Tech 1 Cylinder Choices

[limeyx]

Thats because it depends. Every "tech" trip I have done, we fill tanks in between dives, so only one set is needed.

Depending on the boat and the number of divers, it might be hard to get two complete sets of gear onto the boat.

That might lead someone into using stage bottles for bottom gas and trying not to use their backgas. Again...you could do 2 dives using two stages and your back gas...but if you confine yourself to "tech 1" blinders...then you wont be doing that. LOL

In LA, unless you bring a "rich" trimix for dive1 that you can top with air/32% and still do a T1 dive, you will not get a fill on the boat, so you need to bring all your gas unless you are doing a multi-day and bring your own He (and probably nitrox)

This means 2 sets of doubles, AL80 stages (and say to heck with the "limits" ) or just one tech dive per trip.

 

[Rainer]

LA: 90% of boats are recreational only. Many of them are singles only.

Of the boats that will let you tech dive, you can usually bring whatever you want, but sometimes the 130's are best for the 6-packs as there is simply no room for 2 sets of doubles (so either 130's or an AL80 stage for one dive)

Sometimes we use an AL80 of 50% to save room too, but this is more bulk to drag around.

Most charters you can tech dive on are either 2 T1 dives only, or very occasionally 1 T1 followed by 1-2 recreational.

For beach diving usually singles is plenty, or a small set of doubles (LP80/85 or HP100) is more than enough.

One T1 per outing gets expensive at $175 + tip for the boat, but we may have access to more boats if we can reliably get more people signed up.

Get in contact when you get here and we can go dive -- my T1 buddy list is getting shorter not longer these days.

Pricey. The MA boat most of us use is $70/trip+tip (again, really for one T1 dive); max one set of doubles, but multiple stages/deco bottles are fine.

I think I'll start with the following, as it means I need the fewest "additions":

LP85 doubles (have these)
HP100 doubles (need one HP100, have bands and manifold)
AL40 (have)
AL6 (have)
AL80 for 50% (have)
AL80 for stage (have)
HP100s for singles (have)

Would be nice to add another set of doubles and another AL40, but hopefully the above is good enough for a bit. Thoughts?

Limeyx, I'll definitely get in touch when I've gotten settled in (early July). Will obviously still be very much cutting my teeth of T1 dives.

 

[MattL]

In La at frist I did the chaters 1 t1 dive and one rec till i could get 2 sets of dubs and 2 deco bottols.
Now i have 3 sets of dubs 2 al 40s and 1 al 80 the al 80 i use for all kinds of things bottom gas 50% so i keep it o2 clean then i rent a 100% o2 one for 100 ft less dives and i still havnt done a t2 dives yet and more then liky wont till next year but when you get out here i know lots of gue t1 and ag t1 divers so youll have lots of buddys to dive with there a a few shops that fill trimixs the shop i use you can get same day fills or next day others take up to a week some are flat and some are bye the cuft send me a pm for more info

 

[rjack321]

I started with less than that. Depends on how many T1 dives you can drum up per month (and afford). You might consider a second AL6 to go with the 2nd set of doubles. I've only used air in LA, its not that cold at all - despite Limeyx's whining

 

[limeyx]

I started with less than that. Depends on how many T1 dives you can drum up per month (and afford). You might consider a second AL6 to go with the 2nd set of doubles. I've only used air in LA, its not that cold at all - despite Limeyx's whining

heh, 1 AL 6 is plenty for me.

I somehow have 5 sets of doubles but 3 is perfectly fine.

 

[limeyx]

Pricey. The MA boat most of us use is $70/trip+tip (again, really for one T1 dive); max one set of doubles, but multiple stages/deco bottles are fine.

I think I'll start with the following, as it means I need the fewest "additions":

LP85 doubles (have these)
HP100 doubles (need one HP100, have bands and manifold)
AL40 (have)
AL6 (have)
AL80 for 50% (have)
AL80 for stage (have)
HP100s for singles (have)

Would be nice to add another set of doubles and another AL40, but hopefully the above is good enough for a bit. Thoughts?

