I lost 10 more pounds since I last calculated my weight belt, so I had to re-do my calculation. I will post it here, and maybe we can save it in a common place, since this seems like a key question related to weight loss and scuba.
Short formula: take your body weight change (in any unit like lbs, kg, stone), divide it by 9, and that is the change you need to make to your weight belt (in the same units). Examples: I lost 27 lbs, therefore I must remove 3 lbs off my weight belt. I gained 4.5 kg, so I need to add 0.5 kg to my belt.
The Specific weight of body fat is about 900 kg/m3 (http://www.springerlink.com/content/78dlx 1566ug9eyjt/ http://hypertextbook.com/physics/matter/ density/ ). That of water is about 1000 kg/m3 (1020 kg/m3 for saltwater, but the difference is not significant enough for this rough calculation). So you take the amount of weight you lost, divide by the specific weight of fat (900 kg/m3), and that will give you the volume of mass you lost. Since that volume will no longer displace water, eureka, you can then remove the difference between the amount of weight that that water weights and the fat weights, which is 100 kg/m3, and multiply it by the volume. Since the units kg/m3 cancel each other out, the ratio 1/9 (0.111111...) can be used with any units.
current weight: 88.0
Fitness Minutes: (140) Posts: 755 7/7/08 7:07 P
Maybe we should offer a weight-loss weight-belt adjustment table, formula, or calculator. It's relevant to both weight loss and scuba!
Wow! Congrats PelagicSal!
Rutell, yes: you do waste a lot of tank air to buoyancy adjustment (both via BC, and breathing) the more wetsuit you have, because it causes more buoyancy differences as it compresses. I sometimes have 12 mm of neoprene in my core.
I would be interested to know the exact specs, but I bet you do lose some air on buoyancy adjustments. It certainly takes a lot more tweaking than in warm water. I kind of make it my mission to use as little air as possible, but in cold water that is indeed more difficult. It helps to be smaller, though. My husband always uses way more air than me. The other key to air conservancy is to go as slowly as possible and to maintain yoga-like breathing. The calmer you are the less air you use - but of course, you are probably not expending as much energy and burning as many calories.
And after 20 minutes in 50 degree water I can't feel my fingers. You have to be pretty hard-core to dive in CA. Anyone tried diving in Lake MI?
A couple of weeks ago I had lost about 20 lbs (9 kg) of fat since my last buoyancy check, so I ran the numbers on dry land and decided that I could remove 6 lbs (almost 3kg) from my weight belt! (I found/assumed that specific gravity of fat is about 800 kg/m3.) I went on a boat dive with 4 less pounds (almost 2 kg), and was still too heavy at the safety stop at end of the dive! So my 6 lbs calculation was probably right.
I have lost 6 more lbs of fat since that buoyancy check! My weight belt is starting to look more like a warm water diver's. ;)
Anybody else has been rewarded like this by the forces of diving? Wow!
Alef - You gotta get me drysuit certified before I attempt to dive 80 minutes on a single regular tank in the Northern California coast. I made 60 min in Victoria, BC, but I was wishing for a drysuit! And you just might want to dive with me. I've got excellent references. Air consumption has been very good ever since I was certified, and though I know I did it once, I have NO idea what my consumption rate is.
Snork - You won't belieeeeeve how much better scuba is!!! If you are surface diving as you snorkel, you'll also be surprised how much easier diving is physically.
Edited by: PELAGICSAL at: 5/3/2008 (15:33)
So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover. - Mark Twain
Man cannot discover new oceans unless he has the courage to lose sight of the shore. -Andre Gide
Not one shred of evidence supports the notion that life is serious.
I can't tell you guys how much I want to learn to dive! Snorkeling is my passion, but if I love snorkeling this much, can you imagine how much I will love diving. I love reading all your stories. Someday I will be adding my own! Barbie
If you can dive 80 minutes on a single regular tank in the Northern California coast, I want to dive with you. :) In my Florida coast dives off of Miami with 78 F water, my Respiratory Minute Volume was 65% of what it was here at the time in California in 50 F water.
Actually... just writing this made me realize that if the air consumption is higher in colder water, the calories burned must be higher too. Unless the extra air is lost to buoyancy adjustments due to the extra neoprene/air and weights. So little I know... :)
This is a very intersting question Alef. I know the body uses more energy to keep warm but to what extend? If anybody knows this please enlighten us. I may just learn to start loving cold water diving.
I think it would depend on the intensity of the 40 min dive versus the 40 min walk. According to Sparkpeople cardio tracker 40 min Scuba divin = 280 calories and 40 min walk 30min/mile = 112 calories. If you walked faster you would burn more calories.
Edited by: MICHELAR at: 5/1/2008 (10:26)
“Energy and persistence conquer all things.”
We cannot discover new oceans unless we have the courage to lose sight of the shore. (Anonymous)
From wine what sudden friendship springs! (John Gay 1685- 1732)
Fitness Minutes: (140) Posts: 755 5/1/08 4:35 A
Hi, does anybody have information on the effect that cold has on weight loss? I found some good articles analyzing weight loss with steady aerobics vs. HIIT etc, and I am looking for an equally informed analysis of calories consumed by thermogenesis.
Some of us dive in really cold water and must hence use a lot of energy to produce heat; but even in moderate water in a wetsuit, we must generate heat to warm the water. How much calories does that consume? Does it have long term EPOC or something?
How does a 40 minute dive compare to a 40 min walk? Does it depend on the water temp?
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