Tungsten weights for scuba

[Dominik_E]

Why not an alloy of osmium and tungsten? Then you could call yourself "Advanced Osram Diver".

You'd still have a bit of a challenge casting those weights, though.

Now you are giving me an idea. I may even take a fundamentals class, stick to German altogether, and call myself "GUEbirne"!

 

[Snoweman]

Buy gold then. Coat the weights with plastic and it's a win-win: nobody'll ever figure out where all your savings are.

And it's a great way to smuggle the gold between countries.

 

[divad]

Okay, gold it is. Thanks for the sound advice.

 

[St John the Diver]

You obviously haven't used Hevi-shot or Wingmaster HD shotshells. Those materials are tungsten-based and denser than lead. Tungsten-polymer matrix shot is about as dense as lead. It all depends on what you pack in the voids. And of course the size distribution of the particles you try to pack.

You're mistakenly assuming that the particles have to be uniformly sized spheres, and you're forgetting that the material in the voids also has a density >0

The actual point is this:

For any given volume, solid lead blocks will be denser than packed tungsten shot. The size of the shot isn’t relevant. And since I can purchase solid lead dive weights But I cannot purchase solid tungsten ones, I can categorically say that there is no advantage to using tungsten shot as a substitute for solid lead.

 

[FreeFlyFreak]

The actual point is this:

For any given volume, solid lead blocks will be denser than packed tungsten shot. The size of the shot isn’t relevant. And since I can purchase solid lead dive weights But I cannot purchase solid tungsten ones, I can categorically say that there is no advantage to using tungsten shot as a substitute for solid lead.

Tungsten shot soft weights?

 

[yle]

Tungsten shot, no matter how small, is less dense per cubic anything than solid lead. There’s a fixed ratio between the solids and the interstitial voids in any matrix of spheres of any size. It’s immutable. There would be zero advantage. In a random pack of spheres it’s about 65% as dense as a solid.

Ain’t geometry cool?

Sphere packing - Wikipedia

65% the density of tungsten is still greater than the density of lead:

Tungsten 19.3 g/cc 65% of that is 12.5 g/cc

Lead is 11.3 g/cc

So... tungsten shot (even with the voids between the spheres) is still a bit denser than solid lead. There would be close to zero advantage... but definitely a little higher than zero.

I read an interesting (to me...) book several years ago called Kepler's Conjecture. Apparently Johannes Kepler, around 1600, claimed that the maximum possible "packing ratio" for spheres is around 73%. For centuries this was taken on faith, but some mathematician was able to construct a proof of it a short while ago. It was kind of like a Fermat's Last Theorem, though... the proof was so complex that it really called into question how Kepler (and Fermat, in his case) could have possibly known it to be true at the time he made it.

 

[yle]

I can categorically say that there is no advantage to using tungsten shot as a substitute for solid lead.

Hmmm... I think one of the reasons the OP stated for tungsten over lead was "streamlining". Certainly an argument could be made that weights filled with shot are better than solid weights for streamlining, as their shape can be more easily molded to fit the profile of the weight pouch.

Of course 3 lb of lead shot takes up the same actual volume (the volume of the lead bits themselves...) as a 3 lb solid brick of lead, but the volume is more distributed with the shot. If distributed effectively, this could result in better streamlining.

But the advantage, of course, as you've pointed out, is pretty close to zero.

 

[АлександрД]

Tungsten shot, no matter how small, is less dense per cubic anything than solid lead. There’s a fixed ratio between the solids and the interstitial voids in any matrix of spheres of any size. It’s immutable. There would be zero advantage. In a random pack of spheres it’s about 65% as dense as a solid.
Ain’t geometry cool?
Sphere packing - Wikipedia

Great! And I just remember one very nice apologue. Sorry, if there is some mistakes in translation - used just Google translator, but significance is in it.

The professor of philosophy, before the lecture, enters the audience and lays on the table several different things. When the lecture begins, he silently takes a large, empty jar and fills it with large stones. Then asks:
- Is the jar full?
- Yes! - students agree.
Then the professor takes out a box of small pebbles and pours it into the same jar. He chatted lightly at the can and pebbles, of course, filled the open areas between the stones. He again asked the students:
- Is the jar full?
They laughed and agreed that the can was complete. Then, the professor takes out a box of sand and pours it into a jar. Naturally, sand fills the rest of the space.
“Now,” said the professor, “I want you to understand that this is your life.”
Stones - important things - your family, your friends, your health, your children. If all the rest was lost, and only they remained, your life would still be full.
Pebbles are other things that matter like your work, your home, your car.
Sand - everything else, it's just the little things in life. If, first, you pour sand into a jar, there will be no room for pebbles and stones. The same thing in life. If you spend all your time and energy on trifles, you will never have a place for things that are important to you. Pay attention to things that are critical to your happiness. First, take care of the stones, it really matters. Set your priorities. The rest is just sand.

But, here one student came up to the can, which, according to the others, was full, and poured a glass of beer there. Of course, beer filled the remaining space in the can. And the can became absolutely complete.

The moral of this story is: no matter how full your life is, there is always a place for beer in it!

Antiofftopic: I think tungsten has at least three great advantages: It is heavy, in same size; It is not venomous, like lead; And most important - tungsten weights should be always nice! not scratched and clapped-out.

 

[yle]

You're mistakenly assuming that the particles have to be uniformly sized spheres, and you're forgetting that the material in the voids also has a density >0

Exactly this. Using lead shot (or tungsten shot), water fills the voids. So you have a combo of volume of lead and volume of water.

And you get exactly the same volumes with a solid lead weight... but the water is just on the outside instead. Same volume of lead (for a given weight... shot or solid) and same volume of water.

 

[yle]

There would be zero advantage. In a random pack of spheres it’s about 65% as dense as a solid.

This is true when the voids are filled with air. When you're underwater... they usually fill with water. Changes the calculation a bit.

If the water weren't an issue, then soft lead weights (i.e. lead shot) would only be 65% as effective as solid lead weights. So a diver that uses 20 lb of solid lead weights would need close to 30 lb if they switched to soft weights. However, we all know from experience that this isn't how it works... soft weights, hard weights, we use the same.