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nic_the_greek · January 15th, 2007, 02:42 PM

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.

1. Pay for He on the boat at 3p per litre (O2 is 1p per litre)
2. Take enough twinsets with gas in them (we are taking a Transit but that could be converted into a LWB transit!)
3. Take J's/get J's delivered and cascade
4. Take J's/get J's delivered and boost

If we fill our own tins with He, the skipper doesn't want it done on the boat but the quayside, O2/air tops will be carried out by him.

So, here comes the difficult questions. Once I have worked out the litreage (sp?) of gas required, how do I work out how many J's I need to order if we are going to cascade?

There is already one blender on the team but by the time we get there, there should be 3 of us.

Finally, how much difference does it make if you use a booster (Haskell?) and does anyone know where we can hire one?

Regards

Firstly, this sort of calculation should be covered in your Blender training - both the TDI and PSAI exams had questions regarding gas planning for expeditions. Speak to your instructor, I'm sure they will help you go through it.

Secondly, last year we took a twinset of 30/70. By decanting 75bar in to an e,pty twinset and topping with air to 210bar you'd get a 24/25 mix. Not exactly what you're after but it was good for us and is divable to 45m.

Cheers/Nic

January 15th, 2007, 02:42 PM	#2 (permalink)
nic_the_greek(Offline) New Member Join Date: Jan 2006 Location: Gosport, Hants Posts: 87	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. 1. Pay for He on the boat at 3p per litre (O2 is 1p per litre) 2. Take enough twinsets with gas in them (we are taking a Transit but that could be converted into a LWB transit!) 3. Take J's/get J's delivered and cascade 4. Take J's/get J's delivered and boost If we fill our own tins with He, the skipper doesn't want it done on the boat but the quayside, O2/air tops will be carried out by him. So, here comes the difficult questions. Once I have worked out the litreage (sp?) of gas required, how do I work out how many J's I need to order if we are going to cascade? There is already one blender on the team but by the time we get there, there should be 3 of us. Finally, how much difference does it make if you use a booster (Haskell?) and does anyone know where we can hire one? Regards Firstly, this sort of calculation should be covered in your Blender training - both the TDI and PSAI exams had questions regarding gas planning for expeditions. Speak to your instructor, I'm sure they will help you go through it. Secondly, last year we took a twinset of 30/70. By decanting 75bar in to an e,pty twinset and topping with air to 210bar you'd get a 24/25 mix. Not exactly what you're after but it was good for us and is divable to 45m. Cheers/Nic __________________ "God will forgive them. He'll forgive them and allow them into Heaven. I can't live with that." The Other Place