Tech 1 Cylinder Choices

[Rainer]

About to do my Tech 1 class, and trying to get sorted what cylinders I'll want to have afterward. So, a few questions:

(1) How many sets of doubles are people happy with if trying for 1-2 T1 dives/month, plus 4-12 recreational dives/month (most of the latter would be on singles, but would like to maintain the possibility of doing some in doubles without having to dump gas)?

(2) How many AL40s are you happy with? Just one? One for 50%, one for O2? More in case doing two dives in a day?

(3) Any use for AL80s at this point? Currently have two, but don't know if I'll need them for anything or whether I should just flip them (they aren't being used). I will NOT be considering Tech 2 anytime in the next five years...

Thanks.

 

[limeyx]

About to do my Tech 1 class, and trying to get sorted what cylinders I'll want to have afterward. So, a few questions:

(1) How many sets of doubles are people happy with if trying for 1-2 T1 dives/month, plus 4-12 recreational dives/month (most of the latter would be on singles, but would like to maintain the possibility of doing some in doubles without having to dump gas)?

(2) How many AL40s are you happy with? Just one? One for 50%, one for O2? More in case doing two dives in a day?

(3) Any use for AL80s at this point? Currently have two, but don't know if I'll need them for anything or whether I should just flip them (they aren't being used). I will NOT be considering Tech 2 anytime in the next five years...

Thanks.

I think you need
- 3 sets of doubles (ideally) because at first you will not use a bottom stage and so will probably need 2 sets of doubles for 2 T1 dives (if you never do 2 dives on the same weekend you may get away with two). Around here, a trimix fill takes a few days in general, so getting a fill for a dive the next day is not that practical.

So 2 sets for trimix and one set with 32% is a good option (the 32% ones can be smaller)

Generally I use about 100-120 cft of backgas for a T1 dive (150-160 feet with 30 mins deco) so LP80's, L85's and up are fine for this range.

- To start with, 2 AL40's (70 foot bottles) as I think you only will be using a single deco bottle per dive. You probably wont get 2 dives out of one bottle with enough safety margin. 2 deco bottles is generally Tech1.5 or Tech 2 area

You may want an AL40 of 100% for emergencies (on the surface/boat if not supplied by the boat owner)

- AL80s can be useful in that once you get 20 or so T1 dives under your belt, you can use an AL80 of bottom mix and get two dives (or more) from one set of doubles.

This is a bit of a quandry though as for me
- the AL80 is a pain to swim around
- technically violates my training (1 slung bottle)
- adds complexity

but can definitely be a big benefit

You can also use them on a second dive -- do a T1 on the doubles and take an AL80 of 32% for a second recreational dive (great for RIBs or small boats etc.)


NOTE: I am defining "tech1" as per GUE (and some others)
Dives in the 150-160 foot range, single slung bottle (either 50% or 100%), max 30 mins of deco. Trimix used deeper than 100 feet, PPO2=1.2 END=100 feet

for anything else, your mileage may vary!

 

[MonkSeal]

About to do my Tech 1 class, and trying to get sorted what cylinders I'll want to have afterward. So, a few questions:

(1) How many sets of doubles are people happy with if trying for 1-2 T1 dives/month, plus 4-12 recreational dives/month (most of the latter would be on singles, but would like to maintain the possibility of doing some in doubles without having to dump gas)?

(2) How many AL40s are you happy with? Just one? One for 50%, one for O2? More in case doing two dives in a day?

(3) Any use for AL80s at this point? Currently have two, but don't know if I'll need them for anything or whether I should just flip them (they aren't being used). I will NOT be considering Tech 2 anytime in the next five years...

Thanks.

(1) One set is enough if you have time to re-fill it between dives.

(2) I have one AL 7 lit (for 50%) and one AL 40 (for O2). If you have enough time to fill twinset then you have enough time to fill deco tank.

(3) AL80 can be used for 50%. Two AL80s can be used to form another doubles.

Using two AL40 for deco and two AL80 for another doubles you can have complete two sets of tanks for T1 dives.

 

[MonkSeal]

... you can use an AL80 of bottom mix ...

NOTE: I am defining "tech1" as per GUE (and some others)

These two sentences are in contradiction

 

[limeyx]

These two sentences are in contradiction

yah yah, so sue me.

 

[rjack321]

HP100s are really the only way to go. Some people like the 119s and 130s but both of these pose issues of size and weight and are pretty overkill for a T1 dive in the 140-160ft range.

I have an AL40 of O2 but its a rare dive that I use it on.

I have 2 AL40s of 50% but for a couple years I only had one. Worked fine. Depends on what kinda charters you are gonna be one (2x T1 dives or a T1 + a recreational dive).

Given what you have now:
Setup 1 AL80 for 50%. This is good for 2 dives
Setup one AL80 with 32%, this is good for a 2nd recreational dive after a T1 dive on the same day
Get 2 (or 3 if possible) sets of LP85s/HP100s
Get one AL30 or 40 of O2

Down the road get somemore AL40s for 50%. Early in your T1 career its more important to have multiple sets of doubles for various mixes than it is to have multiple deco bottles. Cause you'll have 5 possible mix choices and one set of doubles is not going to cut it. 32%, 25/25, 30/30, 21/35, 18/45. I only have 2 sets of doubles but can fill at home and not go through alot of shop hassles.

 

[cfenton]

HP100s are really the only way to go. Some people like the 119s and 130s but both of these pose issues of size and weight and are pretty overkill for a T1 dive in the 140-160ft range.

I would have to disagree with that. Depending on your SAC rate and bottom times it very much possible to get two T1 dives out of a set of HP 130s. Still, at least two sets of doubles is very useful. I use 130s and AL80s which are somewhat compatible for gas planning.

1 AL80 or 2 AL40 for 50%

1 AL40 for 02. I will often used 100% inplace of 50% for the shallow (100' average) wrecks we have around here. Plus its good to have around on the surface.

1 AL80 for 32%. We use them often if we are doing a T1 dive followed by a min deco dive.

 

[rjack321]

I know plenty of people who have gotten the 130s but now either have back problems or just don't enjoy using them. Hasn't happened to any of the folks I know diving lp85s or hp100s. For me the issue isn't so much "can I get 2 dives out of one set of doubles" its how to manage the various mixes I might use in the course of a month or 2 (without dumping any gas). BTW, I also think the smaller doubles are easier to learn on. But I'm not 100% sure that's true, just a suspicion.

 

[JeffG]

BTW, I also think the smaller doubles are easier to learn on. But I'm not 100% sure that's true, just a suspicion.

I found my Al80's way easier to dive than my 130's.

 

[cfenton]

My first set of doubles were 100s; I hated them. I found that they had a tendancy to stand me on my head which may be a result of my height or just the fact that I was new to doubles. So I melted down my v-weight and made a tale weight. Still wanted to stand me on my head. I traded them in for a set of 130s and I've never looked back. The weight of the tanks isn't really a big issue for me but I can see how it easily could be. For smaller tanks I prefer Al80s; and I agree they are much more fun to dive than the 130s. Although weight belts are a pain in the ass.

Also, managing the various mixes without dumping isn't really a big issue for me as I have gas and a booster in my dive shed.