Over the past 40 years, I've logged about 300 - 400 dives on the Arabia, I'd guess. Way back when, I had a few free-flows on her, and I still see lots of them...
-
(For those that aren't familiar with Tobermory, it's often said that it's the place where cold water was invented... Even in the height of summer, the water temp below 70' tends to hover in the 39F - 41F mark, and I have been on dives even in August where the temperature was only 34F...)
Anyway, this is what I can offer as advice...
1) Have the IP of your reg tuned down a couple of notches. Perry @ G+S in Tobermory is the best guy I know for a quick tweak... If you don't have a cold-water specific reg., get one.
2) Carry a redundant air supply... a pony bottle, isolated doubles, sidemount... Some system where you can shut down the free-flowing reg for a few minutes while it thaws out.
3) Over the years, there has been at least two DOUBLE fatalities on that wreck that were the direct result of freeze-ups leading to botched air sharing. If you like your buddy, equip yourself (and he should too) to dive independently, and learn how to deal with your problems yourself.
For what it's worth, I think you dealt with your situation appropriately, given the gear you had on, and your profile. Even if you were close to or over your NDL, your solution was still appropriate. With a chamber in town, a bend is generally easily "straightened". To quote Dr. Harpur, "We can fix "bent". We can't fix "dead""...
But if you intend to dive these somewhat deeper dives, then get yourself properly equipped.
And be happy it wasn't your BC inflator that froze up (too). Now that's an adventure!
---------- Post added April 25th, 2014 at 07:24 PM ----------
I dive double LP72s primarily so I would just shut down that post, check my gas pressure to see how much I lost, and signal that I have a problem. If I have a lot of gas left, I may try to de-ice the frozen 2nd stage by flooding it with the warmer ambient water for a minute.
I think it's important to note that the primary reason that a reg free-flows (assuming it's properly de-tuned etc.) is the breathing gas isn't as dry as it should be. As a result, when one reg free-flows, there's a reasonable chance that the second one will as well, once it's put to work. (as well as suit and wing inflators)
At this time of year, I tend to dive with my isolator closed, and I alternate regs every few minutes, much like I would if diving SM. As mentioned, the surrounding water is above freezing... it's the breathing that causes the extra cooling, which can lead to freeze-up. Giving your regs a "breather" works wonders.
As for the comment above about the surface not being an option... that might be the case in many situations, but the OP referred to a profile where simply surfacing was a completely viable (and sensible) option.
Incidentally, these pictures were taken yesterday by a friend of mine at the Lighthouse... Global Warming my arse...