How much weight do I need ?

[Saloooh91]

Hey everyone. So today I started my first open water swimming in pool class and I had to put some weight. The trainer told me put what ever makes you comfortable. I've put two big and two small weights on the belt. ( I don't know know how many kilos/pounds they were) I started to sink fast even when I put air in the PCD.

I weigh 255 lbs/ 116 kilos

How much weight do I need in order to be in a good position instead of sinking in the water.

Regards,
Salah

 

[Saloooh91]

BCD*

 

[John B Griffith Jr]

So, a few things here...your instructor did not give you the best advice. It is critical that you know exactly what amount of weight you need to comfortably get to a negative buoyancy state at the surface...you have to be able to sink. The trick is to not have so much weight that you are having to use too much air in your BCD to counteract it. So factors you must address and take note of: Exposure protection, are you wearing a wetsuit? What thickness? This will change the weight requirements...so make a note...I would write down that "in a 3mm wetsuit in fresh water, with a full, 80 cf aluminum cylinder, with XYZ BCD, mask, fins, gloves, hood, etc...I need 16 pounds (for example) of weight to sink with my BCD fully deflated and when I exhale. In salt water, I need 18 pounds.

Each thing you add or subtract makes a difference. But the test is...how much weight do you need to sink below the surface gently when you exhale, but can stay on the surface when you inhale/breath normally. Over-weighting is a prime cause of wasted air, fatigue, poor trip, bouncing all over the water column, failure to master skills, etc.

Make sure that you study some of the many videos and articles available on properly weighting out for diving and you will have a much better experience!

 

[psimian]

My procedure for determining weight is this:

At the surface, with a full tank of air and a completely empty BC you should be able to do a relaxed exhale and remain just barely positive (floating with only the very top of your head out of the water). If you forcefully exhale you should start to sink. If you are diving with an Aluminum 80 tank, add 4 lbs to account for the extra buoyancy of the tank when it is empty. Your ultimate goal is to be able to be neutrally buoyant at 5m (15') with a nearly empty tank, since this is the worst case scenario for you doing your safety stop at the end of your dive. You'll probably want to add a few extra pounds at first; as you get more comfortable controlling your buoyancy through breathing you can get rid of this extra weight.

Average lung vital capacity (how much you can voluntarily inhale/exhale) is around 3L, which translates to 3kg (6.5lbs) of buoyancy that you can control just by breathing. It's pretty easy to switch between breathing with the upper half of your lungs (Full inhale, neutral exhale) and the lower half (Full exhale, neutral inhale). If you start to rise unexpectedly, empty your lungs completely--you can go for a 15-30 seconds on empty lungs under the worst of circumstances, more than enough time to get your buoyancy sorted out. Conversely, if you start to sink, take a deep breath. In general you should never hold your breath on SCUBA, but as long as you are descending you don't have to worry about rupturing your alveoli.

 

[Woohoo]

It is critical that you know exactly what amount of weight you need to comfortably get to a negative buoyancy state at the surface...you have to be able to sink.

Is this the same for free diving/spearfishing? I'm having a problem with this right now. The weight I'm using isn't enough to make me neutrally buoyant under the water. If I stop swimming I'll fairly quickly return to the surface.

BUT... If I stop swimming at the surface for just a few seconds the weight starts to drag me under and I get a lung full of water through my snorkel. I'm loathed to put even more weight on because that getting dragged down and choking on sea water feeling doesn't work for me, yet I want to stop swimming and stay perfectly still when I'm under water.

Is it literally a case of you can't have one without the other? Do spearos never stop swimming for any length of time? Or is there something else I'm totally missing?

Any thoughts appreciated.

 

[psimian]

For free diving I weight myself so that I can be neutral at my target depth if I start with half a breath of air. This let's me be buoyant enough to float at the surface. If I'm going deeper I start with a bigger breath, shallower and I take a smaller breath. This works pretty well down to 15-20m; below that you're probably going to sink no matter what due to the reduced volume of air in your lungs.

You should definitely be positive for the first 5m, possibly even to 10m for safety's sake. Since you aren't wearing a BC, you have no way to adjust your buoyancy on the fly and there will only be one particular depth where you are neutral. Above that point you float, below it you sink.

 

[pete26]

A proper weight check should be done with an nearly empty tank not full one!

 

[DiveMe]

Hmm..... one of basic skills which you have to do on your open water course is "weight check". Your instructor have to teach you how to set proper weights.


---------------
Savicky.pro - Your Diving Instructor in Thailand

 

[Blayze H.]

Hey everyone. So today I started my first open water swimming in pool class and I had to put some weight. The trainer told me put what ever makes you comfortable. I've put two big and two small weights on the belt. ( I don't know know how many kilos/pounds they were) I started to sink fast even when I put air in the PCD.

I weigh 255 lbs/ 116 kilos

How much weight do I need in order to be in a good position instead of sinking in the water.

Regards,
Salah

I had an internship at a dive center over the summer, and I found that an important thing to note is that weights needed when diving/training in the pool are relatively lighter than the amount of weight you would need in a salt water dive. This is because salt water is much denser than fresh(or pool) water. Also, with more experience you will find that you can begin to use less weight in your diving. I weigh about 170 lbs, and at the beginning of the summer I used 14-16 lbs. Towards the end I was able to use 2 lbs or 4 lbs when diving with customers(in case of emergency). The weight you need will also be based on your body type, muscle-fat ratio, whether or not you are using a wet-suit, the thickness/length of your wet-suit, etc. It would probably be best to inquire with your instructor or any local diving professional about this.

 

[Graveyard Diver]

I found this to be right on the money for me. I actually took off one pound to get it "just right", but that was within their +/- one pound error factor.

http://www.divebuddy.com/calculator/weight.aspx