Approximate Additional Weight for Salt Water?

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SlugMug

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Standard Disclaimer: Everyone should do the standard weight-checks, and adjust their weight according to their buoyancy at the beginning and end of a dive.

It occurs to me I have no idea how much additional lead I'll need for diving in salt-water. I'll know the answer to my question in a few days, but wanted to create this thread to be potentially useful for others. I'm curious if people could share the difference in weight they tends to use when diving in salt versus freshwater. If you can share:

Generally:
  • Body-Weight lbs/kg
  • BCD / Rig type & Tanks - Ideally shared between setups below.
Setup/Environment:
  • Amount of Lead
  • Wetsuit thickness, or drysuit
  • Salt or Freshwater

For example:
  • Weight 165lbs / 75kg
  • sidemount, no backplate but plenty of hardware, Alternate between 2x AL80, or 1x80 & 1x full AL19
Setup 1:
  • 5lbs / 2.25kg lead
  • 5mm wetsuit
  • freshwater
Setup 2:
  • ??? lbs lead - Hopefully I'll know soon, this is just an example
  • 7mm wetsuit
  • salt-water
 

Jcp2

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Weigh the total dry weight of you and all your gear and tanks that gives you your desired buoyancy in fresh water. Assuming that sea water is 2.5% denser than fresh water, then you’ll need an additional 2.5% of that weight in lead to match the same buoyancy. For me it’s about an additional 5 pounds, all other things being the same. I’m guessing that you will need an additional 4 pounds for the thicker suit and another 5 pounds for salt as well for a total of 14 pounds.
 

inquisit

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You can nail down the difference due to the wetsuit if you can measure their fresh water buoyancy and take the difference. (Not sure if you have access to Suit #2.)

Then scale the new total to salt as @Jcp2 described.
 

fsardone

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I have always envied fresh water divers. Especially when I am cleaning my gear after a weekend of salt water diving lol
Do as I do …. fresh water dive after sea dive! :wink:
 
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SlugMug

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I have results! This isn't super-precise for a few reasons, I'll mention below, but onto the results.

Both:
  • Weight 165lbs / 75kg
  • sidemount, no backplate but plenty of hardware, 1x AL80 + pony bottle.
Setup 1:
  • 5lbs / 2.25kg lead
  • 5mm wetsuit
  • freshwater
Setup 2:
  • 20 lbs / 9kg lead
  • 5mm wetsuit, or 7mm wetsuit (I tried each & weight didn't seem to change much)
  • salt-water
Why is this not precise? I was really cold most of the time, and probably more buoyant due to reduced control of breathing and muscles. I also didn't have much time for checking or adjusting weighting. However, I did feel almost-but-not-quite underweighted.

I actually did one dive (at 15ft) while very underweighted (~12lbs) because that's all I had at the time, max 15ft depth, and I was miserable. I didn't do anything dangerous, but that dive was rather miserable, and there wasn't much to see anyway. After I wore myself out on an absurd attempt, I basically snorkeled with the scuba-tank back to shore.


I have always envied fresh water divers. Especially when I am cleaning my gear after a weekend of salt water diving lol

The sea-life was FAR more interesting to say the least. However, holy **** salt water is a much bigger pain than I expected. I was surprised by how much salt appeared on a couple items I didn't adequately rinse, a couple cheap clips needed to be re-washed to close, and a couple cheap "stainless steel" items rusted. Plus everything was somewhat sticky if inadequately washed off.

I'm sure I could develop a system of dunking my equipment in large tubs of water after every dive, if I lived in the area. However, if I'm traveling & doing normal-dives, I'm thinking a better option is to bring my compact/cheap/spare scuba-equipment I never use, leave my nicer stuff at home, and rent weights.
 

Diesel_Diver

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Cold HAHA and people wonder why I need 50+ lbs of lead and an HP 133 but I am rarely cold (even in the winter) . As far as rinsing goes, I carry my gear to and from the dive site in a plastic tote, so I just fill it with fresh water and soak it a few hours.
 
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SlugMug

SlugMug

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Cold HAHA and people wonder why I need 50+ lbs of lead and an HP 133 but I am rarely cold (even in the winter) . As far as rinsing goes, I carry my gear to and from the dive site in a plastic tote, so I just fill it with fresh water and soak it a few hours.
:rofl3:

There's a slight possibility I may move in the next few months to a cold-location, within a short drive from the ocean. I imagine if I do, a dry-suit and lots-of-lead is in my future.
 
https://www.shearwater.com/products/peregrine/

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