How will my weight loss affect weights needed?

[Ron G.]

I've recently lost about 20# (which is a good thing) and am getting ready for a dive trip.

I've been using 12# weights for some time and am trying to anticipate what to expect now.

I'm guessing I might need a little less weight (1-2#). Does that sound right?

Also, I won't be at a place where I can tinker with my weighting on a shore dive. Right now, my plan is to go out on our first boat dive with my regular 12#, then check my buoyancy near the end of the dive to figure out how much weight (if any) I should reduce.

Any thoughts?

Thx.

Ron

 

[Oldbear]

Ron,

Congratulations on losing the weight...that has to make yo feel good.

Yes you should use less weight, assuming you lost more fat than muscle mass. I would try and do a weight check even before your first boat dive. One or two pounds might be enough or you might be pleasantly surprised and can drop even more weight.

You lost the hard weight, now reward yourself and dive with less lead

 

[TheRealScubaSteve]

I'd think you'd be safe dropping 1-2 lbs, but only a weight check will be able to tell you that for sure. Try out a weight calculator - Estimated Diving Weight Calculator. I plugged in my current weight and weight - 20 pounds with a bathing suit and got the same lead figure. With exposure protection it dropped 2 pounds. It's accurate within 2-3 pounds of my diving.

 

[DivemasterDennis]

How much less weight you will use ( and you will use less) will depend in part on the percent of weight loss you have achieved. If your were 200 and are now 180, you will drop more weight than if you were at 280 and are now and 260, and so on. Do a weight check for sure.
DivemasterDennis

 

[Steve_C]

I did a caculation a while back. The specific gravity of fat varies, around 0.85. So taking an average spg and assuming that fat was incompressible and assuming that a fat loss reduced the total volume that your body displaced by the volumne of the lost fat, it came out to about 1 pound of lead for each 10 pounds of fat.

Muscle spg is close to 1.0 so muscle loss is no difference.

In a worse case scenario you might only have 200-300 psi in your tank. So if I am doing a weight check I do it at 300 psi.

 

[redacted]

How much less weight you will use ( and you will use less) will depend in part on the percent of weight loss you have achieved. If your were 200 and are now 180, you will drop more weight than if you were at 280 and are now and 260, and so on. Do a weight check for sure.
DivemasterDennis

How do you figure that????

Density of fat is .9. Density of muscle is 1.06.

If the 20# were all fat, the buoyancy change should be 2#. I'd drop 1# and check.

 

[Ron G.]

The 20# I lost was from a starting point of 210#.

I tried the Diving Weight Calculator linked by TheRealScubaSteve and it does indicate a change of about 2#, but I'm skeptical because it significantly over-estimates what I should have been using at my old weight. I was 210, wearing a 3 mil wetsuit in salt water, and it indicates about 19# weights. I've always used 12#.

Having said that, if a buoyancy test did show that I should drop 1#, to 11#, do you put 5 on one side and 6 on the other? Would that cause a tendency to roll toward the heavy side, or is that too small a difference to matter?

thx.

Ron

 

[EFX]

The rolling force will depend on how far out the weights are from the center line of your body. I use an XL ScubaPro Nighthawk and have not noticed any appreciable force with a 2 lb difference. I would drop 2 lb and go from there. Bring a 1 lb weight with you as all the charters I've been on don't have 1 lb weights.

 

[Lostdiver71]

It overestimated my weight by 4 pounds.

 

[Steve_C]

Your total weight includes things like bone and muscle. When I was young I was not buoyant in fresh water unless my lungs were completely inflated. Floating was always the hardest thing for me. On the other hand I often got to play victim when testing life gaurds. One puff and they were hauling a nonbuoyant dead weight.