To weight or not to weight

[robnelson13]

I'm in the same boat. Been certified since '95 but only gone diving once in '99 before moving to Guam. Finally have my own gear and plan on going out a couple times a week for the next 2-3 hundred years. My wife and I took a scuba tune-up class a couple of months ago, and we just took the peak performance buoyancy class. Boy do I have a long way to go!
I'm a little confused. On the second dive, when I dumped the air in my bc and exhaled to descend, that was the last time I had air in my bc until I inflated it again upon surfacing at the end of the dive. All minor adjustments were made by breathing. If I wanted to descend or ascend more than a few few feet I would just fin there nice and lazy like. Toward the end of the dive I found that I had to exhale really hard if I wanted to drop a little bit, and and I started getting nervous that the only way to keep from rocketing to the surface was to go inverted and kick down. Didn't happen though. I even checked again after surfacing to see if I could descend on exhale and I could although I had to blow out hard to do it..
my initial weight check was with full tank so I added 5 lbs per my instructor, then after finally surfacing check it again and my instructor suggested another pound and I opted for2'just for balance sake.
After all this long winded narrative my question- is it normal to use no air in your bc submerging to surfacing? I seem to remember being told that the deeper you went, the more you would have to add air to stay neutral, then dump as you ascended ( by finning up, of course). I thought it was kinda fun making depth changes just by breathing. Am I just being a dumb newbie?

 

[gcarter]

I'm in the same boat. Been certified since '95 but only gone diving once in '99 before moving to Guam. Finally have my own gear and plan on going out a couple times a week for the next 2-3 hundred years. My wife and I took a scuba tune-up class a couple of months ago, and we just took the peak performance buoyancy class. Boy do I have a long way to go!
I'm a little confused. On the second dive, when I dumped the air in my bc and exhaled to descend, that was the last time I had air in my bc until I inflated it again upon surfacing at the end of the dive. All minor adjustments were made by breathing. If I wanted to descend or ascend more than a few few feet I would just fin there nice and lazy like. Toward the end of the dive I found that I had to exhale really hard if I wanted to drop a little bit, and and I started getting nervous that the only way to keep from rocketing to the surface was to go inverted and kick down. Didn't happen though. I even checked again after surfacing to see if I could descend on exhale and I could although I had to blow out hard to do it..
my initial weight check was with full tank so I added 5 lbs per my instructor, then after finally surfacing check it again and my instructor suggested another pound and I opted for2'just for balance sake.
After all this long winded narrative my question- is it normal to use no air in your bc submerging to surfacing? I seem to remember being told that the deeper you went, the more you would have to add air to stay neutral, then dump as you ascended ( by finning up, of course). I thought it was kinda fun making depth changes just by breathing. Am I just being a dumb newbie?

What were you wearing for exposure protection? The less compressible neoprene you wear, the less you need to adjust for depth.

 

[sibermike7]

the deeper you went, the more you would have to add air to stay neutral, then dump as you ascended ( by finning up, of course). I thought it was kinda fun making depth changes just by breathing. Am I just being a dumb newbie?

Lots of variables. what was the depth? Water temp? What kind of exposure suit (GCARTER already asked)?
All these affect buoyancy.
Did you have a BCD or wing? I am assuming BC. I hate those things!
Used to have a devil of a time getting all the air out of a Mares that I had, so it is possible that you were not successful in emptying the BC. Have used a wing every since and HATE to use a BC when I must.

I LOVE diving in FL (warm water) as opposed to diving in Nordic countries under the ice, because I don't even need a weight belt, but either way, you should be able to move a bit in the water column with breathing.

Keep in mind that if you are using AL80, they swing from neg to pos buoyancy during the dive.

The idea that you need to exhale to begin your dive is not always true. If you have to exhale to descend with a minimal exposure or a compressed suit, you might be light especially if using AL80.
The reason the "rule" of exhaling to descend came about was that pretty much all suits in the past retained A LOT of air bubbles until compressed a bit. Once the air was squeezed out the diver became neg buoyant. I.e. if the diver descended to 10 feet then resurfaced immediately, he would find that he didn't need to exhale again to descend again. Make sense?

 

[robnelson13]

Thanks for the info, I had forgotten about wet suit compression at depth since we are cursed with such rotten water conditions here.
I'm in Guam, water temps average about 86 degrees year round (bummer, huh?). I wear swim suit and a t-shirt, booties, and now have an Oceanic Axiom i3 BCD. I am extremely naturally buoyant, I can float on my back with both hands and feet out of the water and never have my face get wet (wearing just swim suit). Last dive that I described I was at 8 lbs in the bc. I think I might add a 1 pound ankle weight around my tank valve to try to trim to keep my feet from sinking when I'm not moving.
When I certified in '95, it was in Puget Sound, 7mm full wet suit, hood, gloves, booties, and a whoppin' 40lbs on a weight belt per my instructor. I was also about 30-40 lbs lighter and mostly muscle ' cause I was still active duty army and ran constantly. I thought that was the norm for a weight belt at the time until I talked to some instructors at other dive shops and was told that was nuts.
By the way, max depth last dive was 49 feet, and was using a rented AL80 tank.
.

