Lead weight with steel vs Al tanks concerns

[adiverslife]

If you feel you need a steel tank and you are this frustrated about how much weight to carry I think you need to take a peak performance buoyancy class. This is something that should be included in you open water or advanced open water class - a huge hole in PADI's training. This would help solve a number of things. 1 why you feel you need an HP100? Are you going through air that quickly? 2 This is the big one. Your primary buoyancy compensation device once you are balanced is your lungs. I agree with the last person posting about not staying ion the surface with a full HP 80. I am not saying this to be a jerk but having someone work with you hands on in a peak performance buoyancy will help you:

- use less air as you will be working less
- reduce the weight on your back.
- Make it easier to get in and out of the water
- increase your bottom time.

If you were diving in a dry suit in cold conditions there is definitely a value in a steel tank as it reduces the weight you are carrying in your lower back. Another consideration would be a steel back plate. That gives you 5.5 pounds to compensate for aluminum tanks. I live in Bonaire and do a lot of underwater cinematography and coral treatment. My buoyance is exceptional. I wear a skin, am diving in 78 degree water right now and I wear 1 pound of lead. I am not skinny. I just have a lot of time underwater and use my lungs to control most of my buoyancy.

We could take a lot of time discussing this but I think having a peak buoyancy class with someone who is very knowledgeable would be your best solution now. I have friends that come visit us. I spend 2 dives teaching peak buoyancy tailored to them and I have doubled or tripled their dive time and reduced the weight the carry.

Just a thought. I have been diving 37 years. I hope this was of some help to you.

 

[jfw432]

@adiverslife I agree and I'm certainly not the best but I generally have pretty good buoyancy. I'm sure I'd learn from a peak buoyancy class but I'm focused on different things right now. That said, I am going down this road to better accommodate and match my wife. I'm experimenting, optimizing, and trying to learn what I can while out of the water. I'm 200lbs and 6' tall while my wife is 96lbs and 5'2".

My goals are two fold...
1. I saw a potential opportunity to reduce the amount of weight she has to carry with a smaller tank that better fits her back. Her buoyancy is going to be different than mine but she typically uses less weight than me so I had some concerns if I'm using little to no weight. I don't want to put her in a dangerous position so just wanted to ask.
2. The thoughts of an HP100 for me is to better match her consumption. My crudely calculated consumption rate is around 0.5-0.6 cuft/min in spring water so it could be better but I don't think I'm really sucking my tank down. I have an AI computer this weekend so I'll get a chance to see where my consumption truly is with depth changes factored in.

 

[jfw432]

I got to play with weights a lot more this weekend. With the AL80, I can get under the water with 7lbs of weight if the suit is dry and I let all air out of lungs and give it a little oomph with my arms but decided to add an extra pound to make it a little easier to get down and to prevent accidental runaway at depths above 10ft. Meanwhile, with no weight and the HP80 steel tank at 650psi, I would still sink at the surface with a full lung of air. The math doesn't seem to add up but that's what I'm actually getting. I also noticed that the HP80 had the highest SAC rate but could be coincidence. The last dive had a pretty high SAC rate as well but I was moving around a lot trying to get videos and photos of friends so it's not a fair comparison.

I may do a little more tinkering when I get the chance and I'll probably have my wife try the steel tank and see what she thinks but I feel like the AL80 is going to be my tank especially in warm water unless I change to a thicker suit. It's kind of too bad though because the dry land weight of the steel tank is so much nicer to walk around with but then I get in the water and it feels like a brick. I think if I get a solid fill on the AL80 and actually use the whole tank, it's going to be a decent amount of time underwater and my wife may get cold before we're actually out of air too. That may change on a sweet wreck or reef though.

 

[inquis]

With the AL80, I can get under the water with 7lbs of weight if the suit is dry and I let all air out of lungs and give it a little oomph with my arms

Was that at the beginning of the dive? If so, you'll have an issue after breathing the tank down and becoming 5 lbs more buoyant.

 

[jfw432]

Was that at the beginning of the dive? If so, you'll have an issue after breathing the tank down and becoming 5 lbs more buoyant.

Yes but that was with 2300psi in the tank. I didn't really have any issues at the safety stop with 800psi but I didn't really kick up the last 3-4 ft although I can't recall if my BCD was fully deflated at the time. I guess if I had a full 2700-3000psi, it would've been easier to go down and if I came up with less than 500psi, it might be hard to stay down above 10 ft. I guess 1-2lbs overweight is better than 1-2 underweight.

 

[Pavao]

Not always. If you have a 8 mm wetsuit plus a 2 mm vest when it is cold and you go quite deep, you might not be able to swim up from depth with no air in your BCD but still have a balanced rig (quite neutral at the safety stop with no air in your BCD). It can also happen with less thickness with your suit...

That’s actually an imbalanced rig you are describing.

Balance comes from finding the sweet spot between NOT TOO heavy at max depth and NOT TOO light at safety stop depth.

In case of BC failure at max depth and start of dive, full weight of the gas on your tanks, you want to be able to swim up by your own power, kicking up. And be able to hold a stop near the surface for safety stop/deco with nearly empty tanks, when you’ll be at lightest point.

This is the reason those of us who dive balanced rigs don’t usually use wetsuits thicker than 5mm (plus a vest), the suit compression gives too much imbalance between max depth and surface. If you’re overweighted at the bottom due to suit compression and can’t swim up, a backup means of buoyancy is needed. We do find ourselves in such situations when bigger tanks are needed for deeper dives, say, steel tanks are used and that brings an imbalance to this equation, something then needs to change, outgoes the wetsuit and Drysuit becomes the alternative, to add the back up means of achieving positive buoyancy.