Help Me Solve My Weighty Problem

[DiveDaddyDale]

I stand corrected about the volume of air in each tank, and the note that the HP100 is not stainless steel. The bp is, but not the tank...thank you.
All comments appreciated.

Let me pose this question, why do I see so many tech divers using oh steel tanks! There must be a reason they prefer the steel over the aluminum.

Also appreciate the advice to relax and dive more. This is quite obviously a first step. I will probably increase my wing to the Hollis 38lb to give me a little more lift, but not decided about keeping the SS bp or going back to a lighter weight plate. Travel weight is not a concern for me as my career seldom allows me to have more than 2 days off in a row ��.

This question would probably receive some interesting comments if posted in the DIR/Tech forum. If I knew how to move it, I would.

Thank you all very much for your comments and advice.

 

[Capt.Gene]

I wonder if your plate wing and tank are riding high on your torso instead of being anchored low on your hips.
You don't mention it but tall and thin divers often fight their gear placement.

 

[kmurray719]

You will probably find most tech divers in drysuits....which require wearing more weight than your thin wetsuit. Steel tanks generally remain negatively buoyant (or neutral) when empty. AL tanks become +, which requires carrying weight to compensate for that. A lot of people prefer steel tanks with a drysuit or thick wetsuit to minimize the amount of lead they need to use.

 

[gizmo1972]

aluminum tanks when low on air become positivly bouyant steel tanks stay the same so tech divers prefure this for weighting

 

[Jim Lapenta]

I like steels because they have better buoyancy characteristics for the diving I do. They also do not present the problems at fill time that some aluminums do. Especially once they get some age on them. Due to serious misunderstandings of the facts some shops will not fill al tanks more than 15 years old. Two places near me won't even hydro them if made before 1990 - 95. Even though it was only the one alloy that was bad. But they have no problem doing my steel LP72's from 1953 and 1955.

What I am going to suggest is that you get a wing in the 30-32 lb lift range, use the SS plate with aluminum tanks, and the kydex with steels. Then stop monkeying around with it for the next 50 - 75 dives. Just dive them. Do a proper weight check first in just your wet suits with mask, snorkel, and fins. Weight yourself so you just start to descend slowly when you exhale. Make a note of how much that is with each suit.

Then determine the weight of your rigs by weighing them in the water with a fish or luggage scale. Set them in the water and see how negative or positive they are with a tank on them and the wing deflated. Then adjust the weight on your belt if necessary.

Once you have done that get another 15 or twenty dives like that and see if an adjustment needs to be made. Don't do one dive and make a change unless you are grossly over or under weighted. And when you do make an adjustment do no more than a pound or two.

If your number of dives is correct you're not yet at the point to go making big changes on a moments notice. That takes time and experience. I can pretty much take a rig now and any type of suit and decide what I'll need to start with. Then by the second dive make all the necessary changes if required.

But that ability has been developed over more than 500 dives and perhaps 300 hours in the pool where much was practicing proper weighting and teaching people how to do it.

What I am afraid of is that you are making too many changes too fast and setting yourself up for frustration. Slow down, relax, take your time. And save your money. You'll get there. Just take it slow and enjoy the learning experience.

 

[GrumpyOldGuy]

aluminum tanks when low on air become positivly bouyant steel tanks stay the same so tech divers prefure this for weighting

Wrong! Steel tanks have the same change in buoyancy per cu/ft of air that aluminum have. You cannot change the laws of physics.

Steel is denser and stronger than aluminum, the side walls are thinner resulting is less displaced water. So the tank weight can replace some of the ballast weight needed to compensate for the exposure suit. Since tech / cold water divers need significant exposure protection and tend to need more air, the weight savings is significant. In warm water, its not.

 

[tech3324]

Wrong! Steel tanks have the same change in buoyancy per cu/ft of air that aluminum have. You cannot change the laws of physics.

Well said. That's an often misunderstood fact. The change in buoyancy can only be due to air consumption, not the tank material.

 

[guruboy]

I use a buoyancy tank to trim my twin 50's. I wear them valves-down and weight makes me feel off balance, The tank is a 12 inch piece of 4 inch PVC pipe with clear lexan end caps so that I can check for water leaking in. It is mounted low near the valves. I added lead to my weight belt to compensate. Now my rig, and me in my wetsuit, are closer to neutral.

That's a neat idea. Instead of adding weight to fix trim, you add lift.

 

[DiveDaddyDale]

Very sound advice noted above Jim.
Reasoning is sound regarding changes in tank buoyancy relative to tank material.
I agree that a good set up would be to have a SS bp/w rig for the AL80 and a lightweight plate/wing for the HP100. I was hoping to avoid having to set up 2 HOG rigs...sigh. But that is the strongest solution to the puzzle.

Lots of experimenting to come as I follow Jim's general guidelines. If you happen to be interested in knowing how its going, just PM me.

Thanks so much

 

[bj139]

Tank -11 + BP -7 + Reg -2 + Head -10 = 30
You need a 30 lb wing. 32 seems to be a common size, which will be enough for your 3mm but may not be enough with your 5mm. Extra lift will not hurt you at all. It is a safety margin with minimal extra drag. You could go smaller since your wetsuit provides about 7 lbs lift but compresses at depth so gives less lift there. Your buddies are right suggesting a 38 lb wing. You will not notice the extra lift until you need it then you you will be glad it's there. I use a 40 lb wing with a HP117. Not being able to float on the surface is dangerous as well as not being able to get neutrally buoyant at depth.