To weight or not to weight

[nwh20]

Dpaustex, what a great bunch on info for us newbies to digest! Good, practical info about how to deal with things on a commercial dive boat is especially appreciated. But I never thought about practicing mask removal at depth. I can see the benefit to alleviate hitting your panic button, but how often does that lead to losing your contacts? Maybe the pressure as you get deeper actually pushes them on your eyeballs harder and they're less likely to be swept away.

Sounds like you are talking about two things, mask removal and BC removal. Are you advising to practice completely removing your BC every dive as well? That's a scary thought at 60'! Maybe that's exactly why I need to practice it.

 

[PatrickDS]

Excellent thread with lots of good stuff. Like many that have posted here I'm a newbie. Got my OW and AOW earlier in Feb. Getting my weight right has been frustrating but understand that it is an on-going learning process, so I accept it and will just keep working on the skill as well as many others. The information I've gotten here so far has helped a lot - thank you everyone!

 

[BrotherBear]

...
I was having trouble with buoyancy in the freezing cold water and visibility was just 3-5 feet with lights. After accidentally popping up to surface, I went back down and ended up losing my buddy and instructor on the ocean side of a breakwater wall. That's because the instructor took my buddy off in another direction, although he thought they should stay there where they last saw me.

...

Is it just me or is there something seriously wrong with this picture? Should not the instructor have thumbed the dive when he lost one of his two students? In low vis water wouldn't the best course of action been to surface and look for bubbles instead of guessing on a direction and heading off on a search where the lost diver could be missed only 10 feet away? I'm thinking nhw20 needs a new instructor.

 

[nwh20]

Brother Bear, when I disappeared my buddy thought they should surface and asked the instructor if they should go up, but she shook her head and led him under the breakwater to the shore side, away from where I last was, for some reason that he couldn't fathom. Then later she brought him back to the ocean side again, but of course by then I was gone.

My buddy and I both had the same thought, why did she do that? She never did explain, and all I wanted to do was get out of there so we never had a discussion about what happened. We also felt that there were other mistakes made, like not providing us with brighter lights (some were on the dim side) and maybe even a tether (which I'm now thinking about for the manta ray dive I hope to do in a month), but being newbies, you don't question your instructor at first. In retrospect, you hope to learn something from every dive. But I have to admit, I don't have much trust in that instructor to watch my back.

I've heard it said on this forum that you should not count on your DM to keep you safe, but shouldn't you be able to count on your instructor to do that?

 

[BrotherBear]

Brother Bear, when I disappeared my buddy thought they should surface and asked the instructor if they should go up, but she shook her head and led him under the breakwater to the shore side, away from where I last was, for some reason that he couldn't fathom. Then later she brought him back to the ocean side again, but of course by then I was gone.

My buddy and I both had the same thought, why did she do that? She never did explain, and all I wanted to do was get out of there so we never had a discussion about what happened. We also felt that there were other mistakes made, like not providing us with brighter lights (some were on the dim side) and maybe even a tether (which I'm now thinking about for the manta ray dive I hope to do in a month), but being newbies, you don't question your instructor at first. In retrospect, you hope to learn something from every dive. But I have to admit, I don't have much trust in that instructor to watch my back.

I've heard it said on this forum that you should not count on your DM to keep you safe, but shouldn't you be able to count on your instructor to do that?

I'm very much a newbie myself but, yes, I believe that an instructor is a much more responsible position than a DM...ESPECIALLY to a brand new diver.

 

[dandy621]

Thanks guys, these are excellent points and have helped me a ton!

 

[Black Water Diver]

Sounds like a picture perfect class room explanation to me!
Patrick Wirtz, PADI instructor

 

[Bubbletrubble]

Now the issue is when you get in salt water, the water is slightly denser, which makes you more buoyant than you were in the pool (but not by much, about 3%). So if you happened to have it to the ounce in the pool, you'll need another pound or so in salt water.

The difference in buoyancy from fresh to salt water is about 2.5%. That would be 2.5% of your entire weight (person + all of your gear). For most people, this means adding 5-6 lbs. when going from fresh water (pool) to the salt water (ocean)...provided that there are no changes in gear.

The danger of being underweight is if you are diving aluminum cylinders, which go slightly buoyant when they are empty. Most boats want you back on at 500 psi, which should be fine. But if you're pushing the limits, you'll probably want to be 2-3 lbs negative at the start of your dive. In other words, if you are doing a weight check, with a full cylinder, get the weighting right for floating eye-level. After that, add 2-3 lbs to make sure you stay down as your cylinder starts to go buoyant toward the end of the dive.

The danger of being underweighted exists regardless of the kind of tank you are using. It doesn't matter if it's aluminum or steel. You really should weight yourself so that you are negatively buoyant by the weight of your gas at the beginning of the dive. It's helpful to know the "buoyancy swing" of the tank you're using. Buoyancy swing is the difference in buoyancy between full and empty. For an AL80 tank, that's about 6 lbs. (-2 lbs. full, +4 lbs. empty). Follow dpaustex's description of how to do a proper weight check (no air in BCD, normal breath, water at eye-level).
If you are using a full tank during the weight check, you'll need to add enough lead to compensate for the buoyancy swing. Understand that you need to have enough lead so that you can be neutrally buoyant just below the surface (at the very least at safety stop depth) with an empty tank. No adjustments are necessary if the weight check is done with a near empty tank.

 

[austin.takahashi]

Very well-written with a nice attitude. Will take your advise into consideration and hope not to drown in the near future. Happy diving everyone!

 

[NAM001]

The difference in buoyancy from fresh to salt water is about 2.5%. That would be 2.5% of your entire weight (person + all of your gear). For most people, this means adding 5-6 lbs. when going from fresh water (pool) to the salt water (ocean)...provided that there are no changes in gear.

The danger of being underweighted exists regardless of the kind of tank you are using. It doesn't matter if it's aluminum or steel. You really should weight yourself so that you are negatively buoyant by the weight of your gas at the beginning of the dive. It's helpful to know the "buoyancy swing" of the tank you're using. Buoyancy swing is the difference in buoyancy between full and empty. For an AL80 tank, that's about 6 lbs. (-2 lbs. full, +4 lbs. empty). Follow dpaustex's description of how to do a proper weight check (no air in BCD, normal breath, water at eye-level).
If you are using a full tank during the weight check, you'll need to add enough lead to compensate for the buoyancy swing. Understand that you need to have enough lead so that you can be neutrally buoyant just below the surface (at the very least at safety stop depth) with an empty tank. No adjustments are necessary if the weight check is done with a near empty tank.

Aluminum steel or plastic tank the only thing that is important is the weight swing of the gas. apx 8lbs per 100 cu ft. I by the way weight to be neutral with 300 lbs and plan to get out at 500. that leaves me a 1/2 lb heavy at 500. then add
weight up to the nearest lb. or nerutal at 500 and add a lb 6 of one half a dozen of the other. fresh water i ballast in a pool sea water i have a weight correction to add to fresh water weithting. for me it is 16 lbs for a given configuration. i then fudge for personal wieght gain or loss. i am always close enough to not waist a blue water dive on a boat. my steel 95's full is 2500 so i use 80% of air before getting out thats 70 cubes lighter that when entering the water. about 5-6 lbs.

oops sorry i should have read your post closer,, i missed the part of ""It doesn't matter if it's aluminum or steel"". you are absolutely right....


for what it is worth.

regards