Drysuit diving without enough weight. Dangerous !!

[wolf eel]

[I rented a drysuit on the weekend and my LDS estimated my weight requirements to be approximately 32 lbs. I hadn't dove dry in a while and had no idea what my weight should be. When I got in the water I discovered there was no way for me to submerge with this much weight, even with all the air out of my BC and suit.]

How Tall are you ? If you are greater then 6'9 then I get it. Did the suit fit you ? I dive dry almost every day and my weight is about the same and I use 32lb's of weight with a tri lam. I use up my tanks all the time and never have raised from the bottom ( good title for a movie)
SO I am confused how you did and why you had to add so many rocks.!!

[I had a problem with my Octopus that started freeflowing when I reached 50 feet or so.. This resulted in most of my air being expended from my tank very fast, making me positively buoyant and resulting in an uncontrolled ascent to the surface. At the time I thought it was a problem with my suit not venting fast enough, but on later reflection realized it was a problem with weight. Obviously I didn't check my weights correctly and took a huge risk diving with rocks in my pockets and full tanks.]

So I guess you started on your way to the surface ? :thinkingo

[I wonder what the weight differential is between a full tank and an empty one and how much extra weight is required to compensate?]

In the time you where in the water you unless you are a air hog should have had at least 2200 lb's so when you had your error you would still have been free flowing at the surface with air in the system.

[My LDS has offered a free rental as a result of their weight estimation error. They are guessing now I should have gone out with 40 lbs instead of 32]

Thats nice of them.

But I would look at not useing your BCD as it still had air in it. Try your best not to use your BCD as it will effect how you have accents and decents. I would guess you had a little air left in it and that may have helped you not decent. The arm pit valve is because you had your sleeve rolled a bit as that is not a place that a valve is placed. To dump air reqiuers shifting air in the suit to the valve. All dry suits work the same lack of dry suit time helped you alot.

Cheers :sunny
Derek

 

[scubapolly]

I dive dry with no ditch-able weight. I would much rather carry useful gear than a bunch of useless lead. DUI Tri-lam suit. DUI polartech undies, over thinsulate long-johns. Double steel 85s. and a stainless back plate. If I am carrying more gear (reels, lights, deco bottles, etc) I switch to aluminum tanks (otherwise I am way over weighted). I just purchased a Transpack, so that I can drop the weight of the plate when needed.
I actually had a conversation with several knowledgeable divers about the issue of ditch-able weight. All were in agreement that the hazards of ditch-able weight far exceed any safety benefit they might provide. I have heard a lot more stories both on this board and in person about weight pockets slipping out, or a weightbelt coming off. As you should learn in your OW class a buoyant assent is your last option, and should only be performed when you fear that you will become unconscious before reaching the surface.
To add to this, if you are diving with the 40 lbs on your weight belt that you are saying that you need, ditching this weight would result in an unbelievable amount of positive buoyancy (initially 40 lbs, which would quickly increase as any air in your drysuit or BC expands during this assent) which would turn you into a human rocket. Reconfiguring you gear so that you only have a few pounds (10 or less) is much safer.

To answer your question on the weight shift of tanks during a dive, the easiest way to think about this is that air weighs 0.08 lbs per cubic foot. Therefore an 80 would have 6.4 pounds of air in it, 121 has about 9.6 lbs.

Out of curiosity what kind of reg is your octo that free flowed? You mentioned that you hadn't dove a dry suit in a while. Where you diving gear that is capable of handling cold water? I have seen a lot of people get themselves into free-flow issues diving our local quarries and the great lakes with gear that they purchased with the intention of only using in the Caribbean

Glad to hear you made it out of this one unscathed, hope this helps avoid future situations.

Polly

 

[diverbrian]

More commentary. I dive dry quite a bit as well. As I get cold easily I wear two sets of undies under my Andy's DS-1. I wear a set of Bare fleece undies under my Andy's "bunny suit".

With doubles, I drop like a rock and little will change that. With a single 120, I am using 12 pounds. I weigh about 185 pounds (put on some weight this last year).

Forty pounds of ditchable sounds high to me, but without physically seeing your thermal protection (which has thrown me off in a similar manner in the past) it is hard to tell. I typically dive with my drysuit exhaust full open so that I all have to do is raise my arm and the suit vents. Also, I do not use the drysuit for buoyancy although using it for comfort at depth means that I rarely have to touch my BC at depth. Let's face it, a little squeeze isn't that bad. But having the drysuit trying to "kill" me isn't what I would call fun and it gets cold too.

Personally, I think that the analysis probably should have started when you went to using the rocks before you sank. Also if neither you nor the LDS had a good guess as to the weight that you require, a pool session or shallow shore dive would have been in order to find out. The refresher would have been a good thing, too .

As it is, you came out in one piece and didn't do anything that many other drysuit divers haven't done once upon a time.

PS I recommend get that octo upgraded to a full service reg. if you haven't done so. Free flowing secondary regs aren't fun either even though they are not the end of the world.

 

[Brian Gilpin]

I weigh about 170 lbs. and was using an aluminum 80 tank. I was using a bilam shell suit.

The big difference affecting the buoyancy (I think) was that I was wearing 36 oz fleece under it (Whites Pro undies) and this added alot of bouyancy.

I think you may have other problems. Forty lbs is bordering on oppressive. I weigh 225 and only need 22 including my BP light cannister etc with a DUI 50-50 which shoul have similar properties to your rental suit. I wear Polartecs but I cant imagine this making an 18 lb difference.

