Why will a diver become less buoyant as he swims deeper?

[meekal]

is being asked over on

http://www.faqfarm.com/Q/Why_will_a_diver_become_less_buoyant_as_he_swims_deeper

and now i'm curious too!

 

[H2Andy]

because ambient pressure will increase with depth, decreasing the volume (and thus your bouyancy) of any air pockets present, whether in your BC or your wet suit (within the neoprene cells) and certainly a dry suit (which acts very much like a BC)

assuming the same volume of air in your BC at 50 feet and at the surface,
at 50 feet that air will be compressed into a smaller volume, thus your bouyancy will be less than at the surface.

if you ascend from 50 feet, that air will start to expand, increasing your bouyancy (and thus possibly leading to a runaway ascent)

if you descend from 50 feet, that air will start to compress, decreasing your bouyancy (and thus possibly leading to a runaway descent)

 

[JahJahwarrior]

wetsuit becomes less bouyant--air pockets are compressed as you go deeper. Less volume of air, so less lift. Some thing with BC. Lungs too. I'm pretty sure that's what it is atleast

 

[Divmstr223]

If you've only been on one dive in your whole life...you already know the answer to this question. Do you add air to your b.c. to stay neutral as you go deeper?

There's your answer. Even without knowing all the variables, you know the answer is YES.

 

[H2Andy]

ya but the question was "why"

 

[mrjimboalaska]

but you answered the question of Why already H2.........

 

[spectrum]

Congratulations H2Andy, you apparently gave the defacto answer, it's been published at the inquiry link.

Pete

 

[Walter]

The question is based on an incorrect assumption.

The correct question is "Will a person become less buoyant as he swims deeper? Why or why not?"

The answer is "it depends."

If the person is freediving - yes. His lungs will compress and his volume will decrease while his weight remains constant.

If the person is on SCUBA and assuming no exposure suit and correct weighting, no. On SCUBA, a person's lungs will not compress. His volume will remain the same. As he uses air, the weight of his system will decrease and he and his SCUBA unit will become more (not less) buoyant.

If the person on SCUBA is wearing an exposure suit and/or is overweighted (requiring air in the BC), the suit and/or BC will compress and make the person less buoyant.

 

[Kim]

A diver won't become less buoyant. If someone makes a dive with no wetsuit or bcd (think '60s tropical diving) their buoyancy will remain effectively the same whatever depth they are.

(edit: Walter is correct....I forgot about freediving....)

 

[H2Andy]

i assumed the question's use of the word "diver" meant scubadiving, and i assumed a fully geared diver (wetsuit/drysuit and BC)

we can parse language all we want, but a diver as a package will be affected by the bouyancy of the component parts of his/her package as he descends, so the diver's bouyancy will be affected negatively. again, this assumes a wetsuit/drysuit and BC

then he will use up air, and he'll become more positive, but that comes later.

i just tried to answer the obvious question, not get into an encylopedic remonstration of diving acumen

Congratulations H2Andy, you apparently gave the defacto answer, it's been published at the inquiry link.

Pete

lol i think they just take the first answer they get