Need advice on setting up twins

[Jim Lapenta]

Find an instructor who can fill in all the blanks that seem to be present. Diving deep just for the sake of diving deep is not a good reason to go to doubles. First thing is to work on your basic skills and get your SAC rate down. Then once you have it where you want it get a bigger single cylinder like a 119 or 120. Or go to a LP 95 if you can get good fills. Couple that with an H valve and maybe add a 30 cu ft bottle. Work with using the slung bottle with a good mentor or experienced tech diver who uses stages. Believe me I learned the hard way that teaching yourself to use a stage is possible but not optimal.

Now what tables are you using to plan these dives and how close to deco are you comfortable coming to? Adding doubles without the knowledge of how to properly plan or do a decompression dive is just plain dumb.

No nice way to put it because doing stuff like that gets people hurt.

What deco profile will you use if you exceed your run times?

What are you using for planning these dives in the way of decompression tables or software?

What kind of contingency plans are you cutting?

What is the deco requirement if you exceed your NDL by 5 minutes, 10 minutes, or more? Doubles may allow you to do that.

What kind of narcosis management are you using?

Not trying to be smart assed but these are questions you need to have answers to before you start down this road. And as Andy pointed out if you are using terms like cheap, inexpensive, easier, etc. I'd advise you to get some more training and save up a buch of money before you head down this road. Cheap and easy can get you hurt or dead when it comes to entering the technical realm and if you are doing any kind of penetration or deeper longer duration dives that is what you are talking about. Neither is to be approached lightly or without serious thought as to the consequences of going cheap or easy.

 

[TSandM]

For considerably less money, you could scale up to larger single tanks. You can do just about any dive within no decompression limits on an HP130, and if you want redundancy, sling a pony bottle.

 

[DaleC]

For considerably less money, you could scale up to larger single tanks. You can do just about any dive within no decompression limits on an HP130, and if you want redundancy, sling a pony bottle.

Did I hear right? First sidemount and now this

It is true. I dive independant doubles (mainly 72's) but many of my buddies dive 130's with ponies. We do the same profiles. They may even have more usable gas than me as I need to reserve rock bottom in both tanks.

Narced, If you can't double up tanks at the moment you can still work towards your goal by increasing your dive planning skills. Try creating specific dive profiles and doing all the calculations and then see how close you come to actually following them.
It is a skill that will serve you well as you begin thinking of deeper profiles.

 

[TSandM]

I reluctantly came to the conclusion, some time ago, that people who are forced to dive with unknown buddies on a regular basis (people who travel alone) may well be better served to carry a pony, than to depend on their buddy to carry their spare gas. In an ideal world . . . but we don't live in one. Well, maybe I do -- at least until I take up this sidemount nonsense

The OP has said before that he has a tech diving friend (or tech instructor, I can't remember which) with whom he is diving, so he has access to better close-up advice than we can give him.

I think, from what he has posted in the past, he'd be better served with a large single tank and a lot more diving, than an early transition to doubles.