Limeyx, I'll definitely get in touch when I've gotten settled in (early July). Will obviously still be very much cutting my teeth of T1 dives.

List looks decent. Almost everyone here uses Al40's for 50% whenever possible as the 80 is a pain to haul around (we can get some current on the local wrecks).

If we can get 8 or so divers, we can take the slightly bigger boats with less costs.
Also, we have a 6-pack boat that really takes 4-5 t1 divers thats a bit less expensive but we need to make sure we can fill it or it gets expensive.

There is some pretty good T1 diving down here on both reefs & wrecks.

 

[jjones9527]

Our baseline for Tech dives is the Jodrey in the St Lawerence. For a Tech 1 dive (up to 170 for 30 mins) we use 130's of 18/45 and an 80 of 50%. This setup basically covers all T1 dives that we may do. For us, a 40 is useless for a deco bottle, and 80's are border line for back gas. It basically comes down to doing the math, finding out what you need for gas + reserve, and selecting tanks that match you diving. For us in the great lakes and St Lawrence river, that basically means 130's for back gas and an 80 for deco for dives in the 130-170ft range. For shallower stuff double 80's and a 40 will suffice. This is just a general guide line, you can easily do the math and find out how much gas you need to do a dive, and which tanks will let you carry that amount. My prefs are 130's or 80's for back gas, and 80 or 40 for deco, depending on the dive.

 

[limeyx]

Our baseline for Tech dives is the Jodrey in the St Lawerence. For a Tech 1 dive (up to 170 for 30 mins) we use 130's of 18/45 and an 80 of 50%. This setup basically covers all T1 dives that we may do. For us, a 40 is useless for a deco bottle, and 80's are border line for back gas. It basically comes down to doing the math, finding out what you need for gas + reserve, and selecting tanks that match you diving. For us in the great lakes and St Lawrence river, that basically means 130's for back gas and an 80 for deco for dives in the 130-170ft range. For shallower stuff double 80's and a 40 will suffice. This is just a general guide line, you can easily do the math and find out how much gas you need to do a dive, and which tanks will let you carry that amount. My prefs are 130's or 80's for back gas, and 80 or 40 for deco, depending on the dive.

170 for 30 is not what I would honestly say is within GUE tech1 limits (which I think the the class we are discussing here)

This is why the 40 is "useless" as it's designed for max 30 mins deco (or 26.4 mins)

 

[jjones9527]

How much contingency gas do you have with 30mins of deco on that 40? (I'm too tired to work it out myself right now)

 

[limeyx]

How much contingency gas do you have with 30mins of deco on that 40? (I'm too tired to work it out myself right now)

The guy sitting next to me at 70 feet's bottle, backed up with 40 cft of each of our backgas (out of total reserve of 64cft)

lost deco plan: double time at 70,60,50 feet (50 optional) 1 buddy on the bottle, one off.
both go to backgas at 40,30,20, double the stops (40 cft of BG is plenty for 20 mins at average = 20 ish feet)

- smaller bottles to lug around
- easier to add an AL80 of backgas (yes, violating our T1 limits)
- less temptation to go to 40,50,60 mins of deco "because we have the gas" when it's way better to go to 2 deco gases and add the O2

not slamming anyone for stretching their limits, just saying is all.

And there is nothing wrong with 130's in LA, just they are a pain to lug around, and only "needed" for deeper 170+ stuff.

yes, some can get 2xT1 dives off the 130's, but I have to cut the 2nd dive shorter or shallower to do so honestly.

80's might be a bit marginal for the 160 dives here, and 85's or HP100's would be better, and once you get more comfortable, the 80/85/100's are just fine and not too heavy.

EDIT:
If you mean margin in the 40 for a non-lost gas scenario, then.
0.5cfm * 2 ATA = 1cft/min (deco is average 30 feet), so in theory I should be able to do 30 mins deco on 2000 psi out of a 40. In reality I usually use a little more than that, maybe 22-2400 under reasonable cold water/stress.

Plus I have the remains of my backgas which at 20,10 feet is almost as good as the 50% anyway as we are using the gradient, not the PPO2 to deco