Back Inflate Vs. Jacket Style!!

[radinator]

I agree with Web Monkey. Too much weight means too much air in the BC to compensate. Then every time you ascend or descend, Boyle's Law makes that (too much) air expand and contract, and you gets lots of buoyancy changes. Much more than if you were properly weighted.

The end result is what you describe. Hitting the bottom or hitting the surface. A yo-yo dive.

Out of curiosity, what was your exposure suit and hw much weight did you have? Also, what is your body makeup? This can only give us a ballpark idea of your buoyancy, since each person is different and it depends a lot on your body makeup. However, I am curious if we might see something blatently out of whack.

 

[memon1]

THANKS FOR THE INPUT!! RADINATOR I believe that I had around 30 w/ a Henderson Gold Core 7mm farmer john. I am 190, and 5'10. Thanks in advance for any help you can provide!!

 

[Fish_Whisperer]

Mick, I am 5'10", and 180 lbs. In a 5mm wetsuit, I use 16lbs. I don't know how much more weight you would require with two millimeters more neoprene, but thirty pounds seems like an awful lot...

 

[Damselfish]

Farmer John I assume means 2-7mm layers on the torso - and a newer suit? And the 5mm is a single layer - with more miles on it? Are these in fresh or salt water? It can get hard to guess weight by comparing with someone who may not even have the same body composition over the net, really need to do a proper weight check. (Without holding excess air in the lungs, making sure the BC is really emptied, and without unconciously finning.)

I'm guessing you weren't very relaxed while all this was going on either, which wouldn't have helped.

 

[Lead_carrier]

HEY ALL!!
I just got my AOW this weekend, and after not diving for about 2 years it was different!! I was using a back inflate DUI I picked up for cheap, .....

Did you happen to do an update prior to getting AOW or was that one of the specialties? Personally, if I had been out of the water that long I would have insisted that one of the specialties be the bouyancy class. ( or ask for a refund). The instructor should have addressed and helped you with this, even if the bouyancy class wasn't included.

I agree alot with with what has been said about your being overweighted. You can't use the charts as gospel. I'm 5'10, 200 and don't wear but 14# with a 7 mil.

 

[memon1]

Lead, I got the PPB class included w/ the advanced, and I got an update before I took the class as well. Yeah, I guess my prob was probably being overweighted. Thanks for the input everyone!!!

 

[Lead_carrier]

Lead, I got the PPB class included w/ the advanced, and I got an update before I took the class as well. Yeah, I guess my prob was probably being overweighted. Thanks for the input everyone!!!

The PPB class should have covered the yo-yo dive. If you are still questioning why you couldn't get down or why you popped to the surface, make the instructor re-do the class with you. Doesn't sound like the subject matter was covered very well or the principals put into practice.

 

[Fish_Whisperer]

Good luck, Memon. I'll bet that once you get your weighting corrected, you'll like the cleaner profile of the back inflate. I love mine and wouldn't trade it for anything.

 

[oceancrest67]

I used a jacket style bc when I firs started diving 12 year ago. Now, I use a Dive Rite Transpac (back inflate and good for single tank diving). I also use a BP / Wing set up for my doubles etc. BP / W is the way to go even with single tanks...just get the adapters. Also...a crotch strap is a great item to keep the whole unit glued to your back. No shifting. Jacket style BC's tend to ride up and shift all over...nonsense in my O2.

 

[spectrum]

It sounds like you needed a refesher before AOW.

Like anything else fit is everything but what you describe sounds like rusty watermanship and buoyancy control.

Did the instuctor review your gear configuration before your dives?

If you try to bob high in heavy seas a very inflated back inflate may tip your forward especially with a near empty aluminum cylinder on your back.

I dive a Sherwood Avid, I tried some back inflate BCs in pools and liked them well enough. There may be a plate and wing in my future but it's not a burning need.

A BC style will not make the diver but a poor fit will mess him up.

Pete