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Buoyancy Aluminum to steel
CrazyJones - 3/29/2017 1:01 AM
Category: General
Replies: 12

I got my new faber steel today.

So if I’m currently neutral with my aluminum 80 which weights 39.6 lbs (full on land)
And my new HP100 steel weights 45.8 (full on land)

I can dump 6 pounds out of my BC weights and be in the ballpark. Is that right?

JeffNColdWater - 3/29/2017 2:05 AM
That’s about right. I used the divebuddy calculator and it told me to dump 5 +/- and 6.5 was dead on for me. You’ll really notice the need for less weight at the end of the dive when you get close to empty.
LatitudeAdjustment - 3/29/2017 8:05 AM
Ditto, I took off 6 pounds also.

If I’m diving steel with my 3 mil and my cold water BP&W which weighs 6 pounds I was left with no ditchable weight :( I had to go with a plastic BP which is better for travel anyhow.
Eric_R - 3/29/2017 10:07 AM
Looks correct in my calc’s.
CrazyJones - 3/29/2017 3:39 PM
Thanks fellers. I was just wondering since I was always told steel tanks are lighter than aluminum, but that isn’t the case since I’m using HP instead of LP. My tank is actually 6 pounds heavier than the aluminum one.

I can go from 22 pounds to 16 and make minor adjustments from there.

Next question...I currently have 8 lbs in each BC front weight pocket. And I have 3 lbs in each rear trim pouch. Is it predictable to say if I should remove the trim weight (rear) or reduce the BC pocket weight (front) instead. Or is that something I’ll just have to try and find out? Or is it "doesn’t matter"?
daz88 - 3/29/2017 4:15 PM
you should just be able to lose the trim weights, but just try it each way and see what feels better in the water to you.

"I was always told steel tanks are lighter than aluminum".....different tanks have different weights, and all different sizes.
JeffNColdWater - 3/29/2017 7:29 PM
From BenDavid: should remove the trim weight (rear) or reduce the BC pocket weight (front) instead

That’s going to be a personal fit based on your body, rig, buoyancy control and a few other conditions. I dive in very cold water with a 7mm suit and keep almost 30% of my weight (regardless of tank) in my back trim pockets. When I dive in mild climates I use 15-20% of my total weight in back if I have a 3mm or shorty on. If I’m in the tropics with a dive skin or just trunks and a t-shirt, I don’t use trim weights.
LatitudeAdjustment - 3/29/2017 8:37 PM
From BenDavid: I was always told steel tanks are lighter than aluminum,

It’s not the starting weight you need to worry about, at 500 psi a steel tank will sink, an aluminum tank will float. That’s where the 6 pound difference shows up.

Also keep that in mind if you take off your BC in the water before boarding the boat.
CrazyJones - 3/29/2017 8:52 PM
From LatitudeAdjustment: Also keep that in mind if you take off your BC in the water before boarding the boat.

So if I take off my BC to board the boat witht he steel then my stuff will sink? I don’t know if the charter boat would like me taking off my BC to board the boat but I’ve done it on my own boat when diving and my rig with the aluminum 80 would just float.

Thanks for the reminder. I woulda probably not thunk it out and found out the hard way. LOL
CrazyJones - 4/01/2017 10:47 PM
I was searching around trying to figure out why my HP steel 100 weights 46 pounds (with boot valve and air) but the various sites say it weighs about 34. Then I noticed the weight the manufacturer states is without boot and valve, which’d add some pounds. But some where I read said the air would weigh about 8 pounds. Is that right? I’m surprised to learn that air weighs so much.

I haven’t had a chance to empty my tank and compare it to full and actually see if the air weighs 8 pounds. Anyone know?

My steel weights 46 with valve boot and air and my AL80 weights 40 with valve boot and air. (rounded)
CrazyJones - 4/01/2017 11:12 PM
I guess it does. Apparently air weights 0.0807 lbs per cubic foot. So x100 would be 8.07 lbs.

You just never realize air actually weighs something,
I guess. It is supposed to be "light as air" LOL