Precision of weights - Tolerance

[miketsp]

I've just been looking through the thread about how much weight do you carry etc and I saw quite a few inconsistent answers. So either many of the so-called 7mm wetsuits have thinned down with use or people think they are diving with a weight which is not correct.
After an experience in Cuba with weights that had variable proportions of Tin & Lead - in a week's diving I didn't do 2 dives with the same weight, when I got home I weighed all the weights we have (3 divers in family).
I found that our 2kg weights varied from 1.6kg to 2,2kg and none of our 3kg weights weighed more than 2.6kg.

That's quite a tolerance and a bit of a rip-off considering we pay by the kg.

I remember reading similar complaints from muscle builders and Physiotherapists where it is important to have precision weights for exercises.

So I'm curious, anyone out there weighed their weights and how does this vary from country to country.

 

[Don Burke]

So I'm curious, anyone out there weighed their weights and how does this vary from country to country.

I dive at the Virginia Aquarium and there is a bucket of weights, many with the original markings worn off. One morning a couple of us found a scale and started weighing them. I weighed them all and while I do not recall much in the way of specifics, I do recall that the results were similar to what you found. It was not unusual to find a five pound weight that was more like four and a half.

The money I could get over. The lack of consistency bugs me.

 

[The Kraken]

Geeeeezzzzzzzzz, Mike !!!!

Now there's something else I feel compelled to do when I get home this afternoon! :05:

the K

 

[cummings66]

Many dive shops cast their own weights from wheel weights so there is bound to be variances in them.

For me I cast my own weights and have weighed them myself after I finished to be sure I had what I thought I did.

I thought I used 16lbs on my 7mm in fresh water based on what I had, 1 lb ingots for testing that I borrowed from my reloading supplies. I recently decided 16lbs is exactly right for me and cast them into custom shapes for my BC and tank and then weighed what I had, 16.1 lbs was the result. My lead comes from wheel weights I melt down for reloading purposes, and it's not quite pure lead. If I remember correctly I believe I have about an 8 on the brinnel hardness scale so it's not far from lead.

 

[Whatgoesdown]

Just to throw another spanner in the works, water varies in its salinity (or lack thereof) around the world so displacement will also vary. Usually, it is not a huge amount but coupled with the difference in weights you are best off finding what works and sticking with it for the day/month/year.

 

[Walter]

This is common in hard and soft weights. They are rarely as advertised. Amazingly enough, it's even true with fishing sinkers that are measured in ounces. (I dive with fishing sinkers)

 

[Don Burke]

Just to throw another spanner in the works, water varies in its salinity (or lack thereof) around the world so displacement will also vary. Usually, it is not a huge amount but coupled with the difference in weights you are best off finding what works and sticking with it for the day/month/year.

The problem is that unless you are using the same particular weights, what worked yesterday will only give you a rough guide to what is going to work today.

I can get over a salinity change as that can be measured and accounted for.

Having to account for a 10% variation in factory produced weights would seem to be silly.

 

[hvulin]

Just take a little bit more weight with you and fix the problem on site... I don't really care about the number describing the amount of weight I use - I know approximately how much I need and than just add/remove a little on the dive site

 

[Blackwood]

Same is true with most any weights. Go into a gym and pick up a dumbell labeled 50 pounds. It probably weighs more like 49.

 

[miketsp]

Just to throw another spanner in the works, water varies in its salinity (or lack thereof) around the world so displacement will also vary. Usually, it is not a huge amount but coupled with the difference in weights you are best off finding what works and sticking with it for the day/month/year.

Yeah but the problem we had in Cuba (Isla da Juventud) at the beginning of this year was that there was a shortage of lead so during your SI, someone else would be diving with your weights. So weight belts were being constantly mounted and dismounted.
1st dive I couldn't get down, 2nd dive I went down like a brick with the same number of blocks. Then it sank in that the duller the block, more lead - heavier, shinier block, more tin - lighter. By the end of the week I could look at a block and judge its weight by its colour.