What Size Stage(s) Should Santa Bring?

[warmwaterdiver]

Hi All

Doing my TDI Entry Level Trimix in the new year (because I'm starting to forget things below 40m ). My parents are buying me some (more!) dive kit. Existing stage is a steel 5, thinking this could make a drop tank? So, new stage(s), initially thinking 1 stage but is it worth getting 2, but do I go 7's or ALI40's? definately not ALI80's, they're just toooooo big

40 = 5.7litre @ 207 bar = 1150 litres approx
7 = 7litre @ 232 bar = 1600 litres approx

Remember I haven't done the course yet, but if I run a bottom time of say 40 minutes at 50m, END of say 30m (don't know what mix/deco that would give me?), would a single ALI40 be sufficient? (my SAC is 15 on a good day) Also take into account I like to be self-sufficient and hide away from all those box divers, they always look at me funny, on the last trip, I overheard one calling me his bailout

Cheers
G

[Paul Oliver]

I have 2 steel 7's and i'm very happy with them

Although i did a bit of playing last week and totally cocked it up

[Ferg3333]

Two sevens would balance well? If you decide to go on to full mix your all set

[daz]

Gary,

The only way you can honestly make the right decision is to work out what you require based on SAC, DECO obligations and stop depths. Are you planning to use it for 50%?

Daz

[NotDeadYet]

I'd go for a pair of ally 7's if you're planning on progressing further. AL80's are actually very comfy in the water but total overkill for most diving.

[warmwaterdiver]

Originally Posted by daz

Gary,

The only way you can honestly make the right decision is to work out what you require based on SAC, DECO obligations and stop depths. Are you planning to use it for 50%?

Daz

SAC is 15 on a good day

DECO, I dont know exactly but I'm not overkeen on huge amounts of deco, so would probably try to keep it to around 30min

if one stage, then 50%, if two, then 50% 80% presumabley

[Woz]

Well 20 mins deco on an AL40 with fiddy cent in it is very doable. And the 40 is a great size and has top buoyancy characteristics. If just bobble up behind your arm on the dive and you don't know it's there. It's about the same physical size as a steel 7. The AL80 is a big old boy. Have never dived with a steel stage so can't help you there.

[Al_Star]

Originally Posted by warmwaterdiver

SAC is 15 on a good day

DECO, I dont know exactly but I'm not overkeen on huge amounts of deco, so would probably try to keep it to around 30min

if one stage, then 50%, if two, then 50% 80% presumabley

A 7L will do me for 30 minutes of deco but that's at the limit of the gas planning rules I use (plan only 2/3 usage). Given what you are after a 7L sounds reasonable.

I bought an AL80 for my 50% stage as I find it sits better in the water than a 7L.

Cheers
Al

[warmwaterdiver]

I am presuming from Mr Nackers site, but we all talking about ALI 7's rather than steels, did I heard the new ALI7's are different to the old ones?

[up 4 it]

Based upon 40 mins @ 50m with a SAC of 15lpm you would have the following

Mix 23/33

Runtime 1hr 31 mins ( I would add an extra 10 mins @ 3m to this to add some conservatism)

Gas req
4488L bottom gas (not including any reserve) = x1.5
854L Deco gas (not including any reserve) = x2

If you were on a 50% deco gas you'd need 1290L x 2

You would really need to be on twin 12's with two x 7L stages to do that dive

Steve