Ice diving and drysuit buoyancy

[BlackPatch]

I don't know of anyone that doesn't view ice diving as serious. A good portion of learning to ice dive is getting the proper thermal protection and the proper scuba unit set-up. There are additional areas of training necessary such as avoiding stirring up the silt, dealing with freeflows, learning communication skills diver/tender, avoiding rapid ascents, but once you get past all that and get down to your depth, a dive is a dive. The skills are the same. From what I understand a lot of those that get the card for recreational purposes never go any further with it. To do it right and by the book you need a minimum of 5 people [2 divers, 2 tenders and a safety diver.] It is very hard to get that many people together for a frigid afternoon [3-4 hours] out on the ice. Many of those that become actively involved in ice diving on a regular basis are Fire/Police search/recovery types, vehicle-through-the-ice recovery personnel, scientific divers, etc. I imagine they all get extensive further training and practice.

As to the redundancy issue I think a pony at hand is mandatory. Most of the freeflows I have experienced have involved knobs and connections being fully encased in a 1/4" layer of ice while underwater. I have been unable to shut off valves or unhook freeflowing bcds. It sounds good on paper but these fixes don't always work in the real world. A successful ice diver has learned to acquire the proper gear to minimize these issues from occurring.

As a final note - just out of curiosity - what does it cost to become a significantly-trained cave diver? I bet it's a lot. Do all new cave divers come out of training significantly-trained. I am sorry if I sound like a wise-ass but it I don't know what the training involves or what the answer is.

Old Flounder.

I use my Drysuit as a secondary inflation source.
Typically I will keep my shoulder vent open all the time so I can role slightly to vent.
My primary Buoyancy control is through my BCD. When it is time to come up, I will vent as much of the gas in my Drysuit as possible to maintain good buoyancy characteristics on ascent.
Yes, I put up with the squeeze. That's the way I do it and it works for me in Alberta fresh water lakes that are fairly Cold.

What you are describing is basically an uncontrolled ascent (am I right?) in the fact that you were being pulled to the surface. I forget the ratios that the vents can handle but I think it is 18lpm. So you didn't have a chance.

As you have already mentioned, you were not in an emergency. You didn't have clear cut comms signals defined or per planned use of those. It's a lesson more than how you dealt with the Situation.

As I see it Buddy, you did a good job, You did not have clear vis of the issue, No Effective Comms System. Get the bloke lassy to the top. THEY (not other people who were not in your shoes at THAT EXACT SECOND) can chew your ass off if they think it was uncalled for!

Bottom line. Even in Class, plan for all eventualities. But then again you know that mate, you and pretty much everyone else who has posted here, has far greater experience Diving than I.

Stay Safe and Props.

Pete.

 

[GrumpyOldGuy]

Maybe I am not getting something. Properly weighted with a single tank you need something like 5lbs of lift from your BC or D/S to compensate for the air in your full tank. Less as you deplete your gas. Big vent vs little vent on 5lbs should not matter all that much.

The tall pole in the tent is all the gas in your suite to keep you warm in 34F water and not singing soprano, for me that like another 25lbs of lift that still has to work its way out the small D/S vent. That's not changing regardless of your choice to control buoyancy with your BCD or D/S.

 

[oldflounder]

Maybe I am not getting something. Properly weighted ...........

Thank you for discussing the intention of this post. The problem is some of us do not go in properly weighted for neutral buoyancy. If our method is to use the suit for warmth then we go in a few pounds heavy so that at depth we can shoot a sufficient amount in to keep warm and make a little air bubble around the torso. At 40' this would be a significant inflation of the suit on the surface. In my case [in the past] I have used even a little more weight because I like to don the least thickness of undergarments I can get away with [so that I don't sweat to death on the surface while donning and because of the tightness/restriction of the suit that more undergarments cause.] This means a little less buoyancy characteristic with the undergarments but it also means I have to shoot in more air to keep me warm, so the added weight will hold me down. If I am at depth and I am pulled rapidly [out of my control] to the surface there is no way I can vent that air out of the suit quick enough. Whereas the same situation, using my bc for buoyancy and to deal with that added weight, gives me a better chance of dumping more of that air at a faster rate as I am ascending.


I am not saying everyone should always use their bc for buoyancy control when in a drysuit. I am just making an argument for using that method when ice diving w/tethers where there is always a chance of an extraction and rapid ascent whose rate is out of your control. Problems seem to snowball and this just seems to be an area that could cause you harm when it could be avoided with a little forethought and planning.

---------- Post added March 5th, 2013 at 06:27 AM ----------

Even in Class, plan for all eventualities.

