Does a BC filled to capacity maintanin a constent amount of lift at different depth's

[pipedope]

As you go deeper and the water does not compress to any significant degree at depths we dive.

Now, remember that the 77.4 cuFt of air in an AL80 weighs about 6 pounds. If your BC has about 64 pounds of lift (one cuFt in sea water) then at the surface it would have about 0.08 pounds of air at the surface if full. Now if you dive to 5 ATM (about 130 feet in sea water) then the BC would have about 0.4 pounds of air in it if full.

Not a big difference.

BTW Has anybody here ever needed to FILL their BC at 130'?

 

[Cave Diver]

Next; how many pieces can you split a hair into?

I dont know, but I bet you cant fold a single sheet of paper in half more than 7 times... :54:

 

[FredT]

BTW Has anybody here ever needed to FILL their BC at 130'?

Yep.

FT

 

[GSmith]

This thread has been running in parellel with this one under /Equipment/BC's and Weight systems titled: Anyone using the 18# Oxycheq Wing?

Doc Intrepid sent me a message bringing to light the risk of down-dwelling currents, which I have in part posted here: http://www.scubaboard.com/showpost.php?p=503957&postcount=10

I hope you don't mind me posting it Doc!? I was not giving it due consideration.

I've got to put an inline guage on my BC to check this question out further. Are the pressures really that low Pipedope?

FredT- Were you trying to lift something that warranted filling your BC at 130'?

My previous assumption about the OPV being able to maintain 150 PSI seems to be in left field. But what is the number that it releases at and interms of depth?

Greg
Greg

 

[Cave Diver]

FredT- Were you trying to lift something that warranted filling your BC at 130'?

I give FredT much more credit than that. I believe the object he was trying to lift was himself.

 

[Scubaroo]

Greg,

If I'm reading your post correctly, Fred doesn't mean that the BC contains 0.4psi - he means 0.4 actual pounds of air. Weight, not pressure.

Ben

 

[Snowbear]

FredT- Were you trying to lift something that warranted filling your BC at 130'?

I think he was referencing the spearfishing/bristleworm incident?

 

[FredT]

FredT- Were you trying to lift something that warranted filling your BC at 130'?

My previous assumption about the OPV being able to maintain 150 PSI seems to be in left field. But what is the number that it releases at and interms of depth?

It's happened several times. Here is the latest post of one incident. :54:

http://www.scubaboard.com/showthread.php?p=76668#post76668

Remember that the OPV works on the delta of pressure across it, not the absolute pressure on the diver.

FT

 

[pipedope]

Yep.

FT

OK, FredT, I know your bristle worm story. WOW!
Give me a nice, safe pipe anyday, that spearing fish thing is *dangerous*.

 

[donacheson]

As you go deeper and the water does not compress to any significant degree at depths we dive.

Now, remember that the 77.4 cuFt of air in an AL80 weighs about 6 pounds. If your BC has about 64 pounds of lift (one cuFt in sea water) then at the surface it would have about 0.08 pounds of air at the surface if full. Now if you dive to 5 ATM (about 130 feet in sea water) then the BC would have about 0.4 pounds of air in it if full.

Not a big difference.

BTW Has anybody here ever needed to FILL their BC at 130'?

Not quite full, but I once did recover about 28 pounds of abandoned weightbelt and weights from close to that depth. Probably it was a dry suit diver who dropped it; I've always wondered what terminal velocity he/she reached on the way up. <G>