Weight check, Full breath, Normal breath, or no breath?

When doing a weight check, do you hold a full breath, normal breath, or exhale completely?
I have a feeling theres different opinions on this one

Exhale completely.

If you're talking about a weight check on the surface at the beginning of your dive, then you empty your BC and with a medium breath, you should be at eye level. When you deeply exhale, you should begin to sink.


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The choice is up to you. There is no "weighting" police. You do want to protect against being too light at the end of the dive. Just keep in mind the condition for which you are weighting yourself: end of the dive, no gas in BC, empty/near empty tank, being able to comfortably hold your position in the water column at safety stop depth or shallower. I do a lot of shore dives which end in very shallow water (approx. 3 fsw), so I weight myself accordingly.

The average male can compensate for a buoyancy swing of approx. 10 lbs. with his lungs alone (full vs. empty), so this tidbit of info might give you an indication of how much of a difference your breath status influences the weighting requirement.

Another variable, if you are conducting the weight check at the beginning of the dive and you are wearing a wetsuit, is that your wetsuit will not have as much inherent positive buoyancy at the end of the dive. It gets crushed at depth and won't spring back 100% by the end of the dive. If you're curious about the magnitude of this effect, simply test it out on your next dive.

If your goal is to get your weighting "perfect," then it's important to know the magnitude of the effects I just pointed out. In practice, it's probably best to err on the side of being slightly heavy. As you know, it can be dangerous to be grossly over-weighted or under-weighted.

FYI, don't forget to compensate for any remaining gas in the tank while you're conducting the weight check.

If your eyes are level with the water with a full tank, you are probably going to be light at the end of your dive. Here's how I get my students figured out.

BC empty, hands and feet crossed (stops kicking and sculling) with your regulator in your mouth. Look at the average height the head sticks out of the water. For every inch add a pound. For every 25 mm add 0.5 kg. Let the person hold this while breathing normally and recheck. You're done when the top of the head is just awash (starting to drift down) and you probably won't be light during your safety stop.

I like that Pete. Gonna have to try it with some people. But for the OP I usually exhale deeply, not necessarily completely because will you really empty your lungs all the way during the dive?

fisheater:

If you're talking about a weight check on the surface at the beginning of your dive, then you empty your BC and with a medium breath, you should be at eye level. When you deeply exhale, you should begin to sink.


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+1 Exactly right.

blackvans1234:

I have a feeling theres different opinions on this one

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Not necessarily...normal breath eye level is the text book answer. Some folks will then exhale to start going down while other will recommend inhaling first and then....exhaling. If done with a tank that has 500 psi left then you should not be light at 15 ft. If done with a full tank, go through the internet to find the specs of your tank and add enough weight to compensate for its buoyancy as air is being consummed.

I think OW instructors really short-change their students if they state that there is only "one way" for a diver to weight himself properly...without explaining the reasoning behind doing the check in a particular way, discussing various factors which affect weighting, and allowing the student to experiment with different weighting techniques.

If you are doing the weight check at the beginning of the dive, with a full tank, then at the end of the dive, with an empty tank, you will be at least roughly five pounds lighter. IF you want to be able to control your ascent all the way to the surface, you don't want to be five pounds light there. (Although you most likely will have lost a little lift, due to gear getting saturated with water, wetsuit compression that hasn't totally rebounded, etc. -- and in a dry suit, it may work the other way, because you were totally squeezed, hanging vertically in the water at the beginning, but you almost certainly can't get the suit that empty at the end of the dive.)

So, if you are neutral with a full breath at the beginning of the dive, you're probably several pounds negative with a normal one, which is where you want to start your dive. It's a rough way of determining correct weighting.