 

[sibermike7]

Thanks for the info, I had forgotten about wet suit compression at depth since we are cursed with such rotten water conditions here.
I'm in Guam, water temps average about 86 degrees year round (bummer, huh?). I wear swim suit and a t-shirt, booties, and now have an Oceanic Axiom i3 BCD. I am extremely naturally buoyant, I can float on my back with both hands and feet out of the water and never have my face get wet (wearing just swim suit). Last dive that I described I was at 8 lbs in the bc. I think I might add a 1 pound ankle weight around my tank valve to try to trim to keep my feet from sinking when I'm not moving.
When I certified in '95, it was in Puget Sound, 7mm full wet suit, hood, gloves, booties, and a whoppin' 40lbs on a weight belt per my instructor. I was also about 30-40 lbs lighter and mostly muscle ' cause I was still active duty army and ran constantly. I thought that was the norm for a weight belt at the time until I talked to some instructors at other dive shops and was told that was nuts.
By the way, max depth last dive was 49 feet, and was using a rented AL80 tank.
.

Yep. Sounds like you were underweight. I wouldn't bother with a pound, I'd try 1.5 or 2 lbs. You're not diving deep or bad water, I doubt that the extra 1/2 to 1 pound (if 2 is a little over) will make any difference. You'll be a lot more comfortable in the water 1 pound over than 1 pound under! When your dialing in for a pound, you are getting down to splitting hairs, honestly. Others will swear that a pound makes a huge difference, but

I sink. I cannot float even with full lungs, though I am plenty fluffy!
consequently, I don't need as much weight. It doesn't mean that I am a better diver than someone that needs more, it just means that I am different. Don't be pressured into the stupid idea that the really good divers use less weight. Really good divers have very little or no EXCESS weight. I know what I need and if I trim a pound or 2 off the weight belt, I'll need some rocks before the dive is over!

If this is helpful, give it a "like"!

 

[Adventure-Ocean]

Bouyancy is a fascinating aspect of diving. There are many factors to consider and some will change as you use the air. It took me quite a while to find my perfect weight. I have to weight myself different when I used my shortie wetsuite (warm saltwater) instead of my full one. Freshwater and saltwater require different weight to be used as well. We used to dive with the old steel 72's and had more adjustments to weight when we started with aluminum 80's. You are right on when it comes to breathing. When we were required to do a work related project underwater, we'd have to weight ourselves a bit more because we required more frequent and fuller breaths. Adjusting your personal equipment to fit and be comfortable and function well is part of owning your own gear. Once everything is set for you it's easier to relax and enjoy the dive. You sound like a smart person and it's great you are willing to share your questions. I don't know if there were many diving forums in the 70's but I would have loved to tap the wealth of knowledge being shared here at Scubaboard. Adventure-Ocean

 

[Peter69_56]

Ok, to put a different slant onto this thread.

I am new to dry suit diving. Just bought one and went to do a pier test dive. I found with twin independents 12 litre steels I needed 35 lb when they were empty to descend. Yes I did make sure I purged the suit prior to getting into the water and ensured I had the suit empty when near under the water, also the wing was empty and I breathed all the way out.

With twin manifolded 12 litre steels the weight is about 26 lb, with independents its about 35 lb (manifold is 4 kg (9 lb) extra).

For those who dive dry suit and twin steels, is this about the ballpark figure to start? I am 90 kg (198lb)

I have spoken to a number of divers and they all seem to not carry as much weight, but it appears they don't worry about ensuring they can descend on near empty tanks. I have always set myself up on near empty tanks so I am nearly buoyant and found this works ok.

To carry 35 lb I have had to buy a harness as a weight belt alone is just not suitable.

So I suppose my questions I would like people to respond to are;

What weight do you dive with using twin cylinders 12 litre (or cylinder size) (manifold/independent) and a dry suit, and what do you weigh?

How do you set up your weight if its significant?

Do you set your weight to be near buoyant with no air, or do you just assume you need a bit less weight as you will never use all your air (it appears many people do this to justify carrying less weight)?

 

[RJP]

What weight do you dive with using twin cylinders 12 litre (or cylinder size) (manifold/independent) and a dry suit, and what do you weigh?

How do you set up your weight if its significant?

Do you set your weight to be near buoyant with no air, or do you just assume you need a bit less weight as you will never use all your air (it appears many people do this to justify carrying less weight)?

Questions - what kind of drysuit are you diving? What kind of undergarments are you wearing? Is your 35lb weight including backplate? How tall are you? Where on earth have you found a manifold that weighs 9 lbs! Is it made out of depleted uranium?

I dive manifolded steel 119cf steel cylinders with an AL backplate and zero additional lead. I weigh 180lbs at 6'2" and dive a trilam drysuit with average loft undergarments.

 

[Peter69_56]

Questions - what kind of drysuit are you diving? What kind of undergarments are you wearing? Is your 35lb weight including backplate? How tall are you? Where on earth have you found a manifold that weighs 9 lbs! Is it made out of depleted uranium?

I dive manifolded steel 119cf steel cylinders with an AL backplate and zero additional lead. I weigh 180lbs at 6'2" and dive a trilam drysuit with average loft undergarments.

Ok dry suit is a waterproof hybrid. It has a special filler inside to keep you off the suit wall (this is part of the issue)
Aluminium backplate (due to travel)
Had a thin thermo garment on only
35 lb was lead only
I am 6'
The manifold is on a set of twin faber 12.2 litre steels with stainless bands. The independents have valves and cambands so its the weight of manifold and bands.

I am sure I could descend with no weight, but with minimal air I would be a cork

 

[Corky Leadhogger]

Instructor started me with 12 lbs and was very reluctant to give me more. But I am a lardass and float like a cork in warm saltwater. Just could not get down with a dumped BC and empty lungs while kicking.