Hi Pete - Thanks for taking the time to post - the problem here is that when you go into a class you don't know what to expect usually, so you don't know what to prepare for or how. Regarding newbies the old saying is "they don't know what they don't know." The purpose of any course should be to teach you the skills to enable you to plan ahead as you are saying. Much of proper planning is built upon experience [whether yours directly or vicariously.] A student with no prior knowledge of the subject is like a blank piece of paper waiting to be written on. They will probably make mistakes in class that they will learn from. I made a mistake in not thinking out the consequences of my actions. I had prior experience with freeflows but not with an out-of-my-control extraction. Now I do and I will likely spend a few more of those precious seconds of freeflow doing more thinking and less reacting.

 

[GrumpyOldGuy]

I am just making an argument for using that method when ice diving w/tethers where there is always a chance of an extraction and rapid ascent whose rate is out of your control.

I definitely understand if you choose to dive over weighted (for whatever reason) that the faster dump of the BCD is tempting. I also think you need to temper that thought with the knowledge that with a rapid ascent such as you encountered, you would actually need to dump gas from both the suit and the BCD simultaneously and quickly. I don't think I could do it fast enough in either case, so I really don't see a great solution.

 

[AKDiver907]

Interesting discussion - when I dive ice I generally like staying shallow because I like seeing the ice, and because in interior Alaska we usually dive ice in our local ponds and lakes and they tend to be shallow anyway (40' or less). I've seen writeups in training magazines going both ways in "cold" water applications - so when I was in instructor training for drysuit specialty I asked about BC vs drysuit for buoyancy. The PADI instruction is drysuit, and I generally agree in the short time that instructors have students in the drysuit course you want them to use their drysuit for buoyancy because they may have never done it before and need practice. Inevitably some students (recreational background) will want to avoid using their drysuit for buoyancy because they simply are not used to it. Ice divers, however, should be more experienced. Ideally, if you are properly weighted, you should have very little air in your BCD/drysuit at shallow depths. Because there is little air and therefore little pressure, neither vent very quickly. I think that I would vote to dive consistently - use the same the same technique at all depths. There is also the argument that you will always have some air in your drysuit for warmth, and having to vent both a BCD and drysuit may be problematic.

My problem with surface crew training in icediving is the SPEED recommendation for a 3 pull retrieval. I was taught that retrieval should be at a rate of 1 foot per second, like ascent rates. Catastrophic failure for both divers is rare. Divers should be able to share air if one of the divers is out. If you pull quickly - you seem to be creating a situation where you will have two victims instead of one. Both divers will experience risk of decompression illness because of rapid ascent. During a training dive, a student executed a retrieval quickly and my head slammed into an ice chunk before I could make an adjustment. As the originator of this thread commented, fast retrieval caused him to be unable to vent fast enough to overcome accelerating buoyancy and his head bounced on the ice. Even in the worst case of retrieving someone who has taken on water and drowned, doing a safe retrieval speed and preserving the health of the non injured diver seems justified. The difference in time can't be that much and the drowned victim will still have a chance at survival.

Do others agree with briefing rope tenders to always pull at a safe retrieval speed of 1 foot per second, even in response to a three pull?

 

[oneshotshooter]

I use my drysuit for more buoyancy than I thought. I was ice trained through NAUI, who treats ice diving as a technical dive. We were trained to put enough air into the suit to take the squeeze off. That was about 7-8 years and 100+ ice dives ago. We were trained solo diving. 1 diver per line. I have been "riding the bubble" for many years now. I stay a lot warmer. My longest ice dive was 93 min. Yesterday we were diving a sunken fish house under the ice. When I loaded my backplate/wings into the truck, some water poured out. I then realized my dump valve had come undone! I completed 2 dives without knowing!:doh:
The sunken fish house now has been occupied by a zombie horde. We placed signs underwater around the perimeter to warn future divers. It was a beautiful day on the ice!

The boss 9' v plow makes shoveling rays a lot easier!

 

[rongoodman]

There's no way I would be under the ice, as in any other overhead environment, without doubles for redundancy, whether sidemount or backmount. Even with Al80s, that's nearly 12 lb of gas, which would mean having quite a bit of air moving around in a dry suit. to support it. Seems like the potential for a real problem, so I wouldn't do it.

 

[oneshotshooter]

There's no way I would be under the ice, as in any other overhead environment, without doubles for redundancy, whether sidemount or backmount. Even with Al80s, that's nearly 12 lb of gas, which would mean having quite a bit of air moving around in a dry suit. to support it. Seems like the potential for a real problem, so I wouldn't do it.

I dive a hp 100 with a alum 40 for redundancy. We dive tethered to the exit with a 150' safety line with a tender and are never more than 150' away from the hole. We also have a safety diver. I dive doubles on deep dives but they are not practical for local ice diving. Average depth on most lakes around here doesn't exceed 30-40'. Have you ever been ice diving?

 

[rongoodman]

No, almost all my overheads have been in caves. The point I was making, though, is that that's more gas than I would be willing to support with just the bubble in my dry suit. (And if I ever do try it, I will be in doubles, either side or back mount!) I'm not sure where I come down on the tethered vs. non-tethered(standard cave procedure) divide yet.

