RDRINK25
Contributor
I have tested my rig in fresh water and it feels like a lb or two negative. When I get it in salt will it be positive? It is a T2i in a Sea&Sea RDX 550 with 2 ys-01's.
buoyancy ?
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fisheater
Contributor
Weigh yourself. Weigh all your gear, including your weight and tanks. Add them.
Multiply by 2.5%.
That's how much more lead you need for saltwater.
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Multiply by 2.5%.
That's how much more lead you need for saltwater.
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elan
Contributor
OP
RDRINK25
Contributor
charlesml3
Contributor
Nope, sure won't. You probably won't even notice the difference.
Your rig should be neutral or so close it doesnt matter. Hopefully your rig is at safety stop psi. It is all a wash to some point. the comversion for salt water is applied to you and all your gear. If you are happy with your bouyancy is fresh water, then do what others have suggested and get it all on a scale and use that weight and add 2.5%. example. i am 250 and my gear at 400 psi with 3/2 shorty is about 320# i use 8# of extra weight for walt water. Where you will have problems is when you change wet suits also as you go from fresh to salt. salt water is 2.5% more dence than fresh water. IF you go somewhere where the salinity is 40-50 ppt than you will have to use perhaps 3% of weight. obese or beanpole makes no difference cause you are right with the world when you were in fresh water.
CT Sean
Contributor
For the record, he's talking about his camera rig, not his whole self.
Well its very easy, when you enter the water with all your rig set on remove the air from the BCD and full your lungs with air if you stay only with your head out of the water you are ok. It means that when you finish the dive with your lungs full you´ll stay with water by your chest.
fisheater
Contributor
not exactly. Doing this, you would be fighting to hold a safety stop at the end of the dive.
I believe you are referring to the PADI (and probably others as well) way of determining the weight to carry. In this method, you should be floating at eye level, rather than having your whole head out of the water. You should also not fill your lungs, but rather just take a normal breath and hold it. Lastly, you need to add weight to compensate for the gas you will use during the dive. All of this is designed to approximate being neutrally buoyant at the end of the dive with no gas in your BC. So, a better way to check for buoyancy is to do just that, with a near empty tank (500psi or less) and no gas in your BC, find the least amount of weight needed to comfortably hold a safety stop.
However, I believe the OP has their buoyancy figured out in fresh water, but is just looking for a way to transfer to salt water without doing a buoyancy check. Presumably because it is time consuming swapping weights out at the back of the boat trying to find the right balance, and not a good way to make friends with the other divers. Personally, I would make a good guess based on the suggestions in this thread, add a couple of pounds to be sure, and then see what happens at the end of the dive while doing a safety stop. If you dump the gas out of the BC and sink, I would go 2lbs lighter on the next dive and once the right combination is found, I would write down all of the equipment I was wearing, and how much weight I needed in my log book for future reference.
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