Added lead for 2.5mm hooded vest

[Divectionist]

Hi

My current gear is perfectly weighted with 4lbs of added lead (total weight with 4lbs of lead + backplate, STA, fins, lights etc. is 12lbs) for 5mm.

I picked up a 2.5mm hooded vest (SP everflex neoprene in size L) which I will wear over the wetsuit.

How much lead would you add to compensate, if any? I've got 1lbs increment weights. One of those things I want to get approximately right in theory before confirming in practice. Also diving got cancelled this weekend so no question is too small!

Edit: It sinks between 2 and 3 lbs in my freshwater pool so let's call it 2.5lbs in fresh, approx. 3lbs in salt? Perhaps just 2lbs at 5m depth?

Thank you

 

[MichaelMc]

If it is neutral in your pool, it (hood + lead) must weight as much as the water it displaces.

How much more does that much sea water weigh?

 

[Divectionist]

If it is neutral in your pool, it (hood + lead) must weight as much as the water it displaces.

How much more does that much sea water weigh?

I usually multiply lead in fresh by 0.25 for lead in salt, see my calculation above.

It is neutral between 2 and 3 lbs (say 2.5), so around 3 in salt. Then my assumption is to drop 1 lbs for compression at 5m. Is this wishful thinking to keep the number I need to add even, so that I don't have 1lbs more on one side?

 

[rsingler]

2.8lb surface SW, 2.7lb fresh water (~3% fresh vs. salt)
~2.1lb @15' (an extra half atmosphere, but the neoprene cells offer some resistance to compression).

Add 1 lb each side, control the rest with breathing.
0.8 lb = 1.5 cup of air maximum
At 15'? You're perfect.
Near the surface? Exhale about a cup.

 

[Divectionist]

Thank you, will go with 2 extra in the upper cam band trim pockets, given that this is top-heavy neoprene, and see how it goes

 

[decompression]

Put it in a mesh bag......place weights in the bag until it sinks in water......that’s how much you’ll need.

 

[Divectionist]

Put it in a mesh bag......place weights in the bag until it sinks in water......that’s how much you’ll need.

Yeah I've done that in fresh water as per my initial post. I wanted to confirm that my assumptions for fresh to salt and then to safety stop depth made sense also. It takes a bit over 2lbs to sink but I'll cut it down to 2 to account for 1.5 ATA.

I am a bit annoyed by the gear change because I just tweaked my relatively new gear setup for trim and neutral at the safety stop, and I don't want the hooded vest to throw out either or require an unbalanced weight distribution if I need to add an uneven amount of lead across my 4 fixed weight pockets.

 

[Graeme Fraser]

Yeah I've done that in fresh water as per my initial post. I wanted to confirm that my assumptions for fresh to salt and then to safety stop depth made sense also. It takes a bit over 2lbs to sink but I'll cut it down to 2 to account for 1.5 ATA.

I am a bit annoyed by the gear change because I just tweaked my relatively new gear setup for trim and neutral at the safety stop, and I don't want the hooded vest to throw out either or require an unbalanced weight distribution if I need to add an uneven amount of lead across my 4 fixed weight pockets.

For an individual item with only 2lb positive buoyancy the difference from fresh to salt will be negligible at 3%. Is the hood vented as air sometimes gets trapped?

 

[Divectionist]

Is the hood vented as air sometimes gets trapped?

Oddly enough it is not, however, I took a heated O ring pick to it and it now has 3 vent holes

They are only 1-2mm wide, I may widen them or add more if I get the cone head. Yet to dive with it thanks to the large swell here.

 

[Akimbo]

2.8lb surface SW, 2.7lb fresh water (~3% fresh vs. salt)

Agreed. For reference:
Fresh water weighs:

• 1 Liter = 1 Kg = 2.2 Lbs
• 1 Ft³ = 62.29696 Lbs

Seawater varies but the average is generally agreed to weigh:

• 1 Liter = 1.0289 Kg
• 1 Ft³ = 64.1 Lbs