lift????????????????????
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The buoyancy is equal to the weight of the water that you are displacing minus the weight of the object that is displacing the water. So what is the weight of the tanks and drysuit, what is the volume that each is displacing?
e.g. - If you are displacing 1 cubic foot of water with an object that weighs 30 lbs. than the resultant buoyant force would be ~32.4 lbs. This is assuming that 1 cubic foot of water weighs 62.4 lbs.
omar
e.g. - If you are displacing 1 cubic foot of water with an object that weighs 30 lbs. than the resultant buoyant force would be ~32.4 lbs. This is assuming that 1 cubic foot of water weighs 62.4 lbs.
omar
chris_b
Contributor
Hey, I'm almost done with my Ph.D. Does that count? Or am I disqualified just because I'm ABD?
scubaturek
Guest
I love questions like this. I don't use "calculations" because they can be inaccurate. You can physically determine how much weight you'll be wearing. How much weight (lead) do you need to just get negative with only your suit on? In shallow water, inflate your rig and float it on the surface. Use your longest hose as a hookah, and play with a weightbelt (you can lay extra weights on your floating rig). You're wearing your mask, fins, and hood, right?
Next, how much does your complete rig weigh in water? With full tanks, get all the air out of the wing (we're in shallow water again) and sink it. Then, use a spring (fishing) scale and weigh it. Do this with accessories (lights, reels, spools, knife, etc.) attached, and again without. You may also want to try this with empty tanks.
Remember, you need to be neutral at 10 feet with almost empty tanks, so, at the beginning of the dive, you're overweighted. If you jump in with full tanks, maybe a deco bottle or two, and all kinds of toys, and you didn't zip your suit, and it totally floods, this is worst case. You need enough lift to get the complete rig plus all the accessories and any lead up. The flooded suit doesn't weigh hardly anything, it's mostly neutral, but you can't use it for lift (actually, you still can, but let's pretend). You know exactly how much lift you need because you weighed everything. Keep in mind, you want some extra lift to float your head well out of the water.
Joe
Next, how much does your complete rig weigh in water? With full tanks, get all the air out of the wing (we're in shallow water again) and sink it. Then, use a spring (fishing) scale and weigh it. Do this with accessories (lights, reels, spools, knife, etc.) attached, and again without. You may also want to try this with empty tanks.
Remember, you need to be neutral at 10 feet with almost empty tanks, so, at the beginning of the dive, you're overweighted. If you jump in with full tanks, maybe a deco bottle or two, and all kinds of toys, and you didn't zip your suit, and it totally floods, this is worst case. You need enough lift to get the complete rig plus all the accessories and any lead up. The flooded suit doesn't weigh hardly anything, it's mostly neutral, but you can't use it for lift (actually, you still can, but let's pretend). You know exactly how much lift you need because you weighed everything. Keep in mind, you want some extra lift to float your head well out of the water.
Joe
Whey'll....
I replaced:
"First we need an educated question."
with:
Because I'm trying to be nice today...
I replaced:
"First we need an educated question."
with:
Because I'm trying to be nice today...
Assuming you're correctly weighted so you're neutral with empty cylinders, a wokring dry suit not being used for buoyancy and dual 108s, you'll need about 17 pounds of lift to be absolutely neutral at the start of the dive.
Roak
Roak
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