Quote:
| Originally Posted by Mr_Brown I have been practicing shutdowns recently at the NDAC. Mostly doing them at 10-15m, after a 40 min dive in about 8 degrees, when your hands are starting to feel the cold, am now looking to increase the depth.
Is this advised when looking to do the TDI advanced Trimix... (what depth do they have you, do your shutdowns and within what timescales. 30 sec's 1 min? )
I suppose you should be compedent at doing them at any stage during the dive but just want to know what YOU all think. |
Realistically you need to be shutting down or isolating in under five seconds.
Personally I went for isolation first and I only had the central isolator open two turns. I used a slob knob as manual shut downs were too slow. On average id have the isolator closed in close to two seconds.
Some schools of thought have the isolator fully open but they also tend to go for the primary reg post first rather than the isolator. Which is cool assuming the fault is on the primary reg and you can reach it OK.
I could reach back with my left hand better than my right, so I ran my main reg off the left post. Id isolate with two turns on the slob knob (using my right hand) then at the same time id reach back with my left to isolate the primary reg.
I have always found this very hard to do. So having isolated meant I at least saved half my gas. Primary reg shut downs some times didn't happen at all or took 10-20 seconds which is way too long.
Time how long it takes you to get to and shut down the primary reg. Then hit the purge button on your reg for the same period of time so as to see how much gas it would have cost you. Once you have that number you can plan your gas strategy accordingly.
ATB
Mark