Soft weights write up (with pictures)

[elmer fudd]

I've used a few improvised weights now. At one point I just slipped steel barbell plates into the weight pockets of my BC. That worked OK, but they weren't shaped right, were ridged, bulky and rusted. Then I bought 25 lbs of reclaimed lead shot at Sportco and created 2 lead weights by pouring it into a pair of old socks, zip tying the ends and putting those in my weight pouches. The downside of that was that they were dirty, they never seemed to dry and they were bulky.

Currently, I dive with 6 solid 4 lb lead weights and it's the best system I've used yet. They're clean, compact, they dry quickly and since I have a few 2 lb. weights as well, I can quickly and easily readjust my weight for different tanks or undergarments.

One thing to keep in mind about shot based weights is the bulkiness created by the dead space between the shot. Lead is just over 11 times denser than water, so that 4.18 lbs. of water you used to displace the air could be occupied by 47 lbs. of lead. So your weights will be nearly twice the size of solid weights.

 

[FrogManMike]

a you might try a shot blasting company for lead shot

 

[Nitrodiverrr]

If you use "dirty" lead shot just wash it first. Put the shot in a sturdy pail with a good amount of water and dish washing detergent and mix for awhile. Nylon mosquito netting sewn into pouches with nylon thread make for very flexible bags that dry well. By folding the netting into quarters you will get a double thickness of material and only have to sew three sides.

 

[skynscuba]

I've been thinking about "soft" weights myself, but along the lines of fabric pouches and stainless steel ball bearings instead of "dirty" lead shot.

The downside of that, along with cost, is that they will be bulky -- about 52% larger in volume than lead for the same underwater buoyancy. If tungsten weren't so expensive, I'd be using that to reduce volume (same goes for gold and platinum!).

 

[FrogManMike]

I make weight bags out of thick mil plastic that will fit in my weight pockets and fill them with wet sand that I weigh out on my digital scales the water causes the sand to keep its shape inside the bag plus adds a little weight.
excellent material for ballast and the best part it is free.

 

[skynscuba]

I make weight bags out of thick mil plastic that will fit in my weight pockets and fill them with wet sand that I weigh out on my digital scales the water causes the sand to keep its shape inside the bag plus adds a little weight.
excellent material for ballast and the best part it is free.

Sand is not so practical for this application. It only had a specific gravity in the 1.9 range, vs. 11.3 for lead. You would have to be carrying ~19.2 pounds of sand to get the same change in buoyancy in the water as you get with 10 pounds of lead, and it would be about 11 times as bulky, which means it would never fit in my BC pockets and on my belt.

Adding water to your sand does nothing at all to the "weight" once in the water.

 

[FrogManMike]

Ha ha the sand makes me neutrally buoyant with not much more bulk in comparison to lead.
for a material that you imply is impractical for what I am using it for works pretty darn good IMO.

You would have to be carrying ~19.2 pounds of sand to get the same change in buoyancy in the water as you get with 10 pounds of lead

how do you figure this? sure it will take more sand to equal the weight of lead but your surmise that it takes more weight in sand to make me as neutrally buoyant than a lesser weight of lead is totally wrong. sand is subject to the same laws of water displacement as lead is.a three pound sealed sand bag is about the same size as a 5 pound weight bag so there is not that much of a difference.

I don't understand what you meant by this...

"Adding water to your sand does nothing at all to the "weight" once in the water."

the water is vacuum sealed in the bag with the sand... weight is weight. an empty glass bottle will float, fill it with water and it will sink.

I am not making any argument, lead is a better choice of materials to use for ballast but I am frugal or you might call me a tight wad or cheap never the less sand does work.
not to mention that if it ever comes to the point I have to ditch weight I am not throwing my money at the bottom of the sea floor. besides lead is harmful to the environment, sand is not.

 

[WeldonDowd]

Frogman, if weight is weight you should just leave the sand out of your bags and just fill them with water then.

 

[skynscuba]

how do you figure this?

By subtracting the weight of the water displaced by the sand or lead.

Sand only weighs about 1.92x as much as water of the same volume. When you put it under water, you subtract off the weight of the water it displaces (1.0), leaving only 0.92x/1.92x = 48% of the above-water weight to affect your overall underwater buoyancy.

Lead weight about 11.3x as much as water of the same volume. When you put it under water, you subtract off the weight of the water it displaces (1.0), leaving 10.3x/11.3x = 91% of the above-water weight to affect you overall underwater buoyancy.

10# * 91%/48% = 19#

As far as adding water to your sand (or lead) packets: if you are sealing them water tight, it helps to have the water in the packets displace the air, thereby avoiding buoyancy owing to air in the packets. However, that is no more effective than using cloth packet material that just lets the water flow in when you submerge.

If you only need a few pounds (diving without a wetsuit, or maybe in a 3/2 shorty, or in fresh water with a shorty), the sand will work just fine.

 

[FrogManMike]

Frogman, if weight is weight you should just leave the sand out of your bags and just fill them with water then.

sand is heavier than water:mooner: