"floaty" feet and lead-head....is it my tank?

[MXGratefulDiver]

I'm not a big fan of ankle weights, as I think they tend to get overused ... but they are a legitimate help for some (rare) people.

Also, are you sure you're not just underweighted, and tipping head down to maintain your position in the water? Have you done a weight check with only reserves in your tank?

Another thought ... what kind of fins are you using? Some fins are positively buoyant. If your fins float without you in them, consider exchanging them for a heavier, rubber fin like a Jet or F1.

... Bob (Grateful Diver)

 

[RJP]

By the op i would think that as the dive ends and the tank empties he should become head light and not head heavy.

Drop an empty tank in the water and see which way it orients itself...

An empty tank is "head heavy" due to the tank neck, valve, and reg being on that end.

 

[tbone1004]

That's true on an aluminum tank, but not so much on a steel. To get your head up on a steel, slide the tank down. Even when empty, the entire steel tank is negative so you are simply shifting the load on a fulcrum. To get your head up on an AL, slide the tank up. On an AL, the butt is buoyant and pulls your backside up with it. By moving it up, you are reducing the lever arm affect of the buoyant butt (moment of inertia) by shifting the AL tank forward.

One of the ways I get my student's feet up while in the Scuba position is to push their AL tank all the way down. We work from that position to get them horizontal.

They are net negative, but that doesn't mean that the bottom of them is negative, just means overall they are negative. Most of the fabers are VERY floaty in the bottom end which is why they will stand up on end when they are empty. That only happens because the bottoms are negative, and actually most steel tanks are like that. They are typically 1 to 1.3lbs negative when empty WITH the valve, and as a valve weighs somewhere along the lines of 1-2lbs, the tank itself is floating but the valve is keeping it down. Exceptions are medium pressures, and some of the PST LP's like the 104's.

 

[rhwestfall]

HP80's just give me fits because of all the weight being in such a small area up front.....

 

[Searcaigh]

You could also strap a weight to the bottom of your tank using a cam band to keep your lower half down.

If you only slowly come out of trim you might only need a pound or two down toward the bottom of the tank.

+1

Although I only need this for AL80s, this may be your solution

 

[The Chairman]

When I side mount AL80's, I put 4 pounds of weight near the bottom using a Cam strap and some bungee to compensate for the floaty butts. I've actually done that with one student on their back mount AL80 to get them in trim.

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I worry about weight swing when I am establishing neutral buoyancy. It doesn't seem to affect trim much at all. Sliding tanks back and forth are my primary methods of establishing trim. I'll use ankle weights after that... just not on ankles. They are great on tank necks to give additional head weight.

Here's a good exercise when you think you are getting your trim close. Establish your neutral buoyancy about a foot off the bottom. Once you feel in control, close your eyes for 10 seconds. How is your attitude? What do you need to adjust? Make the adjustments and try again. Once you can manage 10 seconds, go for 20, 30 and even 60 seconds.

BTW, if you're using your hands at all, you haven't established neutral buoyancy.

 

[DeepSeaExplorer]

I have seen someone take a V weight, cut it in half, and just use the lower half. V-weights are larger on the lower end for a reason. Modifying it is a good option if you don't need the full 11lbs.

For years, I put a 2lb weight between the bolt and lower band. I cut open a weight with a hacksaw and drilled a hole thru it for the bolt. It was fantastic, but wouldn't work with more than 2lbs due to the physical dimensions.

Steel 80s are short tanks. I have 104s and 98s and I notice the difference when I switch between them. (I just sold the 98s.) If you're trying to switch between 100s and 80s that may be your problem. I tried adjusting the harness somewhere in between, which took probably a dozen dives. I got it close, but it never was perfect. You might have to decide between a harness that's not optimized for either or rethink the tank situation.

 

[crabbyfiddler]

Change to a heavier fin perhaps? Worked for me. Also redistributing weight slightly lower on the torso.

 

[mruseless]

Have you confirmed on video that you are truly head-down? I know that personally if I feel like I'm flat, I'm actually hovering at about a 30 degree angle, and when I'm truly horizontal in the water it feels like I'm head down.

 

[porkpiehat]

I had the BC made years custom under the advisement of a friend before I knew much of anything. Made by Manta, I think it's a standard 6lb steel plate and a 30 or 40 lbs wing? We've already moved the wing up as far as possible. My LDS is pretty good with all this so I think he's optimized the plate/wing to be the least tippy it can be.

I moved to heavy Hollis f1 fins last year. They help a bit and they are super maneuverable in wrecks and tight quarters. I'd say the waist strap fits a little bit above or at my navel. We are in New England so I'm wearing socks under my boots now and that might offset the negative bouyancy of the f1's.

I think read another thread that rings true to me...My hood is built-in (one-piece semi-dry) and doesn't fit super tight. I wonder if exhaled air is traveling down my neck and accumulating towards the bottom of my suit?



In terms of technique and all, I am pretty confident in my form. If I let myself relax at the end of the dive I will ultimately be vertical.

Thanks for all the suggestions so far! It's good to know I'm not crazy.