weighting between fresh and salt water

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If you are properly weighted in freshwater and you know the total weight of you and your equipment, add 3% of that total weight going to saltwater. The simple fact is that saltwater is 3% denser than freshwater, and so the buoyant force acting on you in saltwater is 3% greater than in fresh (and if you're neutral, that force in fresh is equal to your weight.)

For most people, this means if you and your equipment weigh 130 pounds you should add 4 pounds. If you weight 270 pounds, you should add 8 pounds. If you're in between, add something in between.

Of course this assumes you are properly weighted in FW to begin with and you'll be using the same equipment in both environments.
 
i did my open water back in Sept up here in Saskatchewan and was wearing a 7mm john and 7mm jacket with 28lbs of weight fresh water .i was heavy but i think they do this to help you stay grounded for the skills but was having a hard time controlling buoyancy..by the way im 5.6 and 190 lbs not fat but wide .at the pool im wearing just 2mm shorty that i plan on wearing in the Caribbean in January .ive been going to a few splash sessions working on my buoyancy skills and in just 2 splashes since ow certification i went from 16 lbs of lead down to 10 with waaaaay better control im going to try 8 this weekend coming up,my question is going to salt water being more buoyant what should i need for weight .now that learning control i dont want to loose that being overweight on my dives im thinking double of what i wear in fresh so about 16 lbs does this sound correct.ps i have my own gear so wearing different wont be a issue

Sadly, you may be right on why they overweighted you if they did. Easier to control people if they are planted on the bottom. Makes the dive riskier though as it makes it harder to control your buoyancy. Some also do it because they don't know how to properly weight a student. Diving a pound or two heavy is no big deal. The first time you hit saltwater do a proper weight check. 4-6 lbs vs fresh is about right to start.
 
@Painter I think that Dive Buddy calculator is off for most of us by at least 5 lbs.
 
I am a novice. On my last dives in salt water I found 12 pounds to be just about perfect. The calculator tells me that I should be carrying 17. Granted, everybody is different, but that seems pretty far off to me.
Free calculators are actually worth about what you pay for them. There is no substitute for a proper check.
 
We both are right.
There are different body structures and forms. I'm lucky that the standard wetsuit for my weigh fits me as paint.
I've meet many people in the dive school with different body mass and what's too much for some is too little for other, perhaps with the same weight. Muscle mass, fat, fitness, air capacity, the way you breathe, gear, experience and a lot of other things contribute to the amount of weight needed to be neutral underwater.
Of course that a weighting calculator will be accurate in some cases and completely unaccurate in others. Everyone is different. However, some tendencies can be seen in the way people dive. Those tendencies can be drawn in an algorithm that could predict the amount of lead some one could need as a starting point.

Another point to consider, that perhaps is not taken into account in that so criticized calculator is that new neoprene wetsuits are far more buoyant that old and used neoprene suits, however both old and new are of the same thickness.
A brand new wetsuit can be 2 to 4 times more buoyant than the same suit with hundreds of dives.
Rented wetsuits are in the second group.
At least my current wetsuit, though I have been using it several times, is practically new, and so, much more buoyant that those rented elsewhere.
Also, that calculation is valid for me because I always use boots, gloves and hood, adding a lot of buoyancy that has to be compensated with lead. This last point is also not considered in that calculator. I agree that there is no mention to those miscellaneous items.
 
If you are properly weighted in freshwater and you know the total weight of you and your equipment, add 3% of that total weight going to saltwater. The simple fact is that saltwater is 3% denser than freshwater, and so the buoyant force acting on you in saltwater is 3% greater than in fresh (and if you're neutral, that force in fresh is equal to your weight.)

For most people, this means if you and your equipment weigh 130 pounds you should add 4 pounds. If you weight 270 pounds, you should add 8 pounds. If you're in between, add something in between.

Of course this assumes you are properly weighted in FW to begin with and you'll be using the same equipment in both environments.

Density of Seawater

A more precise estimate would be 2.5% but we are splitting hairs now.

If you know what you need in freshwater, it should be easy to figure what you need for saltwater. A "calculator" is a rough estimate and is worthless compared to your data generated in freshwater.
 
Another point to consider, that perhaps is not taken into account in that so criticized calculator is that new neoprene wetsuits are far more buoyant that old and used neoprene suits, however both old and new are of the same thickness.

Don't forget the inherent buoyancy of a BC, mine was about 5# buoyant when empty, others will vary.


Bob
 
I am a novice. On my last dives in salt water I found 12 pounds to be just about perfect. The calculator tells me that I should be carrying 17. Granted, everybody is different, but that seems pretty far off to me.
I easily believe that. With an AL80 in the tropics in a body suit only I needed 10 pounds.
 
This debate could go on for years. As has already been stated everyone is different body mass wise.
It was well worth the tank rental for me to find my proper weight and to understand the effects on my buoyancy as the tank emptied.
When you finally control your position in the water by inhalation or exhalation depth it is very satisfying.
 
https://www.shearwater.com/products/swift/

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