DShaw
New
Transitioning from warm salt water to cold fresh water with new gear. male, experienced diver, 245lbs, fresh water, 7mm suit, 7mm hood, 5mm gloves, AL 80, 5lb back plate...any recommendations on weighting?
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I'm 220 lb, 6'2" and use 12 lbs in those conditions. Hope it helps!
Bring a float tube with extra weights in it and anchor it in about 25 ft. Then breath down your system to 500psi and add or subtract weight as needed. In my opinion, the perfect amount of weight is the minimum needed to comfortably hover at 15ft with 500psi....... then add two lbs.
Alaskan Scuba Dude
Banned
For the amount of dives you have logged, I would have thought you would have some idea...
If you have both wetsuits, you could measure the buoyancy of each and add lead in the amount of the difference. Similar for other components if they are different, but the wetsuit and backplate will be the lions share of the difference. FWIW, my 7mm wetsuit has 8 lbs more buoyancy than my 3mm.
Just noticed you're also going from salt to fresh water. First, figure the total lead you would need for saltwater (as above), then scale to fresh water by dropping 2.4% of your total mass (you + gear). Ballparking that at 290 lb, drop 7 lbs (=290*0.024) for freshwater.
If wetsuit/gloves/hood & freshwater are the only changes, I would add 2 lbs to your warm/saltwater lead count and give it a go.
If wetsuit/gloves/hood & freshwater are the only changes, I would add 2 lbs to your warm/saltwater lead count and give it a go.
OP
DShaw
New
I appreciate the input on this thread. I recently gained 45lbs. As an instructor, I kinda know that I'm now outside the window of normal weighting formulas. I also tired calculators but they are all over the place. It would be nice to actually have the buoyancy specs for each piece of neoprene gear.
Inquisit,
Not to hijack the thread, but your post raises a question.
I was told long ago that because salt water is 3% more dense than fresh water, one should use 3% as the conversion factor.
Experience--both my own and that of others I've dove with--always indicated that 3% was too big of a correction factor. Based on that experience, 2.4% seems like it would yield more realistic numbers. I'd like to believe it. I'd like even more to understand it.
What is that number based on?
Thanks,
johndiver999
Contributor
density of seawater is close to 1.025 (actually specific gravity)
density of freshwater is close to 1.0.
the difference is 2.5 %
from the internet
What is the density of freshwater and saltwater?
Conversely, as a fluid's salinity increases, so does its density. Therefore, colder salt water will sink below warmer, freshwater. Because saltwater is denser (1025 kg/m3) than fresh (1000 kg/m3), objects, including humans, are better able to float in saltwater.
density of freshwater is close to 1.0.
the difference is 2.5 %
from the internet
What is the density of freshwater and saltwater?
Conversely, as a fluid's salinity increases, so does its density. Therefore, colder salt water will sink below warmer, freshwater. Because saltwater is denser (1025 kg/m3) than fresh (1000 kg/m3), objects, including humans, are better able to float in saltwater.
johndiver999
Contributor
I would suggest 15-18 lbs and probably be able to drop 5 or 6. but it depends on wetsuit too, two piece one piece, age of suit etc.
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