Suit compression

[bill-da-ho]

recently I posted that me and my fiance' made it to the wreck that we had tried to get to befor, when we got to the deeper wreck, " the John Webber" it was at about 45 feet, when I got to about 35 there was a thermocline, and I felt like I started to slip deeper, I wouldnt call it panic, but it did concern me for a second till I realized I had to add a bit of air to the BC. Once we got out I figured that it must have been to the suit compression, or is there another reason for this? The cold water? going thru the thermocline? And so this was the first time I experienced this feeling,do you get use to that with experience? Does the adding air become automatic? just curious, thanks

 

[NadMat]

yes, compression in the suit and to any air in bc. after a while adding air descending and releasing it on ascent will become pretty automatic.

 

[ApexLongimanus]

remember that air volume is getting compressed the deeper you go. thus, lift is being reduced. as a result you have to add air to your bc on descent and vent air on ascent (air volume expands) to maintain neutral buoyancy. compression of your wetsuit and change in water temp also play a role but a minor one compared to above.

 

[robint]

yes, yes, and yes. Also, age of suit is a big factor in compression as bubbles get permanently compressed over time and don't offer the same thermal protection. (another reason I tell people to get a good quality suit, they last longer)


it all gets easier the more you dive!

 

[don Francisco]

On the surface a neoprene wetsuit is basically a sponge, wherein air cells provide bouyancy and insulation. As you descend, the increasing pressure shrinks these air cells causing the suit to lose both bouyancy and insulation.

Eventually the air cells are sqeeezed to almost nothing and you're no longer wearing neoprene foam but essentially solid neoprene, which has negative bouyancy and is useless as insulation. This is usually perfectly matched to when you pass through thermoclines in accordance with Murphy's Law.

Yes, adding air to your BC compensate for the loss of wetsuit bouyancy will become second nature along with the process of fine-tuning neutral bouyancy.

BTW- don't forget the process reverses, so that you'll have to vent air from the BC as you ascend and the wetsuit becomes bouyant again.