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Steve Schinke <tekdive@ho*.co*> writes:
> This person was in support of some of the large diving factions
> standards involving a five person team requiring the divers to be
> teathered and a teathered safety diver plus two line tenders.
That style would be drawn from commercial diving protocols; that would
likely have been the readiest source when NAUI and friends were figuring
out how to ice dive and live.
> my argument was that this seemed to be a little over excessive. I
> argued that Ice should be dove like any other overhead environment
> using reels, and gas management principles, and that teathering
> unnesessary. The divers should be competant enough with there skills
> that being roped together and to the surface is ridiculous.
A lot of recreational divers only have a single (they look up at the
high-tech guys with pony bottles, if you can believe that) so the whole
idea of shutting off a valve when a reg freeflows is foreign to them.
They need to get back out before it can drain their tank, and having a
rope and a surface tender makes that possible. The recreational ice
diving protocol is deliberately as simple and foolproof as possible.
> usually the way my buddy and i dive is with reels and ice screws in a
> two man team using thirds.
A few points that apply even to those of us with doubles and two regs and
caving skills and equipment are that:
(a) wearing heavy three-finger gloves makes you clumsier, so it's
harder to handle a reel and lightweight line, or to turn valves [note
that Florida cave protocols assume no gloves]
(b) if one reg freeflows under such cold conditions the other may not
be far behind
(c) during the first five minutes of the dive, when your face hasn't
gone numb yet and you're going AAAAUUUUGHHHH, it's nice to not have
to think about possibly having to do any survival skills more complex
than pulling on a rope three times.
Because of those factors I don't think you can directly transfer cave
skills as if you were in Florida. I think the best technical-icedive
configuration lies somewhere between there and the full five-diver
tethered setup. I don't claim to have all the answers, and I'm keeping
an open mind.
My best ice dive last season was after my buddy had to scrub due to a
predive freeflow; I was down solo, tethered. This I think comes a bit
closer to the original tethered commercial diver model, without a
second diver in the water to get ropes crossed. It worked really well,
and this can be done with two divers and a tender.
With two divers each independently tethered to anchor points on the
surface, I can't see the real benefit of the safety diver, unless perhaps
less-experienced divers are going in the water and you want to be able to
put in somebody competent to help them. Still, I'm not going to change
the rules I was taught on my ice course until I'm certain I and my buddies
have a better system and we've gone through the contingencies and we're
sure it'll work.
Note that it's generally only possible to get one dive per regulator;
postdive on a below-freezing day, a wet regulator will freeze up and
freeflow on any attempt at a second dive. If one diver is going in first
and then sitting safety for the other(s), having a dry spare regulator
would be useful. I'd never previously had that luxury, but having stage
bottles in summer means having extra regs in winter. The backup
regulator (left-post, if Hogarthian) should be okay, having a chance to
rise to the temperature of the water before being needed.
Because of ice-up and freeflow issues (note also the LP inflator freeflow
discussion today) and the extreme cold, it probably goes without saying
that one stays in the no-decompression zone under the ice.
Make sure your tether ropes are long enough; 50' ropes in 30' of water
when people miscalculate the wreck site by 40' adds up to the classic
3-4-5 triangle and means you can just barely reach out and touch the
nearest part.
--
Anthony DeBoer <adb@on*.ca*>
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