are double 80's dangerous?

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A few comments from my recent transition to doubles. In SoCal I dive my double HP-100s in drysuit with a Halcyon 40 lb. wing. Weighting is 6 lbs. BP plus 3 lb. tail weight plus can light plus 7 lbs ditchable. This gives me a balanced rig in cold water - that is the most important point. Also it gives me redundancy wrt inflation (wing and DS).

In Key Largo recently I was forced to dive with rental double Al 80s. My solution was to dive dry using a minimal undergarment in 77 F water and instead of the 3 lb. tail wt. use a full 8 lb. V-weight on the tanks plus ditchable as needed to hold a 10 ft. stop at 500 psi. Also a balanced rig with redundancy and appropriate for the circumstances. Some people will not dive doubles wet and count me in that group if the water temp. will permit diving dry (under ca. 82 F for me). A bigger obstical to diving dry could be very warm air temperatures - but we get that in SoCal too.

If you get your rig balanced and are happy with your other choices you will immediately see a vast improvement in stability and trim. Learn your valves ASAP.

Also make sure your hoses and regs are done right.

Jim
 
I agree... if you are going to use 'em, set 'em up right AND learn how to use the valves.
 
Stephen Ash:
Ah... this is what fools most people.

The bands and manifold plus two regs are enough to offset the positive bouyancy of the cylinders. In fact... in fresh water, for example, a set of [nearly empty] banded AL80's with regs attached (but backplate and wing removed) is about 2-4 pounds negative.

A diver who needs 6 pounds for a single Al 80 very likely will need only 2-4 pounds if he twins up.

Many of us don't use any weight with Al80 doubles.

edit: [nearly empty] inserted
I get your point.:blinking:
That's however additional weight no matter where it comes from, and that why it's not necessary to count with any difference from other ballast.
 
Icarusflies:
Thank you for the feed back;

Yes, I am talking about AL 80.

What is really motivating me is that I dive with my father who has not the best air consumption so our dives are cut short. We use HP 100 cuf, so it was either getting bigger tanks (120 or more), which I don't think is a good idea because of the negative qualities of such big tanks when diving wet or get a set of double AL 80's which, correct me if I am wrong, will have a better buoyancy qualities than big steel tanks and better trim.

I don't plan to touch the mainfold underwatter unless there is an emergency treating the twins as a single big tank. The redundancy is nice tho.
Is your father switching to doubles too?
 
Stephen Ash:
Ah... this is what fools most people.

The bands and manifold plus two regs are enough to offset the positive buoyancy of the cylinders. In fact... in fresh water, for example, a set of [nearly empty] banded AL80's with regs attached (but backplate and wing removed) is about 2-4 pounds negative.

A diver who needs 6 pounds for a single Al 80 very likely will need only 2-4 pounds if he twins up.

Many of us don't use any weight with Al80 doubles.

edit: [nearly empty] inserted

I will agree with Stephen and Peronne, I DID drop weight with AL80s. I really enjoy swimming with them.
 
The guy wants to use doubles because he wants more air and really likes the redundancy and the associated safety. Then in the next sentence he says that he will not touch the manifold.

What redundant function does a manifold provide if the diver can not (or will not)operate it? At the very least, it is more complicated and increases the likelihood of a failure and a gas loss (due to two regulators and two or three valves etc).

Some day I need to take one of those tech courses and learn about this stuff
 
I like my doubled AL80's. Some weight came off the compared to diving a single AL80. The rig is not too heavy when walking to or from the water.
 
Pengwe.....Yes, my father and I will be diving doubles.

Dumpster.....I ll clarify, I don't plan to do valve drills until I get into GUE dundamentals, in the mean time I get redundancy from the 2 first stages and safety from the additional gas.
 
Icarusfiles,

Please don't wait until fundies. Learn to manipulate your valves on land. Doubles are NOT redundant unless you can manipulate the valves. Without that, they are theoretically, more likely to fail than a single tank.
 
What he said.

You shouldn't need fundies to learn how to use this stuff. If you do, then you would be wise to not use it until you have some training.

Do some self study. Ask around. Get a mentor.

Diving blind with this gear is asking for trouble. Heck... you can screw things up before you even get in the water.
 
https://www.shearwater.com/products/perdix-ai/

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