Quote: (Originally Posted by
GLOC)
I and several others (total 5) are off to Scapa this year for at least 4 mix dives (the remaining 6 being Nitrox) and we have a couple of options with regards to gas availability. Gas planned for use is 18/45 with 50% deco.
Regards
We do this ALL the time. First you need to get out of the "perfect mix mode" and put on your "creative mixing in the field cap"
Take 2 twinsets. .... fill them with 14/60 trimix full then follow rule of thirds plus a little (always more is better) then top with air to approx 150 bar (do the math on your own) you will end up with about 18/35.
Another thing we do is to start one set at 18/45 and the other set is 10/90 we use the 10/90 set as a "sweetener" to set 1 after dive 1 and then top with air (if you have compressor on board) and keep doing this till you are done ---
On the deco gas bring deco bottles in 50% and 100% do high helium mix dives with Both deco gases, then top the 50% bottles till you end up with 36% EAN and the 100% bottles you can still use until you reach approx 100 bar then top those to make 50% -- critical to relable on the spot so the cylinders do NOT get confused.
As to the rest of your twinsets for nitrox two big bottles of oxygen will make many many twinsets of Nitrox 32%
I have traveled with boosters and compressors and all kinds of kit to make all this work and usually we have 10 divers most of which are so hellbent on having a perfect mix we have just made it so that if you want a perfect mix YOU bring all the sets of gas YOU want to have. Otherwise just learn to be a bit creative and a little accomodating and you can have a lot of fun and still do perfect dives. It sure makes it a better evening if you just have to top up some sets with air than to have to dick around (states term) for 5 hours filling and tweaking gas.
The key here is to work out your gas plan FIRST and let everyone know what that gas plan is. If they break the gas fill plan by breathing down too much or not starting out with the right start mix then they get stuck with what they get.
I had a few folks on a project this past year that broke the gas fill plan and it ended up costing them a bit for all the extra helium we had to use to get them topped.
Welcome to getting gas in the field!
Cheers