I think you nailed that statment on the head CT.

[Coo's Toe]

I'm picturing me in a Luke Skywalker context telling Walter how I'm not scared, and just before I do my giant stride off the stern, Walter looks me deep in the eyes and gives me his best Yoda impression.

"Mmmmm. You... will.... be..."

[Coo's Toe]

Come to think of it... if Luke had owned a big orange liftbag, he might not have needed Yoda's help getting his spacecraft out of the swamp! LOL. My imagination is running wild with really awful Star Wars meets scuba diving scenes....

Was someone talking about straying off topic earlier? There I went!

[scubahoney]

weights!!!! discuss weights!

[Coo's Toe]

weights!!!! discuss weights!

What more can we say about proper weighting? We already answered the questions, so let's flirt and talk about Star Wars!

( I just hooked up a tank and sampled a few breaths off the regulator. I think I even sound like Darth Vader... )

If you have any serious questions about weights, I'll be glad to get back on topic.