Weight and Trim help

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scoobajay

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Hey y’all. After a few years’ diving hiatus, I returned with quite a bit of buoyancy and trim issues. Wondering if anyone has suggestions…

I’m 5’7 female, 120 lbs. diving in warm waters with 1mil to 3 mil shorties. AL80 usually (though this trip I toggled between this and an AL63, I think). Integrated weight with 2 pounds in each pocket (total of 4). If I add more weight (6 pounds) I have to keep some air in my bc for much of the dive, but if I go with 4 pounds I get too light toward the end of the dive.

Which is better, a little too heavy or a little too light? Or does having to keep air on your bc not actually mean you’re too heavy? Also, I tend to barrel roll throughout the dive, even if I continuously “straighten out” the little air in my bc. What’s that about?
 

Bob DBF

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A bit heavier is better than light, as you don't want to surface inadvertently.

There is less than 2# difference in buoyancy between an 80 and a 63. I would weight properly for an 80 and use that on the 63.

To check for proper weighting, at the end of the dive at 15' and 500# left in the tank, with an empty BC, you should be neutrally buoyant.

The barrel roll sounds like your weight is too high, and in combination with the weight of the tank is rolling you over. If you wear a weight belt, put the weight towards the buckle to offset the tank. The BC is trapping air, but its something I'd have to see because I haven't used a jacket BC in decades.
 

ibj40

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I’d also suggest adding a couple of weight pockets to your tank strap to contribute to balance of center of gravity.
 

Rukkian

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Hey y’all. After a few years’ diving hiatus, I returned with quite a bit of buoyancy and trim issues. Wondering if anyone has suggestions…

I’m 5’7 female, 120 lbs. diving in warm waters with 1mil to 3 mil shorties. AL80 usually (though this trip I toggled between this and an AL63, I think). Integrated weight with 2 pounds in each pocket (total of 4). If I add more weight (6 pounds) I have to keep some air in my bc for much of the dive, but if I go with 4 pounds I get too light toward the end of the dive.

Which is better, a little too heavy or a little too light? Or does having to keep air on your bc not actually mean you’re too heavy? Also, I tend to barrel roll throughout the dive, even if I continuously “straighten out” the little air in my bc. What’s that about?
The barrel roll really sounds like your tank is making you back heavy, and you are probably using a jacket style instead of back inflate, so you have some added buoyancy in front. Adding a couple more pounds in front should help counteract that. Sometimes getting trim can mean over weighting a bit depending on your config. With my ss bp/w when I did my rescue class, I went with no thermal protection in the pool, and was over weighted with just the bp/w, but still needed to add a bit of weight to the tank band to help me float while doing our surface drills.

As others said, you should be a bit negative (around 4#) to start the dive, as that is the difference between empty and full of a standard al80. At the end of the dive, you want to be neutral at 15' with 500 psi left in the tank. This will mean you need to counteract some of the additional weight at the beginning of the dive.
 

johndiver999

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Being two pounds heavy is not a problem.

Keeping all your weight (only 4-6 lbs) on your belly hanging below you, will be the best thing you can do for stability and offsetting a roll. it might not be the best for trim (tipping forward and back), but to me, rolling is more distracting.

For an initial attempt, a weightbelt might be the quickest and easiest thing to try.
 
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