Cause of high consumption rate

[danvolker]

You seem to have some deep-rooted issues with drysuits that no DS diver I know shares with you, and I know quite a few recreational DS divers. I used to know a couple of semidry-users, but they also dive dry now.

You are of course entitled to your own opinion, so I won't try to discuss the issue any more with you. However since you're not entitled to your own facts, I want to point that you're widely exaggerating the challenges of using a DS.

I think you are misinterpreting. I think you are exaggerating the skill level/abilities of most recreational divers---which I am considering typically very poor....the agencies see this as "average". I see it as not being taught enough, to even know what you don't know


In any event, the OP was asking about ways to potentially improve SAC rate...which I have tried to do. Maybe you would like to take a shot at this , rather than being so incredibly defensive about your own gear ?

 

[DivemasterDennis]

Here is a checklist to run through as to possible factors causing unusually high air consumption rate, starting with what has been discussed: gear used. Also consider: personal physiology ( congestion? lung capacity), movement or activity on the dive; depth; stress factors on dive including lack of familiarity with location, first time in these kinds of conditions,unusual or aggressive animals present, limited visibiity, choppy surface conditions, etc. Chances are there were some non-typical stress factors present,and the dry suit in warm water may well have been one of those. Keep good logs of every dive and common factors are likely to emerge.
DivemasterDennis

 

[waterpirate]

I am a recreational diver and my sac rate is awesome when I dive dry!

 

[TSandM]

Another thing that occurred to me this morning is that drag is proportional to the square of the velocity . . . if you are one of those people who likes to move very fast through the water, the change from a streamlined wetsuit to a relatively "corrugated" dry suit will be more noticeable than it would be for those of us who, as Mark Messersmith describes it, "float fast".

 

[WhiteSands]

WhiteSands, check your trim -- if you are out of trim in the dry suit and having to dive negative because you're feet low (or positive because you're feet up) that will waste a lot of gas. If you are having a lot of buoyancy variations, requiring filling the suit and dumping it, that will impact your gas usage, too.

Hi Lynne,
My buddy shot some pics and videos of me in the drysuit, trim seems to be ok.

I try as far as possible to inflate my BCD orally, to save gas. AFAIK, adjustments to drysuit air is only done when changing depth and feeling "crushed" and on ascent.

---------- Post added December 23rd, 2013 at 02:11 PM ----------

Another thing that occurred to me this morning is that drag is proportional to the square of the velocity . . . if you are one of those people who likes to move very fast through the water, the change from a streamlined wetsuit to a relatively "corrugated" dry suit will be more noticeable than it would be for those of us who, as Mark Messersmith describes it, "float fast".

I was actually using modified frog most of the dives unless there were currents, then I'll switch to full frog or modified flutter...

 

[Agility]

Hi Lynne,
I try as far as possible to inflate my BCD orally, to save gas.

I tried this too and it did not work out for me, as I recognized I was taking a deeper breath to inflate my BCD so I returned to using the inflator but press it only a tiny little bit to let as little air in as necessary breathng comfortably all through the action.

 

[Storker]

AFAIK, adjustments to drysuit air is only done when changing depth and feeling "crushed" and on ascent.

If you're diving in cold water (single digit C, sub-50 F), remember that it's not the undergarments that provide the insulation, it's the air; the undergarments are there only to trap the air and keep it in place. So if you start feeling cold, try to add some more air to your drysuit than is needed to just avoid squeeze. You might need some more weight, though; I routinely use about 2kg more when it's cold, for comfort and insulation.

When I started my (drysuit) diving, I was using the suit for buoyancy, per PADI's instructions. After becoming more experienced, managing two bubbles wasn't that difficult any more, so I started using my BCD for primary buoyancy control underwater. However, when the water gets winter diving cold (sub-5 C, sub-40 F), I'm back to adding (most of) the air to my DS, since I found out that I got colder when I was using my BCD for buoyancy and added just enough air to the suit to avoid squeeze. I still empty my suit for air during my safety stop, though, since it's a lot faster to vent air from the BCD, and I still have to be careful to avoid fast-ish ascents during the last few meters to the surface.

 

[ajduplessis]

Which specific skills would you say drysuits are bad for?

Removing your BCD/BP-W during entanglement. It's not good when you quickly need to stop someone from rocketing to the surface as the suit does not dump fast enough, it is not good for basic performance skills in strong"ish" current due to drag factor, it adds to task-loading during OOA and recoveries, becomes potential failure point (flooding/ malfunctioning valves or LPI).

 

[RJP]

Yep, in agreement with all of the comments about ditching your dry suit in favour of rash vest and boardies. It will undoubtedly help with air consumption compared to dry suit and more weights. Plus it helps you abide by the number one rule in diving....always look cool!

And swim fast as you can...

 

[Edward3c]

Hi WhiteSands,


You haven't said which type of dry-suit your using membrane or neoprene?