I just can't sink!

[lrn2dive]

Hi all,

My two boys, husband and I have recently taken PADI OW scuba classes for a trip we're leaving for on Sunday. We've been running into minor bumps and finally need to finish our certification in our vacation destination (Belize), but I have a question. In the pool, I was able to descend just fine, however, we just went out to the lake and I couldn't sink to save my life! The dive shop provided the wetsuit, and it was a brand new suit that I hadn't worn before so one of the shop staff thought that couldn've been part of the problem. My instructor was puzzled; I had enough weights for a 300 pound person (I'm 5'3 an 120 pounds). He thought I was a little nervous and wasn't breathing properly. I think I felt fine and I was really focusing on breathing. All the air was out of my BCD...I even tried to swim down, but couldn't....it was like I was stuck in Jello....couldn't move. Very frustrating for sure, but I'm going to try again in Belize....we don't have the time to finish here.

Any thoughts on what may have been contributing to my problem (one of my boys had no problems, the other had problems initially, but he added more weight and was fine)?

 

[tbone1004]

Depends on how thick the wetsuit was, if you had flooded the suit to remove any residual air in it, how heavy you were breathing etc. At 5'3" and 120, depending on how well endowed you are, you should expect about 6 or so lbs to sink with an AL80. With a 7mm wetsuit, you should expect up to about 12 or so lbs. If you're in a farmer john up that to about 20lbs.

For the record, I'm 280lbs and without a wetsuit I take 2lbs to sink, and in a 7mm I take about 8lbs with an AL80, so it all depends on your body type :-D

 

[mike1010]

Its less about focusing on breathing then just exhaling and waiting a little. Also you may inadvertently be treading water

 

[vladimir]

Some possible reasons include failure to exhale, unintentional kicking, and trapped air. Try crossing your ankles to stop the kicking. Sometimes the timing of the exhale is the issue: you exhale before your bc is fully deflated and are already inhaling when it's time to descend, confounding the process. Make sure the corrugated hose (and the shoulder it is connected to) are higher than the rest of your air cell when venting. Use your arms to squeeze the bc against your body to chase out any pockets of air. Relax on the surface and take your time with all of this. I would expect a new wetsuit to be more buoyant than a well-used one of identical thickness, but the difference shouldn't be as profound as you describe.

 

[DennisH]

You're getting really good advice and vladimir has given a number of possible causes. I had a similar problem to you with one of my BCDs, and I found out that it was trapping a big pocket of air behind my neck even with the deflator properly positioned. Someone on scubaboard very kindly suggested that I try leaning backwards as I deflated the BCD, as if I was in a lounge chair...that freed the air bubble down I went. Let us know what you try, and what finally works for you. And have a great time in Belize!

 

[k ellis]

Definately good advice given. Depending on where the air dump valve is located (Some are on the left shoulder while others are located dead center behind the head) you may have to do some leaning attempt to get that valve to be the highest point. Your not alone in this boat though as I have seen one diver who used a staggering 80 pounds to get them to be negatively buoyant all the while wearing a 7 mil wet suit (I personaly would need maybe 20 - 25 pounds in the same)

How much did you use in the pool with out a wet suit?

 

[spectrum]

Breathing could be part of the problem. You state you're breathing well but initial descent can be a time to break the pattern. Once you vent the BC and sense you are ready to submerge exhale deeply and then exhale some more. You can combine this with a duck dive. With your lower legs out of the water they go from being nearly neutral to dead weight and can drive you down those first few feet. When you need to inhale do so quickly and promptly exhale to minimize your average buoyancy. That may be enough.

Trapped air is possible but the gyrations you describe should have purged that.

What caught my eye is mention of a NEW suit. I assume that the successful pool work was done in a suit of comparable cut and thickness. As suits age the gas bubbles in the neoprene foam become crushed or even broken and the suit slowly looses buoyancy (and warmth) if this is the case then added weight for that suit may be needed.

If it was shop BC make sure no ping pong balls were left in the pockets.

Frankly I'm concerned that the instructor was puzzled. The list of things for him to check is pretty short before deciding to add a little weight.

In Belize you won't have early as much neoprene to deal with and will be in the ocean. you will all need to completely redefine your weighting configuration. Be sure he covers this fully. This may also be helpful.

