tethered or not?

[rookers]

I will start by saying I will only teach tethered, but have dove both styles here in Colorado. I am more comfortable tethered when the visibility is terrible, as is the case with many of the sites here. With a competent team, in decent conditions, I'd run a reel.

 

[Cave Diver]

Interestingly enough, tomorrow is the 4th anniversary of our accident on 18-02-07. The report was pretty detailed although it was not discussed in length on SB, but on Ontariodiving.com and TDS it was. If someone can find it, feel free to post it in here, I dont mind discussing it with open minded divers looking to learn from it. Im not interested in being lectured by south florida ice diving experts however, no offence.

Thanks for that offer Kevin. I located the post you made and I'm going to copy it to a separate thread for discussion.

http://www.scubaboard.com/forums/t2...74-repost-permission-ice-diving-accident.html

 

[Jim Lapenta]

Thanks John. I have a few observations and a couple questions that I will post later on the other thread. And thanks to Kevin for being willing to discuss this. Some valuable lessons I think will come from it.

 

[jjones9527]

Some valuable lessons I think will come from it.

It totally changed what is acceptable risk for us, and made us take a serious look at what were were doing and how we were doing it.

 

[Cave Diver]

yup, once did a untethered dive running a reel...from the shore. Came back to find the ice had blown back in. So there we were , two experienced ice instructors who knew better. we swam along the edge of the lake until clear water. luck smiled...

in a river with current...that is a dang hard one to make the untethered argument.

How big a concern is closure of an ice hole for untethered divers. Obviously if it closes, it's a problem, what I mean is how significant are the odds of that happening. Moving water seems more likely. Smaller lakes, maybe not so much?

If untethered, do you leave a "bubble watcher" on the surface, or just take your chances?

 

[cerich]

How big a concern is closure of an ice hole for untethered divers. Obviously if it closes, it's a problem, what I mean is how significant are the odds of that happening. Moving water seems more likely. Smaller lakes, maybe not so much?

If untethered, do you leave a "bubble watcher" on the surface, or just take your chances?

In EXTREME cold the hole could freeze up over you, thus the tender at the surface. If the cut ice from the hole manages to get back in the hole (unlikely), you could handle from below, however it you didn't have a line to follow to the cut out...it could be VERY hard to find.

A bubble watcher is not gonna see any..the ice.

 

[Cave Diver]

A bubble watcher is not gonna see any..the ice.

Yes, I realized. I was using it as a more generic term to refer to someone who stayed near the entrance to ensure ice didn't drift/accumulate or what have you. Didn't know if that was commonplace for an untethered team or not.

What's an approximate threshold for defining "extreme cold?"

 

[cerich]

Yes, I realized. I was using it as a more generic term to refer to someone who stayed near the entrance to ensure ice didn't drift/accumulate or what have you. Didn't know if that was commonplace for an untethered team or not.

What's an approximate threshold for defining "extreme cold?"

depends on the person and their tolerance. Most recreational ice diving is done with say 5 degrees each way or so of the freezing point for air temp. I personally would consider extreme cold as -10 c or colder. I have done ice diving in colder and yes, ice reforming in the hole can be an issue. I personally would NEVER dive ice without surface support.

 

[Jim Lapenta]

For me it is anything under say 20 degrees. above that with no wind and sunshine is downright balmy! The water will rarely get below say 36 -38 in a lake or quarry. Once the ice forms it does hold some "heat" in. Moving water is a different story. Some of the guys at the quarry two weeks ago went on a bottle dive before that in the river and were reading 32-34.

Another concern along with the water freezing is lack of light. One of the reasons we shovel a circle the length of the tether and run lines in the snow radiating from the hole. Not only do they allow light down but they also point they way back to the hole should the diver lose the tether. If you go to my website/photos/ice diving and look at the last photo in the series you'll see what I mean.

I have until now done only tethered dives in non current conditions and see no IMMEDIATE change coming. At some time would I do untethered? Probably but I would follow wreck protocol for me and run a line from a reel to the hole. Even in a quarry or lake. A snowstorm coming up could "erase" the lines running to the hole, get turned around and mistake an air bubble for a hole which would be possible if it settled in an old cut out, or have some type of silt event in a shallow quarry and the results without a line of some kind could be very bad. There is also the idea that having a surface team is damn near necessary for getting out of the water in a drysuit with tanks and any other gear. Often there is no ladder.