Stupid bouyancy question

[jbd]

will have weights for their customers to use. A good DM will be able to make a good estimate of what you will need in salt water if you know what weight you need in fresh water. Of course you probably won't being wearing the same exposure protection so that will change things also.

Entry into the water you will most likely have your BC partially inflated. On the siganl to descend you let air out of the BC until you are floating at eye level as others have explained. At this point you are considered neutrally bouyant. Simply exhaling will start a slow descent.

If time and conditions warrant it, then you could consider purging the air from the tank until its down to 500 psi at the end of your safety stop. Make sure your BC is completely deflated and that you are totally relaxed and motionless. If you sink your are overweighted. If you ascend then you are underweighted.

Before doing this, make sure the DM and your buddy know what you are going to do before you get in the water.

In response to rollins--sounds to me like you are slightly overweighted and not quite properly trimmed.

 

[SubMariner]

Until you have a lot of dives under your belt (pun intended) you will probably have to do a bouyancy check fairly frequently. Then several things kick in:

1) You relax when diving, establishing a better, more efficient breathing pattern. This usually means shedding some weight because you won't be "holding" so much air in your lungs all the time.

2) You dive in a variety of conditions with various exposure protections. And you LOG the dives so you know what weights you wore and when. So, instead of doing a bouyancy check before doing the Black Bart in the Gulf, you simply look it up in your logbook & see what you wore the last time you dove there.

3) You decide to get a steel tank and take some weight off the rest of your weighting system.

DSDO,

~SubMariner~

 

[rollins]

Thanks for the tips, great discussion...

 

[drbill]

I have been unpleasantly surprised, and concerned, as I watch divers enter the water at Catalina's Casino Dive Park. Many times local instructors and I have commented on how over-weighted many seem to be. Such a situation can lead to serious problems if one must ditch a weight belt at depth and ascend too quickly.

Just last weekend we experienced a diver who ditched their belt and ascended too quickly. Fortunately they showed no sign of symptoms.

As a videographer, I always overweight myself to ensure greater stability when filming on the bottom. However, I don't place all my weight on my belt. That way I have weiughts that are easily ditched if need be, yet retain sufficient weight to prevent a rapid ascent.

Dr. Bill