Tank Boots, Boats and DIR

[Derek S]

Again, as I said, people hear what they want to hear and will do what they want to. I'm not saying anyone is wrong for diving steel tanks. AL 80s is what the NEUE has decided is the team standard. I agree and accept that standard. I will someday take cave classes and will own large steel tanks, but for now, AL80s are just fine.

Boots, ST vs AL, do what you want. I'm not policing anyone, and I'm surely in no position to tell anyone what they should be doing. A question was asked, and I answered it the best I know how. This is what has been handed down from the "GUE brass" as the current train of thought.

As usual, a bunch of people interjected their personal thoughts and feelings into it. That is fine and good, but why ask for an answer to a question (in a forum as specific as DIR) when you're just going to dispute it anyway? Either pony up the money for an electronic membership to GUE, subscribe to the Quest list and search the archives, or e-mail JJ and ask him yourselves.

I'm not specifically replying to Aaron (Soggy), but since he brought it up:

-cheaper...true, but you need multiple sets to do a single day of diving, thus you are back to spending more money than on a single set of 130s. That, combined with the fact that they are much less durable and have to be replaced more often makes this point completely null and void..

I can purchase 2 complete sets of AL80 doubles for what it will cost me for 1 complete set of PST 130s. This means I have the resources available to do those 4 recreational limits dives (I'm not trained for deco yet), or better yet, I have the team resources available if something goes horribly wrong and I need to loan out my extra set of doubles to a teammate if their gear goes south. Isn't that what one of the main tenets of DIR is? Team diving?

-easier to dive...I don't know, I never had trouble with my 130s.

True. Any diver should be able to dive any gear given enough knowledge and in-water time. This is a personal preference thing, but as always, GUE trained divers are taught to bring the right tool for the job.

-lighter...true, but I'm a skrawny chickenlegged guy and I can get myself up a boat ladder in 130s with a deco bottle on in rough seas. Also, at the expense of "lighter" you get less gas. If you want to carry more gas, the "solution" is to carry an al80 stage. Now we are back to the same amount of weight, still less gas, and you are a lot less stable both on the pitching boat and in the water. The argument here is, that you can hand the stage up, but good luck handing up an al80 to the boat when the seas are rough.

80s/104s/130s. When all is said and done (V-weight, ect), they are within a few 10-15lbs of each other (as complete doubles) and any diver considering using them should be able to heft them, so that is kind of a moot point. I'm just wondering where I'm going to need the extra gas....

AL80 (doubles) X 2 = 160cft
ST130 (doubles) X 1 = 160cft

-better buoyancy characteristics...that's pretty arguable. Considering the amount of useless lead you have to carry in cold water with a drysuit, I'd say that al80s have horrible buoyancy characteristics for anything but warm water 3mm diving or stages.

See RTodd's response.

 

[CD_in_Chitown]

Yeah right. Tank boots are like valve covers. You don't need them in the water so you don't take them.

Derek's post from Bob covered all of the other stuff really well but everyone seems to be missing the important thing Bob said which is that people latch on to generalizations and only hear what they want to hear. While some of the newer steel tanks work with drysuits als are a better choice for most open water dives. Balanced rig in a steel tank with much greater amounts of gas (weight)/ drysuit context here has more to do with the start of the dive and the ability to get neutral with a bouyancy loss than at the end of a dive.

See RTodd's response.

I did, but I don't see how it relates to Soggy's point.

 

[Soggy]

Again, as I said, people hear what they want to hear and will do what they want to. I'm not saying anyone is wrong for diving steel tanks. AL 80s is what the NEUE has decided is the team standard. I agree and accept that standard. I will someday take cave classes and will own large steel tanks, but for now, AL80s are just fine.

I understand the complete arguments very well and I think I addressed several of the points. The logic is flawed and al80s just don't cut it for anything beyond either very shallow or short dives.

What kind of dives is NEUE doing with the double Al80 standard?

I can purchase 2 complete sets of AL80 doubles for what it will cost me for 1 complete set of PST 130s. This means I have the resources available to do those 4 recreational limits dives (I'm not trained for deco yet), or better yet, I have the team resources available if something goes horribly wrong and I need to loan out my extra set of doubles to a teammate if their gear goes south. Isn't that what one of the main tenets of DIR is? Team diving?

My team dives 130s because on even a single, short profile to 150', they are real tight on gas.

I understand that you don't deco dive, but you might in the future and those 80s aren't going to serve much purpose until you are doing tech 2 level dives that require staging.

If you can do two *quality* (meaning come even close to the MDLs) rec dives in the 80-120' range on a single set of al80 doubles in cold water, you have my respect....you must have an amazing SAC rate.

I'm just wondering where I'm going to need the extra gas....

The first time you have a problem underwater that messes up your dive plan. It's called contingency and sometimes rock bottom isn't always going to be enough.

 

[MXGratefulDiver]

Unless you're cave diving or doing wreck penetration, AL80s should be your doubles of choice. Problem solved.

AL 80s is what the NEUE has decided is the team standard. I agree and accept that standard.

I somehow think there's a fairly broad contextual difference between these two statements ... and that the former is not universally applicable.