Congratulations on embarking on this family adventure, that's very cool.

Pete

 

[MXGratefulDiver]

It's a common problem with OW students ... and one that's usually easily fixable. Vladimir described the reasons for it pretty well.

Most new divers can't sink because they're fighting against a hard-wired instinct that's trying to keep your head above water. Your body's reacting in ways you may not be aware of ... so let's make you aware of them by telling you what to think about as you're trying to descend.

When you're ready to descend, get vertical, hold your inflator hose up, and take a deep inhale. Now, hold it as you press the exhaust button to deflate your BCD.

Don't start breathing out until your BCD's almost empty ... about the time you get to be eye level with the surface. Now start a long, slow exhale.

Keep exhaling as you finish letting all the air out of your BCD. Just about the time you think you've got all the air out of your lungs, exhale some more ... you'll probably be surprised to realize that there's still a lot of air in there.

Think of your lungs as just another BCD ... you have to let all the air out in order to sink.

By the time you finish exhaling, you should be a few feet underwater ... where pressure is your friend, compressing your wetsuit to make you even less buoyant. The thing to keep in mind is that if you breathe in while you're too close to the surface, you're "inflating" your internal BCD, which is going to send you up while you're trying to go down.

Now, while that's all taking place, what are your feet doing? A lot of times, the new diver is kicking without even realizing it ... once again, you're sending yourself up while you're trying to go down. Try crossing your feet at the ankles ... it won't stop you from kicking, but it will make you aware that you're doing it so you can make a conscious effort not to.

Once you're down a few feet, have completely exhaled, and are beginning to inhale, now uncross your ankles, bend your knees, and point your fins back. The downward motion of your body as you descend will push slightly against the tops of your fins ... gently and naturally moving you into a horizontal position facing the bottom. As you move into that position, straighten your legs and assume the "skydiver" position ... don't forget to watch your buddy as you go ... they should be doing the same thing you're doing, and this is an important time to keep an eye out for difficulties. If at any point in the descent you need to stop, just take a deep breath ... inflating your "internal BCD" will help arrest your descent. As you need to breathe out, put a couple quick puffs of air into your external BCD to replace the air you're breathing out.

This is also how you should manage a stop as you approach the bottom ... so that you don't have to rely on hitting the bottom to stop your descent.

Generally speaking, the reason most new divers use too much weight is because they have difficulties on the descent. By identifying and resolving the reasons why, you will usually be surprised at how much weight you're carrying around that you don't really need. Take it off in small quantities as you get more relaxed and comfortable with your descent techniques ... this will come over the course of a few dives if you work at it.

Hope that's helpful ...

... Bob (Grateful Diver)

 

[a22shady]

I can only think that in the pool you were probably only using a 3mil suit and if your lake is cold then you should have swutched into a 7mil. If that is the case then you infact would need to add more weight as the thicker the suit the more weight needed. The one thing about scuba for each piece of gear you add (Clothing) you will need to add more weight to compensate. If you only add hood or boots might not notice big difference but always good to do a bouyancy check. Also as the others were stating above Make sure your lifiting the deflator hose and holding it high abovee your head, Sometime you need to pull it up straight as air can get stuck in the hose if it's not. Also try to leaning to the opposite side that the infator is on. Make sure your exhaling slowly once your air is coming out to help you begin to decend and try to take a nice slow breath untill your under. Try to make sure your not kicking a lot of people do this and not realize.

 

[Diver71_au]

All good advice but just a word of caution on adding more and more weight.
Firstly this is not good practice as it means that you will waste more air in maintaining neutral buoyancy when you do get below the surface.
Secondly by adding more weight to a belt you screw up your trim - the weight belt is pulling your lower body down and the BCD (which is inflated at depth to offset the extra weight on the belt) is pulling your torso up. This body positioning often then leads to the diver believing they need more weight as the body position they assume means that as they swim forward the position of the body causes the diver to swim toward the surface due to the flow of water (much as the angle of a plane's wing flaps control the ascent or descent).

The main thing to remember is exhale fully and slowly, fully deflate the BCD (play with positioning to ensure bubble that are trapped get released), and dont kick - some have suggested crossing the ankles, personally I like to get my students to do this AND point their toes so that the fins are pointing down - not horizontal.