Spend some time at the pool with this suit to get comfortable and try to figure out whats goin on.

 

[Rick Inman]

40lbs sounds an incredible amount of weight.

Time and again I see dry suit divers over weighted - I know I was, and had several similar posts to yours. I would have sworn that I was dumping all my air and still couldn't get down. When in fact, it takes several dives and lots of practice to really get all the extra air out of your BC & DS. You really gotta' do the funky-chicken squeeze, turn your body and really get all the air out. Then you won't need those pesky ankle weights 'cause you won't have all that extra air shifting around in your suit.
So, good news! Lots of diving will solve your problems!

 

[tel-scuba]

40 pounds? Are you sure? I'm about your size, and frequently dive with what sounds like your configuration. When I dive dry with thick undergarments, using a single aluminum 80, 24# is quite sufficient. As other posters suggest, make sure you've purged all the air from your suit prior to the dive. Also, dive, dive, dive! Practice improves your breathing and buoyancy, and magically, your weight requirements drop dramatically! Good luck!

 

[divenut2001]

I rented a drysuit on the weekend and my LDS estimated my weight requirements to be approximately 32 lbs. I hadn't dove dry in a while and had no idea what my weight should be. When I got in the water I discovered there was no way for me to submerge with this much weight, even with all the air out of my BC and suit.

My buddy managed to jam enough rocks into my BC pocket (at my suggestion) to get me under.. just barely. Once submerged it didn't seem to be a problem at all since i became negative as depth increased. The one thing we didn't consider was the effect of weight change as air was used from the tank.

I realize this was pretty stupid now..

At the same time, I had a problem with my Octopus that started freeflowing when I reached 50 feet or so.. This resulted in most of my air being expended from my tank very fast, making me positively buoyant and resulting in an uncontrolled ascent to the surface. At the time I thought it was a problem with my suit not venting fast enough, but on later reflection realized it was a problem with weight. Obviously I didn't check my weights correctly and took a huge risk diving with rocks in my pockets and full tanks.

I pulled my suit collar open halfway up the ascent to the surface to reduce the speed considerably, but I didn't have enough weight to remain under the water once my tank air reached a critical level. I had no problems as a result of the uncontrolled ascent luckily. We were in the water about 25 mins.

I did learn a valuable lesson though, so thought I would pass it on here for everyone to read.

When setting up weight for use with a drysuit, be sure to estimate using an empty tank, not a full one, and if your light on weight, don't just add enough to make you negative with a full tank, you need a few extra pounds to compensate.

I wonder what the weight differential is between a full tank and an empty one and how much extra weight is required to compensate?

Lesson learned.

My LDS has offered a free rental as a result of their weight estimation error. They are guessing now I should have gone out with 40 lbs instead of 32.

When you go for the free rental try it on at the shop first so you and they both know that it fits and that you're wearing it right. Not knowing the exhaust valve shouldn't be in the arm pit tells me you need further training.

"PLEASE" check it out in a pool first. Take "plenty" of extra weights with you to the pool and the dive site so you can add or subtract weights evenly.

The only time I've heard of people using rocks for weights was in an (emergency) attempt to prevent a run away ascent, "NOT" so they could make a dive.

You should probably take a dry suit course or at the very least read the manual, (again if it's been awhile).

Glad things worked out ok. Happy diving...

 

[wolf eel]

[ Also, I do not use the drysuit for buoyancy although using it for comfort at depth means that I rarely have to touch my BC at depth. Let's face it, a little squeeze isn't that bad. But having the drysuit trying to "kill" me isn't what I would call fun and it gets cold too.]

Why is your dry suit going to kill you ? :icon10: When I am working in shallow I only use my drysuit I do not even have a BCD on.

I just feel that if you have to compensate for two sources of air it just makes for error. I think anyhow.

Do they not teach you not to use your BCD with a drysuit at depth ? somehow I thought it was taught that way. Only to use your BCD at the surface.

Cheers :sunny
Derek

 

[divenut2001]

Why is your dry suit going to kill you ? :icon10: When I am working in shallow I only use my drysuit I do not even have a BCD on.

I just feel that if you have to compensate for two sources of air it just makes for error. I think anyhow.

Do they not teach you not to use your BCD with a drysuit at depth ? somehow I thought it was taught that way. Only to use your BCD at the surface.

Cheers :sunny
Derek

Big discussion on that topic on the DIR forum if anybody's interested: http://www.scubaboard.com/t71611-bcd-vs-dry-suit-for-buoyancy.html

It makes sense to me and is the method most used by divers I talked to when I first got my dry suit.

I tried using the dry suit at first like Padi teaches but found it much easier using my BC for buoyancy with just enough air in the suit to take the squeeze off.

But, there are those like you Derek that only use the suit for buoyancy and swear by it.

 

[AEIOU]

Big discussion on that topic on the DIR forum if anybody's interested: http://www.scubaboard.com/t71611-bcd-vs-dry-suit-for-buoyancy.html

It makes sense to me and is the method most used by divers I talked to when I first got my dry suit.

I tried using the dry suit at first like Padi teaches but found it much easier using my BC for buoyancy with just enough air in the suit to take the squeeze off.

There are those like you Derek that only use the suit for buoyancy and swear by it.

Good link above. I was also taught that a bc is for buoyancy and a dry suit is for keeping you warm and dry. I put just enough air in mine to keep from being squeezed.