 

[oldflounder]

theres' no way i would be under the ice, as in any other overhead environment, without doubles for redundancy, whether sidemount or backmount....

I am not sure that the doubles is the solution that quarantees a more safe ice dive. Personally I think having 2 circuits totally independent of each other is more important to this discussion. I don't use an octo ice diving on purpose [it's a freeflow issue I'll discuss later].

I have 1 circuit [pony 13 hose clamped to primary tank upside down, button gauge, single long 6' hose hooked into my Air2 and bc]; the second circuit goes to my spg, drysuit and second stage bungied to my neck with snorkle keeper for quick release. I sling a 19 on right side with reg on short hose and secured to bc with cave line [avoiding metal-to-metal connections as much as possible] . I carry a large pink knife on my left shoulder strap. In case of OOA you take my primary out of my mouth, yank it off the keeper and get composed. Then you take my knife off my shoulder cut through the strings and toss the knife away if you are panicky [your life is worth more than the knife, which, being pink I can probably find later anyway...I will only ice dive 35 - 40' max. You probably can't unhook the mounting clips with big gloves on].

The reason that having everything on one circuit is bad is that (1)in case of a full blown freeflow your 1st stage freezes opening both your second stages. They act as overpressure relief valves in this case. Air is escaping everywhere. (2)Also your bc inflator may freeze open and you can save gas loss by unplugging it if you do it before it ices up. (3)Another situation I had was when I went in and my drysuit inflator was frozen shut somehow and I couldn't put any air in my suit.

---------- Post added March 25th, 2013 at 11:20 AM ----------

... We were trained solo diving. 1 diver per line... My longest ice dive was 93 min... The sunken fish house now has been occupied by a zombie horde...

How do you keep them inside the fish house.......I imagine you fight them off with spearguns.... How do you carry all the extra spears???

I'm going to comment on your 93 minute dive in the reply to the next quote.

---------- Post added March 25th, 2013 at 11:59 AM ----------

My problem with surface crew training in icediving is the SPEED recommendation for a 3 pull retrieval. I was taught that retrieval should be at a rate of 1 foot per second, like ascent rates. Catastrophic failure for both divers is rare. Divers should be able to share air if one of the divers is out. If you pull quickly - you seem to be creating a situation where you will have two victims instead of one. Both divers will experience risk of decompression illness because of rapid ascent. During a training dive, a student executed a retrieval quickly and my head slammed into an ice chunk before I could make an adjustment. As the originator of this thread commented, fast retrieval caused him to be unable to vent fast enough to overcome accelerating buoyancy and his head bounced on the ice. Even in the worst case of retrieving someone who has taken on water and drowned, doing a safe retrieval speed and preserving the health of the non injured diver seems justified. The difference in time can't be that much and the drowned victim will still have a chance at survival.

Do others agree with briefing rope tenders to always pull at a safe retrieval speed of 1 foot per second, even in response to a three pull?

I think there should be more communication with the tender especially in a training situation. I think there should be a signal that says "I am having issues here and I need to get back to the hole asap with your assistance. This is not an emergency yet." There should be another signal for "We are having an emergency situation, get us the Hell out of here inmmediately; damn the torpedoes-full steam ahead."

You can't really plan to share air under the ice in a normal situation with the standard gas management plan. A couple months ago I had a free flow on the surface with a steel 72 upon entry. The 1st stage blew and then both secondaries opened up as pressure relief. I was empty in 90 seconds and no way to stop it as the shut off valve was frozen open and encased in ice.

This is 90 seconds on the surface with a full tank. Consider halfway into your dive at 40'. How long is that air going to last. Consider as in one of the previous posts that you are 90 minutes into your dive. You had better not be far from the hole and had better not have a buddy wanting to share your air.

Just take a scenario where you and your buddy are 100' from the hole, both have on steel 100's without ponies, 35' depth and 2000 psi left. Your buddy, the gas hog, wasn't paying attention to his gauge and is at 300. Because he is so low you head back to the hole and start sharing air. You get 50 feet and you're both taking turns sucking nervously now. A freeflow starts and everything opens up. Realistically you might have 20 seconds of air to get 50' more to the hole.

If they think they might not make it in time and give you 3 pulls and you pull at 1 foot per second [they are 50' away] I hope they are good at breath holding in a panic situation. Another thing about the 1' per second rule: I can swim faster than that and I am going to be trailing a lenght of cord/rope behind me that could be an entanglement issue for my buddie(s).

I swear by a pony during ice diving!!!

The original reason for my post has become a mute issue. A couple weeks ago I tore out my drysuit zipper for the second time and this time I can't fix it myself. I am back to diving wet for the rest of the ice season!!! A fast ascent could still be an issue but now I haven't got to worry about 2 vents.