... Bob (Grateful Diver)

 

[StSomewhere]

I'm not sure I follow your question, it looks like Bob Sherwood's answer on the reasoning was provided in this thread.

Well I must've missed it then. Maybe someone can quote back where it says adding a bunch of non-dumpable lead to offset the buoyant AL80s is an improvement over a balanced rig, I guess I just don't see it... :06:

 

[CD_in_Chitown]

Well I must've missed it then. Maybe someone can quote back where it says adding a bunch of non-dumpable lead to offset the buoyant AL80s is an improvement over a balanced rig, I guess I just don't see it... :06:

Touche

 

[OneBrightGator]

The first time you have a problem underwater that messes up your dive plan. It's called contingency and sometimes rock bottom isn't always going to be enough.

Isn't that the idea behind rock bottom?

Also, ease in gas planning is a poor choice to dive similar tanks, gas matching is something every doubles diver should be able to do on the fly.

 

[lamont]

I wonder if this isn't another one of those east-coast DIR vs west-coast DIR issues ...

It definitely seems to be a SCRET vs. NE-UE issue.

Here's what I understand to be the major issues, with my thoughts:

1. Hit the gym and get your SAC rate down and stop using the 130s

- Fair enough, but I'm concerned that if a situation involves one or more divers under stress that SAC rates will rise substantially. I've taken this to heart and hit the pool and gone from .60 SACs on a good day to .45 SACs on a good day, but my bad days are still up around 0.75, maybe more conditioning will help -- still my gas reserves are going to be dictated by worst-case analysis rather than best-case analysis and it doesn't take much for Al80s to start looking kinda small...

2. Steels cost more than Al. Steels require frequent tumbling and cost more to maintain than Als.

- But I like the fact that steel metallurgically cracks much slower than Al and you'll see steel tanks being condemned due to rust before you see them failing VIP or hydro. Plus, I've got the disposable income.

3. Steels are harder to get balanced than Al

- This may be true if you're diving a 3mm wetsuit in fresh water. With my old, compressed 200g thinsulate, Al backplate, no extra weight in fresh water I think I'm a few pounds overweighted in E-series PST tanks. With the old 104s that are 5# negative when empty that'd be at least 10# overweighted when empty and 30# negative to start the dive which is clearly bad. With my brand new 400g thinsulate, though, in salt water I'm at 13# of weight to keep me down with 500 psi in steel tanks (I'm actually hoping the thinsulate compresses a bit so I can take some lbs off).

4. Steels are hard to get off the bottom

- With balanced steel 130s that were 2/3rds full of nitrox, a squeezed drysuit and a fully dumped wing I swum them up off the bottom in about 25 fsw of water without any issue. This is equivalent to tanks full of 30/30 or 21/35 and is around 16# negative so it seems pretty realistic. Now with double LP104s, fresh water and a 3mm wetsuit this test may have come out very different.

- Also, if you can balance the tanks, all that matters is swing. Underfill the double 130s to 2000 psi and they're no harder to get off the bottom than double Al80s.

5. Steels are a problem on pitching boats

- So far I haven't experienced any problems like this here in the PNW. Diving in the NE atlantic may be very different. Typically around here there's less than an hour to get to the dive site, conditions don't vary too much, and if the seas start getting bad you can find another site which is protected from the wind and dive there. It may be my my lack of experience, but locals don't seem very concerned about inclement weather, and 8 foot seas around here are extremely uncommon in general -- to say nothing of their chances of coming out of nowhere while you're on a dive.

6. Al trims out better

- No idea, but I'm gradually getting the hang of the steels. And going to 400g thinsulate tends to make your body more floaty and pushes against the tanks more evently and trims you out as well.

...

I've been weighing buying a set of double E7-100s/X7-100s vs. double Al80s for a small set of doubles, and while the double Al80s would be cheaper:

1. Literally nobody dives with double Al80s around here so matching would be out of the question, while you can find some double-HP100s or double-LP80s.
2. Total dry weight on land between double Al-80s and double steel-100s is within a pound or two.
3. I can achieve a 'balanced rig' with either set.
4. Underfilling the 100s to 2640 produces *exactly* the same buoyancy characteristics. Filling them up just results in starting the dive a few more pounds overweight.
5. It looks like i'd need some huge 15-18# v-weight for my 400g with Al80s. With steel-100s I keep the same weight configuration I keep with my steel 130s.

 

[Jason B]

But (and this was pointed out to me elsewhere) what is the reasoning behind doubled AL80s if you are just going to dive them with a 5 lb steel plate or an 8 lb v-weight (or both)?

What am I missing?

I'd like to hear this answer also.

 

[RTodd]

I understand that you don't deco dive, but you might in the future and those 80s aren't going to serve much purpose until you are doing tech 2 level dives that require staging.

If you can do two *quality* (meaning come even close to the MDLs) rec dives in the 80-120' range on a single set of al80 doubles in cold water, you have my respect....you must have an amazing SAC rate.

Why would you need doubles? You could do two MDL dives in those ranges on single 80s. You guys can use whatever steel tanks you want. However, the SAC rates bounced around here shed some light on the desire for huge tanks.