Weight question

[chidis]

Hi,
I'm fairly new and checked my OW book but couldn't find the answers to these questions
1 - In what situation would I need to ditch my weights (I'm thinking maybe if my buddy is unconscious?)

2 - How do I figure out how much weight I need?

Thanks in advance-
Donna

 

[Humuhumunukunukuapua'a]

Generally, you only ditch your weights to establish buoyancy at the surface, such as in the case of you or another diver panicking at the surface. It can be dangerous to ditch weight when submerged because it can cause a runaway ascent. But the bottom line is that it's always better to ditch weight if you can't get to the surface.

If you haven't taken the class yet, have your instructor help you figure out the right amount of weight for you. Since everyone is different, it's something you really need to do in the water. It depends on how much exposure protection you wear and how naturally buoyant you are. The short answer is that when properly weighted, with your BC fully deflated at the surface, you will float at about eye level with a "normal" breath, and you will descend when you exhale that breath.

There are lots of discussions of proper weighting if you poke around this forum. Cheers!

Gregg

 

[BabyDuck]

you'll get lots & lots of answers. these are my personal views, and you'll have to think them all through for yourself, too, and decide on your personal views.

1) you ditch weights at the surface if you're in trouble and can't stay buoyant, like maybe suddenly there's bad waves and spray and you need to be higher out of the water to not get smacked and so the boat can see you better. you need to ditch weights underwater if you're at the 'better bent than dead' crossroads and plan on hustling up, calling dan, and going for a chamber ride. my personal views lead me to not worry about ditchable weight. i usually use ankle weights in my crotch strap - technically ditchable but out of my way.

2) practice. keep track of what you're wearing (more neoprene takes more weight to sink it), what tank you're using (different tanks weigh different and swing different), and how much weight you needed for the dive in your log. soon, you'll be able to judge and guesstimate pretty close based on your past experiences. there are lots of threads about the 'tank with 500 psi' weight figuring method, and that is the gold standard, but unless you then do every dive in exactly the same suit with the same type tank, you need to re-figure with a low tank again every time something changes. *or* give it a good guess based on what you have written down in your log!

have a great day!

 

[Humuhumunukunukuapua'a]

Sorry to double-post, but if you look at the bottom of the page, you'll see a section called "Similar threads". It's a good way to find out more about a subject. Also the search feature.

 

[Goose75]

The most likely need to ditch weights would be during an emergency at the surface. It will make it easier to get an unconscious victim out of the water. Plus they won't drop like an anchor if you take off their BCD.

Your book should give you information on how to check proper weighting. During your OW class they usually bring extra to help if you take too little. They will probably overweight you at first anyway. Gear configuration, fresh or salt water and the exposure suit will all change what your weighting will be. When I try new gear I bring some extra in small quantities for my buoyancy check.

 

[Blackwood]

There is no formula to follow. It is a function of your weight and geometry as well as your gear's weight and geometry. If you are big, you displace more water -> more buoyant force. If that size is dense muscle, the weight may counteract the buoyancy. If it is fat, it probably won't.

Start with something (PADI says 10% of your body weight, I think*). Add and subtract based on your buoyancy characteristics. If you sink like a rock, you are overweighted. If you can't maintain a 15' safety stop with no air in your BC towards the end of your dive, you are underweighted.



* I don't particularly like this methodology. Rather, I'd start with a little bit of weight and add to it.

If I strapped on 16# (10%) when wearing my singles rig and my HP100, I'd drop faster than I could equalize (I wear 4 pounds on my belt with the aformentioned gear configuration).

 

[Walter]

With no air in your BC, full lungs and a nearly empty tank, you should float at eye level. If you are floating higher, add more weight until you are at eye level. If you are floating lower or sinking, get rid of weight until you are at eye level. If you are weighted with a full AL 80, add 6 lbs.

If you change tank type or have another equipment change (different BC, different wetsuit, etc.), you'll need to reweight.