Better buoyancy tips

[HybridDiver]

Hello
I would like to know some of you guys Boyancy tips, This would be a really good thread to open for new divers like I and for those who are learning to dive.
Lets here them
Chris

 

[Mike126]

Having completed the PADI Bouyancy Class I'm now certified to tell you what I've learned!

The key is only use as much weight as you need to keep you at eye level in the water with about 500psi of air in the tank. The class is basically all about finding the optimal amount of lead to carry and where to place it to get effective trim. Start with 10% of your body weight and then make adjustments for the wetsuit thickness SW/FW etc. You want to remove weight so that an empty tank will get you to float at eye level.

What I found was unless you want to run this check at the end of a dive, start with being a few pounds heavy so that you just start to sink with a full tank and little/no air in your BC.

For good trim, I place 10% of my weight in weight pockets on the back of my BC next to the tank and the rest goes in the side weight pockets. Some people need to place the weight on the back a little higher or move the tank up on their back a little. You pretty much have to play with this when you are tuning your bouyancy.

Anytime you add or remove wetsuit thickness or pieces (gloves or hoods etc.) you may have to make minor adjustments to your weights.

All of this is much easier with a buddy to assist you. Also keep very detailed notes so you can repeat your setup for each dive.

Hope this helps....

 

[HybridDiver]

Thanks mike for posting, That helps alot.
Keep Em Coming.
Chris

 

[evil_xander]

Having completed the PADI Bouyancy Class I'm now certified to tell you what I've learned!

The key is only use as much weight as you need to keep you at eye level in the water with about 500psi of air in the tank.

Question, how can you than make the safety stop at 3 m, and keep neutral with the tank nearly empty? By the logic of this, you'd be positive and wouldn't be able to make the stop. Am I missing something?

 

[HybridDiver]

Thats why you add the amount of weight to offset it. My steel 100 is 2.3 positive so I add 2.3 to the weight and now I find I can make that S stop.

 

[pir8]

Key not mentioned with empty tank bouyancy check at the end of dive is floating at eye level While Holding a Normal Breath. That way when you exhale you will become negative and sink

 

[GA Under Water]

Question, how can you than make the safety stop at 3 m, and keep neutral with the tank nearly empty? By the logic of this, you'd be positive and wouldn't be able to make the stop. Am I missing something?

What he explained will make you neutral at 500 PSI. being eye level at 500 psi is optimal. With an AL 80 it is more buoyant at 500 PSI than at 3k. Hense the eye level at 500. If you are eye level at 3k and sink on the exhale then when you get to 500 PSI you will be positive by about 4 lbs. causing a positive buoyancy at the end of the dive and making a diver have to hold a line to stay at 15 ft.

 

[Mike126]

OK OK So I missed a few details!!! That's why I paid $90 for my PADI Cert and you are all getting free advice!

Good points. Make sure if you start with a full tank you offset your weight accordingly. Its better to be slightly negative and use the BC than slightly positive and have an uncontroled ascent.

The other thing to work on (I need to practice this more) is using your lungs for fine tuning. For me this is harder than it sounds since I tend to not take full breaths when I do this. It's good to take very deep breaths every so often to clear your lungs and help you relax. I once dove with a Cardiologist than could pace his breathing rate so well he could easily get over an hour's time on a AL80 and 60+ feet.

 

[dave4868]

Hello
I would like to know some of you guys Boyancy tips, This would be a really good thread to open for new divers like I and for those who are learning to dive.
Lets here them
Chris

If you're asking how to determine proper weighting for your particular dive gear, I'd go with the following:

• Use an empty tank, bcd empty.
• Adjust weight to be able to float vertically with eyes level with the surface with a full breath.
• If you use a full tank, adjust weights as above, then add weight equal to the calculated weight of the air in that full tank, since that weight may be mostly gone near the end of the dive (figure 0.08 lb per cubic foot, I believe).

Just for fun, I reviewed my PADI OW manual (1990, 1994 copyright) to see what they had to say.

I was surprised to see their instructions were for full tank, eyes level at the surface with a full breath.

They added the observation that one would finish the dive positively buoyant!

I think they probably assumed those guidelines would provide a safety factor for the typical newbie wetsuit diver who would be doing a 10-foot safety stop with at least 500 psi left, and compression of the neoprene would allow him to be able to be neutral until ascending the last ten feet, when he would become positive.

How about sharing what your OW manual says about determining proper weighting? That might be interesting.

I wonder if PADI's guidelines have been updated from the above. Anybody know?

Now, if you're asking about buoyancy control tips, that's easy: get your weighting optimized for neutral with an empty tank and practice using small adjustments with your BCD until you get good at it.

Won't take long.

Good luck!

Dave C

 

[TSandM]

A couple of things I figured out when I was starting -- A good buoyancy check while you are diving is to stop moving. If you quit finning and sink, then you're negative and need to add some air somewhere. This is a really common thing for new divers, particularly if they are not in perfect horizontal trim. You kick, and the kick pushes you up, so to stay level, you have to be negative. It's inefficient and uses a lot of gas.

The frog kick is really nice for this, because it has a built-in "glide" phase which will give you the feedback. Also, as you dive along, take a breath and see if you rise; if you don't, you're negative. Blow your breath out and see if you sink -- If you don't, you're positive and need to vent a little. This is VERY useful while you are ascending -- You should be able to stop your ascent with your breath (or your descent, for that matter, unless you're doing a fast drop somewhere). If you breathe out during ascent and don't stop, you need to vent a little bit -- you're too far from neutral.