Bouyancy/Weight Problems

I saw a similar posting in this category, but my problem is a little different....

I'm a new diver (13 dives). It was suggested by my LDS, that based on my weight, I should start with 20 lbs. I recently bought a Dive Rite BC, with a rec wing and integrated weight system. They put 8 lbs. on the tank straps, and 6 lbs in each pocket, totalling 20 lbs.

I'm 5'10 and weigh 195 lbs. I'm in decent shape, with some "love handles"

The first day using my new equipment:

On the first dive, the problem I had is that I didn''t sink, and had a hard time going to the bottom. I had to go head-first and swim down.

On the second dive, I added 4 lbs. (totaling 24 lbs) and I still didn't go down very easy. Once I was down, I could stay down, with a little air in the bc. When coming up, I would dump the air, and swim up slowly to do my 15 ft, 3 minute safety stop. As I got higher, approaching 15 feet, I would start floating up, and had to struggle to stay at 15 feet.

On the third dive, I dumped 2 lbs and went to 22. Didn't make much difference, either way. I had the same problem at around 15 feet.

I went back to the LDS and the guy suggested that I bump up my weight to 26 lbs, and it sounds like a lot..... Does that make sense?

I would really appreciate some input...

Are you wearing a drysuit or wetsuit.If it is a wetsuit what thickness is it and is it fairly new.Also what type of tank are you using and are you diving salt or fresh water.

Wearing a Henderson Goldcore 7/5 mm wetsuit. New, first time in the water.

I was wearing a 80cf Aluminum Tank

Diving cold, salt water (55 degrees)

You need to do a weight check in the water. You may want to do it with an empty tank (preferred method I learned through the board).

There are several posts here explaining the various methods. Don't forget to add the equivalent weight of the air you will use so that you're neutrally buoyant at the end of your dive (and can sink at the beginning).

You also may want to change your wing. You don't need 51 lbs of lift with an Al80 and you may not fully empty it before sinking.

99heritage once bubbled...
Wearing a Henderson Goldcore 7/5 mm wetsuit. New, first time in the water.

I was wearing a 80cf Aluminum Tank

Diving cold, salt water (55 degrees)

Click to expand...

Your probably gonna need a little extra weight till your wetsuit settles.Most new wetsuits are extremely buoyant till they compress a little bit.That will come with time and some deeper diving to compress the suit.

Your tank has about a 5lb swing from full to near empty so when you go from the surface to submerge as you descend your gonna have to add air to your bc to offset the weight of the full tank and as you descend your wetsuit compresses and loses buoyancy which means you have to add more air to your bc to offset that effect.

As you do your dive your using air out of your tank which means it gets more buoyant and also means less air in your bc cause your tank is getting lighter.Your goal is to be neutral at the end of your dive with about 500 psi in your tank at 10-15ft so you can perform a safety stop.

Also remember your breathing has a big affect on your buoyancy.When you breathe in you tend to rise and as you exhale you tend to sink. If i remember right a full set of lungs can produce 5-8lbs of lift.

A couple of tips for descending are

Cross your legs so you are not inadvertantly finning and not realizing it

Make sure you get all of the air out of your bc

you may want to pull the neck of your wetsuit open to burp any air out

As you get ready to descend breathe out completely to help you sink those first few feet.

Make sure you are weighted properly.You should only be negative at the surface by the weight of the air in your tank which is right around 5lbs

Till your wetsuit compresses slightly and wears in, the first few feet may be tough to get under till the wetsuiit starts to compress slightly and lose its bouyancy.

I would say slightly over weight yourself at around 26-28lbs and check your buoyancy at the end of your dive at 10ft with 500 psi with no air in your bc.If you sink remove a few pounds at a time till you remain neutral at 10ft.After your wetsuit settles you will be able to remove slightly more weight.As you dive more and learn to relax underwater and not be all stiff and rigid you will lose moreweight.As you learn to breathe under water such as using the bottom half of your lungs and the top half you will lose more weight.I would say ideally you will probably be right at 20lbs of weight after you settle in.

Then once your buoyancy is correct you get to work on your trim.I hope this helps

All the above advise is righ on. A ROUGH guess based on what you have said about your height, weight and equipment, weight in the mid 20's range sounds about right, esp for a new diver. Best advise is to do the bouyancy checks, accept the result and dive. The use of an empty tank (or add about 5 lbs if you must use a full tank) is very important. You will find as you get more comfortable in the water and your wetsuits compresses some you will need less. I would also suggest that you write down in your log your exact equipment, weight and how you felt about your bouyancy (good/too much or too little weight) at the end of every dive, esp in the beginning. The next time you encounter a similar dive, you have a reference to go by. Bouyancy checks are very useful, I still do them at the end of most dives if I have the oppertunity to help fine tune my bouyancy.....and log the result.

I agree with Arnaud. An in water weight check is the way to go.

After a dive, at around 10 feet, keep handing off weights to your buddy until you are neutral with no air in your BC. Remember how much weight you gave your buddy and keep it off permenantly.

You'll need a pocket belt or some integrated weight system where you can remove individual weights in order to be able to do this.

It might sound crazy and unscientific but one of the things a new diver has to do is learn to relax. Some how the sinking difference between a relaxed limp diver and a tense one can be in excess of 8lb. Take time out on surface before you descend to regulate your breathing until its nice and slow and relax the body and when you exhale you should find you sink a lot easier.