FrenchFrog:
Here it goes:
I'm still trying to adjust my buoyancy and here are my problems:
Equipment: SP glide star BC, 3mm wetsuit, I have 4 pounds of weight in each ditchable pocket and 1.5 in each non-ditchable in the back.
I still feel too heavy at 100 feet but can barely stay at 15 feet at the end of the dive (aluminium tank 80). Learned to dive with steel tank and miss them greatly !!!!
Also my legs and ankles tend to float, can't stay horizontal by the end of the dive.
My AOW instructor kept telling me you need to relax and your legs will go down. The problem is I wasn't stressed a bit, nothing stressful in taking pictures of fish, slugs, ect.. on the contrary, life could not be better. I think it is a girl thing versus a guy thing (meaning body shape and floatation, you know !!!
, I have a typical girl figure). It does not seem like I can remove more weight so what do I do ???
Add weights at the bottom of the tank ?? Wear some ankle weights (never seen that discussed before). Thanks for your suggestions
FrenchFrog
I'll take a crack at it. First, don't get discouraged. Buoyancy is one of the hardest skills to master, and is the thing you'll see divers having the most problem with on any given dive boat.
First the change in buoyancy you describe from 15 ft to 100 ft is normal. Even if you were so buoyant you had to pull yourself down the anchor rope, at 100 ft you would probably be putting air in your BC to keep from being negative. That's normal. As you descend, pressure squeezes all the excess and trapped air out of your wet suit, BC etc.
Couple of questions: Did you do "fin-pivot" excercises in the pool? And did you master them? Fin pivots teach students that their own breathing changes their buoyancy dramatically even if they have the proper amount of weight. With fin pivots, while lying on your stomach on the pool bottom, you take a deep breath and you float off the bottom -- exhale and you sink. Your fin tips should be the pivot point and stay on the bottom of the pool.
If you mastered this excercise in the pool, put it into practice on the bottom. First, dump all air from your BC as you go underwater. I know they teach students to fill their bc before going over the side, but I don't do this. I pull every ounce of air out of my bc before rolling over. I even put the inflator in my mouth and suck out as much air as I can, so that I have next to nothing in it when I hit the water. Don't do this if you are not sure that you've checked your gear and you know its working or if you don't feel like you could handle an emergency.
You should be bumping your inflator on the way down to 100 ft to compensate for your lost buoyancy due to depth. When you get close to the bottom, you should be able to inhale and begin to rise and exhale and sink. If you still sink when you inhale, you are too heavy -- add some air but just a bump; if you still rise when you exhale, dump some air, but again-- just a bump. Many divers add a lot of air then dump a lot of air. Try to add little bumps from your inflator until you feel just right.
It will take you a while to get comfortable with this skill, but when you do, you'll notice that you use your breathing as your buoyancy control. When this is mastered, it saves you a lot of air because you do less swimming. I spearfish on big wrecks with lots of relief off the bottom. I can take a deep breath then give a long exhale and drop 12 ft down the side of a barge without doing any swimming. Try to consciously practice this skill and it will make your diving much more enjoyable. Also, deep breathing not only helps buoyancy control but saves air in and of itself. If you are taking shallow breaths, that could be making it harder to maintain buoyancy.
Also, if you did fin pivot excercises with a steel tank in fresh water, it would be much different with an aluminum tank in salt water. Salt water is more buoyant than fresh and the aluminum 80 adds about 4 pounds of positive buoyancy to you at the end of the dive when you least need it. That means that even if you got in the water and were slightly negative, you would be positive at the end of the dive. You can take an empty aluminum 80 and throw it in the water. It will float.
Right off the bat, it looks to me like you just don't have enough weight for your set up. If I caluated right, you have 11 pounds -- two 4 pounders and two 1.5 pounders. You didn't tell me how much you weighed, but of course, the more body fat we have, the more weight we need, and yes women have more than men.
Unfortunately, there are only two options. Add more weight or reduce your buoyancy. The good news is that you can both add weight and reduce buoyancy by going steel with your tank. If you really want to keep diving and enjoy it, invest in a steel tank.
The other option is ditch the 3 mm. If the water is warm enough, try diving with a skin like a PolarTec or go to a shorty. In the summer in Pensacola, I dive with a skin, a steel tank, a steel back plate with wings bc and 6 pounds of lead in my backpack. That's all I use. I don't even use a weight belt, and I am 230 lbs with more body fat than I should have.
When I put on the wet suit, I have to add a bunch of weight, so I try not to use it unless I really need to. You don't want to be uncomfortable, and lots of times you'll make the first dive only to find yourself cold on the second because you've lost body heat. If you need the 3 mm to stay warm, find another way to compensate but if you can do without it, that will help tremendousely.
As far as the staying horizontal thing, I think I have to agree with your instructor. Your legs should be one of the least buoyant parts of your body. Legs are mostly muscle even in overweight people, and if you have a "typical girl figure" your legs should be the least buoyant part of your body. Think about it. When your in the water without gear on, what floats? Your torso is much more buoyant than your legs. I hate the idea of adding more weight, so I would do it sparingly and as a last resort. If you need it, you need it, but you only want as much as you absolutely need.
What I would do, if I were you is try some different configurations, try to use your breath for buoyancy control just like the fin pivot excercise, and keep a good log book. Record every variation and the result. For example "dove with a skin, Al 80 and 12 pounds weigth -- was able to hang at 15 ft with no problem, but noticed I started to get cold -- may need a shorty..."
That is the beauty of logging dives. After doing that for a dozen or so dives, I promise, you will forget you ever had a problem.
Keep in touch and let us know how you're progressing.
