More air......last thread

[jwlast]

Thanks to all with the help on the "More Air......" posts. I bought a 100 cu ft aluminum tank. Now to round out the equation.....how will it effect my bouyancy (both full and as the air gets used up) and how much weight I should be carrying?

To date, when using the 80 cu ft steel tank I've been diving with 22 lbs of weight. I'm using a 3 mm full wet suit and as the tank empties I feel overly bouyant anytime I get with 10ish feet of the surface (I don't know if any of that makes any difference). Come to think of it, I've been having minor problems starting down at the beginning of dives also...but just minor.

Any suggestions on what to do with increasing or decreasing weight moving from an 80 cu ft steel tank to a 100 cu ft aluminum tank would be greatfully appreciated.

JT

 

[O-ring]

From what I remember, AL100s don't swing as positive as AL80s. The Catalina 100s start off more negative than their 80cf siblings and swing to around neutral (if I remember right). The Luxfer 100s swing more positive than the Cats, but still less than an 80. Regardless, you will be heavier at the start with the heavier tank and more gas so you may find getting down easier.

 

[lucid]

I am not trying to flame anyone here so dont jump on me. But how the heck can you need 22 pounds of weight with a 3MM full and a steel 80? I wear 12 pounds with double aluminum 80's and a drysuit. No weight when diving a single steel and my wetsuits. I read this stuff a lot about people that use 20-30 pounds of weight when diving wet with a single cylinder. What gives?

 

[jwlast]

22 lbs? Well I'm new to this, but that's what I use and still feel positively bouyant. 3mm full wetsuit, salt water, 6 ft, 210 lbs, 80 cu ft steel tank are my starting parameters. I wish I only had to use 12 lbs, sure would be easier to luge the stuff down to the beach to get into the water.......

JT

 

[O-ring]

jwlast once bubbled...
22 lbs? Well I'm new to this, but that's what I use and still feel positively bouyant. 3mm full wetsuit, salt water, 6 ft, 210 lbs, 80 cu ft steel tank are my starting parameters. I wish I only had to use 12 lbs, sure would be easier to luge the stuff down to the beach to get into the water.......

JT

Man, I read that wrong! I thought you meant an AL80 not a steel 80! I would try your current weighting anyway...if it is an HP80 you are diving now, you may actually have to add some weight for the AL100. Do you know who makes your AL100?

 

[Scubamedicjoe]

I am not trying to flame anyone here so dont jump on me. But how the heck can you need 22 pounds of weight with a 3MM full and a steel 80? I wear 12 pounds with double aluminum 80's and a drysuit. No weight when diving a single steel and my wetsuits. I read this stuff a lot about people that use 20-30 pounds of weight when diving wet with a single cylinder. What gives?

Lucid you are wrong!!!! And you are flaming him!!!!
Some people even though (I feel thats too much weight for me).
Everyone's body is different some have more fat and higher body percent then others that increase the weight needed to be used.
There are many factors that require different people to have that much weight different suits / size of suit / thickness of suit/ and also the newness of the suit. But of course I hope you took all these things into consideration, just to let you know I too feel that’s allot of weight but each and every person must use the weight for them.
The best class anyone could take is
Advance buoyancy control class. This their they learn weight control and best of all how to control them self’s and save our coral. Sorry don’t mean to jump just you others in this sight need to take this into account too!!!!

 

[Scubaroo]

A 100cf Luxfer 3300psi aluminum tank will swing from -3.9 to +3.5 during the dive. If you don't know the stats of the steel tank you were diving, assume it is neutral empty (most steelies are either slightly negative or neutral when empty, although there are some exceptions), so add about 4 pounds if it is a luxfer.

A Catalina 3300psi aluminum tank will swing from about -7.5 to 0 (neutral), although the table I got that from is known to contain errors. So start off with the same weight as you usually use, and see if you can maintain a safety stop near the end of your dive.

So look at your tank and see which brand it is.

Don't feel badly about your weight - when I started diving I needed 35lb to stay down in a 3mm shorty - I'm down to 12lb in a drysuit now.

 

[lucid]

How the hell is that flaming? I explained what I used and then explained that I didn't understand why others had to wear so much weight. Then I ended it by saying "What gives?", which may be poorly worded but it is a question. I never said he was doing anything wrong. I simply stated that I didn't understand. I have often wondered if people wear that much weight because they actually need it or because they have been trained to wear that much weight.

I think you need to look at some non-ditchable weights if you are actually strapping that much weight to yourself with a belt. How can it be safe? What happens if your belt slips while your on the bottom? Could you hold a 30 min deco stop at 20 feet if your 30 pound belt slid off? I am not saying that I know the answers to any of those questions and I may be totally off. I am just asking.

/me envisions a submarine launching out of the water after blowing all tanks.

 

[raybo]

22 lbs? Well I'm new to this, but that's what I use and still feel positively bouyant. 3mm full wetsuit, salt water, 6 ft, 210 lbs, 80 cu ft steel tank are my starting parameters. I wish I only had to use 12 lbs, sure would be easier to luge the stuff down to the beach to get into the water.......

to see if you BC isn't completely deflating or something.

Your weighting will almost cetrtainly come done.

You're about the same size as me. I dive Al80 in a 7mil neoprene dry. Started at 26# (in fresh water) when I fisrt got it early last fall. As I learned to handle it, I've slowly been dorpping how much I need.

Scubaroo once bubbled....

Don't feel badly about your weight - when I started diving I needed 35lb to stay down in a 3mm shorty - I'm down to 12lb in a drysuit now.

With BP/Wing? Shell? Curious as much as anything. I'll never that low with mine.

When I first dove my 3mil FJ/shorty, started at 16-18, and after a week of 2 tank/day vacation, I was down to 10-12. Stay at it, it'll come around.

Don't know about anyone else, but my air consumption went way down when I got the wieghting under contol. Having the same thing with relearning the dry.

 

[Scubaroo]

raybo once bubbled...
With BP/Wing? Shell? Curious as much as anything. I'll never that low with mine.

Yes and yes, with 300 Polartec undies. Actually it was a typo - I'm down to 10lb.

Part of the point is, that someone else's weight requirements is not comparable to other people's weight requirements. My particular combination of backplate, STA and LP steel tank would require me to add about 14 pounds just to switch to a jacket BC and aluminum tank. So my 10 with that 14 would put me at someone else's 24 pounds - gear configuration choices have as much to do with the net amount of lead required to balance your rig as bodyfat and exposure protection.

I would probably have to add a couple of pounds of lead to dive a vacation rig!