Buoyancy Issues

[spectrum]

A.) I think the OP is MUCH better off with the instructor that he has, compared to the majority of numb-nutz instructors that espouse the "overweight yourself in the beginning" philosophy. Most instructors I see running classes blindly hand everyone 20lbs of lead and look more like they are runninng "Discover Silting" or "Intro To Reef Destruction" than OW.

You said that much better than the paragraph I had drafted for my response!

 

[Dive Right In Scuba]

A.) I think the OP is MUCH better off with the instructor that he has - all other things considered equal - compared to the majority of numb-nutz instructors that espouse the "overweight yourself in the beginning" philosophy. Most instructors I see running classes blindly hand everyone 20lbs of lead and look more like they are runninng "Discover Silting" or "Intro To Reef Destruction" than OW.

quote]

I agree that you shouldnt overweight them to the point of "Discover sitting" etc, but nobody said give them 20 more lbs than they need. A new diver should safely have a couple more pounds with them so they can compensate with their BC to start to learn bouyancy.......as they LEARN they can remove and start to trim up their weight....Lets remember these are new divers in a shallow pool, with experience comes better bouyancy, and during fin pivots in a pool is not the time to want your students floating away......2 more lbs. or a set or ankle weights is not goint to be teaching Intro to Reef Destruction......its going to get them more comfortable with the skill they should be learning and then practicing to perfection.....which leads to the excellent bouyancy.......Im honestly surprised at some of the responses....New students breath alot more because they are uncomfortable and its hard to adjust....while they get comfortable and adapt to the new world of underwater, why not keep them done with an extra pound or two so they can enjoy it....and as they get comfortable start trimming weight. We consistently have students drop anywhere from 4-6 lbs. and they arent wearing alot more than they need, but enough to keep them down for the skills, then we work on bouyancy and do the same skills in a deep well( Thanks local HS dive team) while hovering.....

 

[Damselfish]

There's no replacement for doing a weight check. It's often more convienient to do it with a full tank, just add the amount of air you might breath (typically 5-6# on an AL80.)

It's hard to get it exactly right at first. And it's better to be a little (not a lot) overweighted than underweighted. You can compensate for overweight with your BC but you can't compensate for underweight. And when you're new you may tend to hold air in your lungs, not get all the air out of your BC, stuff like that. I think sometimes so much emphasis is put on dropping weight that new divers may try a little too hard and overdo it.

 

[Jasonmh]

Hi Mike,

Everyone has trouble with buoyancy until they have a few dives under their belt.

I agree with alot of what has been said here. But also, don't worry too much about it. It is good that you are concerned about buoyancy, but it does take some time and practice. Everyone is different, and you can't really expect to perform to the same level as the people who were doing their refreshers. I have a pretty good handle on my buoyancy now, but when I first started I had a really hard time with it. My instructor pulled me aside during the OW checkout dives and told me that I probably wouldn't pass unless I had a huge improvement in my buoyancy.
Also, sometimes when you are new at this, people have a tendency to breathe of the top of their lungs when underwater. In other words, there can be the thought that "what if I breathe out and then can't get another breath", so people don't really breathe all the way out. Instead they take a FULL breath, then breathe out maybe 10-25% of that, then breathe right back to FULL again. That can mess with your bouyancy too. If you are lying on the bottom of the pool and have no air in your BC, and are taking slow, deep breaths, and you still can't stay on the bottom, then you are slightly underweighted. The weight checks at the surface can get you close, but they are by no means a dead-on number for your weighting under all circumstances. People can overcome a serveral pound weight difference with just their lungs.
Anyway, you will get it, don't give up and don't worry too much about keeping up with anyone else. It is a personal thing, for some people it takes 5-10 dives, for others it might be 20-40, but you will get there.

Good Luck,
Jason

 

[Peter Guy]

While I agree whole heartedly with PF regarding the worthiness (or lack thereof) of the fin-pivot, I submit most of you have jumped over the OP's problem which is being able to do a fin-pivot so he can get on to learning what bouyancy control really is all about!

When I was taught the fin-pivot I found I had a very hard time doing them in my split fins -- fins that almost everyone had. I'm now doing a DM course and my partner and I were playing around with fin-pivots the other night in the pool. She had a very hard time keeping her feet on the bottom -- mine just sat there. She had very light fins of some brand, I had 40 year old Jets WHICH ARE QUITE NEGATIVE. We then switched fins and guess what -- her feet also became rock solid.

So, for those people who do have problems with that silly fin-pivot task -- perhaps you should think about getting some weight on your feet (Jets or (gasp) ankle weights). At least you'll be able to do the task and, perhaps, you'll also learn how you can adjust your bouyancy with breath control (which, I believe, is the goal of that stupid task).

