New Doubles

[jgarysmith]

Can anybody put there offer opinions on a double set up for dives not exceeding 130ft?Just looking for more bottom time. I currently own a Hp 100. Would it be a good idea to buy another and band them.

I am new to diving with doubles and get very confused with all the options. I dive wetsuits and a Mare Isotherm so I know that must be considered.
What about lp vs hp? Is the new E8 a good choice if used alone. :dazzler1: Help!!

 

[d33ps1x]

Can anybody put there offer opinions on a double set up for dives not exceeding 130ft?Just looking for more bottom time. I currently own a Hp 100. Would it be a good idea to buy another and band them.

I am new to diving with doubles and get very confused with all the options. I dive wetsuits and a Mare Isotherm so I know that must be considered.
What about lp vs hp? Is the new E8 a good choice if used alone. :dazzler1: Help!!

If you are diving mostly wet then stick with aluminum 80's doubled up. One of the problems with double steels is the difference in buoancy shift. You are talking going from REALLY negative to just slightly negative vs somewhat negative to positive with the 80's

In a drysuit if your BC's bladder goes you at least have the drysuit as alternate inflation. In a wetsuit at 100 feet if your bladder goes hopefully you can swim up your 20 lb negative steels with your wetsuit offering no buoyancy whatsoever. Also if you drop like a stone for some reason and start going down without keeping ahead of it good luck catching up at 140 or 150 in wetsuit alone with your inflator and your double steels.

Be safe. Read up on it. Im no expert so read some other threads on this.

 

[theskull]

Leave doubles for later. Want more bottom time?
1. Dive shallower.
2. Improve your buoyancy skills so you don't waste air in your BC.
3. Improve your breathing rate (relaxation) so your HP 100 lasts longer.
4. Buy a single LP 95 or LP 112 and "overfill" to 3000 psi. (Disclaimer--I would NEVER do this, LOL)

Doubles are a special tool for people moving into/toward tech diving, and require much additional skill (and money!) Not to mention effort and muscle to handle.

Dive singles for fun,
theskull

 

[jgarysmith]

Skull,
Thanks for the reply. Why would a LP 95 or 112 be better than a 100hp. Even if it is over filled to 3000, isnt a 100 still a 100 and a 95 a 95. Are LP tanks bigger, heavier, and taller than low pressure. I am not disagreing with you. Just trying to learn, I am still fairly a newbie. Not sure what is beter, LP of HP. Thanks gary

 

[jgarysmith]

Thanks for the info. Are 80 Alum a pretty common double setup ?

 

[d33ps1x]

Thanks for the info. Are 80 Alum a pretty common double setup ?

Yes. Quite common.

 

[Warren_L]

Additionally, steel tanks with larger capacities will have a greater buoyancy shift during a dive (if you draw down the air longer) due to the higher volume of gas.

 

[DEEPLOU]

Skull,
Thanks for the reply. Why would a LP 95 or 112 be better than a 100hp. Even if it is over filled to 3000, isnt a 100 still a 100 and a 95 a 95. Are LP tanks bigger, heavier, and taller than low pressure. I am not disagreing with you. Just trying to learn, I am still fairly a newbie. Not sure what is beter, LP of HP. Thanks gary

Most LP's are rated @2400 (2640)psi. So a LP 95 @ 3000 psi actually is holding about 107 cuft. and a LP112 is holding abt 127 cuft.
A HP 100 is 100 cuft @3500psi. So if you get a fill of anything less than 3500psi you have less than 100 cuft of gas.

My LP's seem heavier, but in water don't make difference.

Which is better?? Like many other options in diving, you will get arguments on both sides.

 

[d33ps1x]

Most LP's are rated @2400 (2640)psi. So a LP 95 @ 3000 psi actually is holding about 107 cuft. and a LP112 is holding abt 127 cuft.
A HP 100 is 100 cuft @3500psi. So if you get a fill of anything less than 3500psi you have less than 100 cuft of gas.

My LP's seem heavier, but in water don't make difference.

Which is better?? Like many other options in diving, you will get arguments on both sides.

Irrelevant confusion of the issue.

Read this chart below. Search the threads on this and find out that this confusion of tanks and re-explanation has been beat completely bloody and then ultimately to death.
http://www.tekdiv.com/cylinders.htm

At the end of the day the HP's are the newly rated, and in the case of a few cylinders, slightly altered, lp tanks of old.

This really boils down to what's in a name.

 

[wetbehindtheear]

Can anybody put there offer opinions on a double set up for dives not exceeding 130ft?Just looking for more bottom time... ...Is the new E8 a good choice if used alone. :dazzler1: Help!!

The E8-130 is an excellent choice for single-cylinder dives. I'm a bit of an air hog, and I find a full tank of 32% perfect for a 110' dive - i reach my NDL at about 800 - 1000 psi left in the tank - a fine safety margin for a 130 cu ft tank (equivalent to 1300 - 1600 psi in an AL80). Trim is good, and it's not too heavy to lug around. It's also not likely to be too heavy to dive safely in a wetsuit, as its around -11lbs full, and -1lb empty iirc.