Figuring new lead requirements when you’ve lost bioprene?

[inquis]

The test ultimately comes at the safety stop at the end of the dive for the diver to determine how much to inflate their dry suit for comfort.

Oh sure, the suit needs to be inflated to the desired level of comfort for the stop(s).

My point was that you only need a single test with a trial weight within a very broad range. I recently dove my layers doubled up and was very uncertain how much lead to use. (I had never dove in 4*C water before.) Trying to guess & test the lead that I actually needed was likely to put me over (technically 50%, but the odds tend to slant toward making more work somehow), which would have forced me to translate "how squishy is my wing" or "how much air comes out I dump the rest" to lbs of lead to drop before another trial. Or the typical, knock off 1 or 2 lbs and test again (perhaps followed by another reduction/test after that). Instead, I went 4 lbs short of what I thought I would need and a single dive gave me the answer. Since I was sidemounting AL80s, my initial guess only had to be within +- 6 lbs, which is a pretty forgiving range.

It's just an alternative to the typical approach of hang out in the pool or next to a boat and add lead until there's too much, then take "some" off (but not too much, or course). Good luck if you only have access to large bricks. (My smallest were 5 lbs.)

 

[Seaweed Doc]

Losing bioprene may not make much difference. There are a couple of key issues here:

1. Have you decreased volume much? Seems like the math calculations assume you have. I suspect you have, but will it be in the right place to actually cause a reduction in the volume of your dry-suited self underwater? Will the volume loss be more than enough to overcome the weight loss?

2. Has some of the loss been muscle? For most folks losing weight, you lose primarily fat but you also lose a bit of muscle.

If it were me, I'd try it with my formerly perfect weighting, then do a proper post-dive weight check with near-empty cylinders. Play around with it and see. Have some one pounder weights you can ditch in shallow water when you do the weight test. (Or whatever makes sense for a worst-case CCR scenario where most of your gas is gone and you need to hold a shallow stop a bit longer.)

 

[Matan]

st 12 lbs over the winter and continue to lose. I now have to figure out my weighting again. Last time I dove my CCR with heavy undies was late October. I needed 26 lbs with one AL40 for dilout (Kiss Spirit). I’m switching to a pair of LP50s, which seems to take me down to 22lbs.

Now that I’m down 12 lbs of bioprene, how much less should I be able to shed?

Just repeat the check you did when first trying to balance your rig the first time.
No magic math here - Need to test in the water.

Thanks,
Matan.

 

[rddvet]

Not to come off gruff, but no one is going to have a magic scientific answer. Pull a small amount of weight off. If you’re a little heavy deal with it a few dives to figure out your trim. Then take off more and repeat. If you take some off and you’re too light, you know what to do. No fancy maths or science. Just trial and error.

 

[scubadada]

For anyone, just do a good weight check at your safety or last deco stop with no air in your BC. It is easy to adjust your weight. I changed 3mm full suit and had to add 2 lbs.

 

[undrwater]

Good problems to have.

 

[inquis]

It's still good to have an ESTIMATE for how much to change. I think that's all Marie was looking for. I'm pretty sure she intended to evaluate at the end of the next dive.

 

[Marie13]

Took 4 lbs off today. I’ll dive another day with it, but I felt a tad bit heavy today. Or I could try adding my buoyant Fourth Element X-Core vest that requires 2 lbs and see how it is.

 

[RedSeaDiver2]

Took 4 lbs off today. I’ll dive another day with it, but I felt a tad bit heavy today. Or I could try adding my buoyant Fourth Element X-Core vest that requires 2 lbs and see how it is.

I'm still at the trying to lose the bioprene stage...