BTW, at my next meeting with my DM instructor, I'm going to ask him about foregoing kneeling and, instead, lying on the bottom of the pool to do the various tasks. (Off topic but ---) One of my pet peeves in watching people get taught mask flood skills is watching them do it kneeling -- which, when they tilt their head up almost always tilt their body back! This, of course, has the tendency to put their nose in a position to be the exit point for the water which means when they try to clear the flood they are blowing water into their nose and down into their throat.

 

[PerroneFord]

actually i rememeber alot of tours with newer divers where i helped them underwater with there buoyancy or trim in the upright position..


i dont really want to argue with anyone.. the best thing is to understand what your doing.. and the rest will follow...

Understood on the arguing. My question was really one of curiosity. In helping newer divers, I generally keep my horizontal trim position. So it was curious to me when you said you were hovering vertical.

If that's how you choose to do it.. then cool. Now I understand.

 

[SparticleBrane]

...what the heck is a 'fin pivot'? I've never heard of it.
Is this something close to a helicopter turn? I'm guessing it isn't...

 

[ae3753]

The eye level float method of weight checking (which is a good) needs to be done with a near empty cylinder to get it right. In your cases you must have done it at the onset of the class and would need to add an additional 5-6 pounds of weight.

You probably had 80 CF cylinders. Lets say you intended to consume 70 CF of air. Air weighs .08 pounds per CF. 70 X 08 = 5.6 pounds of weight you will loose during the dive. You can see that before long you will be getting downright buoyant without that extra 5-6 pounds.

It's always best to repeat the test at the end of the dive (or pool session) since early in the dive you can have a pound or 2 of stowaway buoyancy in the form of air trapped in padding, fabrics and such. In any event you are much safer diving a pound or 2 heavy that being a little light.

Not too many things are as frustrating as being under weighted and to be so while cutting your teeth must have been a pain. While it would have been nice if your instructor had caught on and helped you have a more productive session at least he (she) did not blindly overweight you two.

...

Have a great time competing your certification and on the vacation. Remember... we all expect to hear a full report.

Great post, agree 100%.

To the original poster: If I am properly weighted on a dive, it is nearly impossible for me to kneel on the pool bottom.

Absolutely. Being weighted properly and doing skills firmly planted on the bottom of the pool do not mix. As Dive Right In Scuba recommends, I find that adding 2# is enough for me to be comfortable. Adding 4#s will plant me firmly in place.

So, for those people who do have problems with that silly fin-pivot task -- perhaps you should think about getting some weight on your feet (Jets or (gasp) ankle weights). At least you'll be able to do the task and, perhaps, you'll also learn how you can adjust your bouyancy with breath control (which, I believe, is the goal of that stupid task).

I waver back and forth on the value fin pivot. Anyways, here's my fin pivot tip:

If are weighted for horizontal trim, then angle your fins perpendicular to your body when you need to fin pivot.

A lot of people attempt fin pivot with the fins angled all the way back, as in swimming position. If you do it this way, you are trying to touch the top of your fins to the bottom of the pool. For this to work, your feet have to be more negatively weighted than the rest of your body.

However, if you angle the fins perpendicular to your body, you trying to touch the point of the fin to the bottom of the pool. This can be done when you're weighted for horizontal trim.

If you have floaty feet and can't get in horizontal trim, then you'll need Peter's recommendation first.

 

[deepblueme]

""I can say without question, that at no time, on any dive, did I ever have a need to hover upright. When do you find this skill helpful?""

Wall diving, saftey stops, drift diving, blue water diving are all the times when I would use "upright hovering".
About the only time I would use horizontal hovering is when diving on a flat bottom.

My need for "over weighting" students comes from, How do you teach someone to use a bcd inflator if they are netural? adding 4-6 lbs and explaining to them why then removing it I found works the best for me when teaching the fin pivot and hovering skills.
It also simulates what happens when you are wearing a wetsuit at depth swimming from shallow to deep when wearing 10 extra pounds, the problem is when the Inst. doesnt tell the students the reason for being over weighted in the first place.

 

[SparticleBrane]

"upright hovering" is actually more difficult than hovering in good trim. Being horizontal shows a larger surface area to the water, making changes in depth more difficult. How many time have we all seen people 'standing up' underwater, having to kick to stay up? Showing a much smaller surface area to the water makes it much harder to stay in one spot in the water column.

There are plenty of ways to show people how to use the inflator without overweighting them. Deflate at the surface to drop down, use it during the dive to maintain neutral buoyancy after descending. Use your rear dump valve to deflate. Easy as that.