Going doubles - questions

[limeyx]

Jeff,
If your heading down the road to tech I would not bother with the 80's. Go right for the 120's or 130's. This is good for tech diving and also works good for 2 tank rec dives.
Pat B

Double 80's should be perfectly fine for dives up to say 150 feet for 25 or so minutes as long as you are really getting 80cf per tank. With HP-80's (at least around here), chances are you are getting less than that.

Also, the HP-80s are quite short, and can lead to a lot of head-heaviness.

120's are *reallllly* long tanks, probably best for especially tall people.

130's trim out really nicely, but as others have said are really overkill except for a "big" dive.

 

[limeyx]

Thanks everyone.

As for what we are going to be doing - That is clear in my original post - We are looking to have enough gas to do some deep diving to 130 feet, within NDL, and have enough reserve gas to surface with safety stops if one buddy has an OOA situation at depth. We'll also likely be using EAN 28%.
...
Jeff

I would really recommend taking a deeper diving class to do dives in the 100-130 range. A deeper 'recreational' class that will let you dive 30/30 or 25/25 triox will greatly enhance your safety and comfort at those depths.

Nick

 

[Otto]

I suggest that you log in to thedecostop.com and look around before you spend any money. Then look at techdivinglimited.com. Look at the lower left corner of the main page for cylinder specs. Lots to learn there. Note that the length of the cylinder in relationship to the length of your torso will have much to do with your trim, and that there are many choices in tank dimensions / boyancy characteristics for any given tank size. Before you select a tank you also need to ask yourself where you are going to get them filled, and can you get HP fills there? Also if moving twords trimix how will you get that? When moving to doubles think about physical fitness. Back strength in particular and over all fitness in general as you will end up going deeper, longer and more often in the near future. Since it sounds like you have a steady dive partner it would be nice to match your air consumption rates/cylinder sizes so that you can have the same bottom time, and that the lowest gas user has enough reserve for the greater gas user. If you have the ability to use them bigger is better. I often get 2 or 3 dives off my lp120's with a solid fill. If there is any way possible I would try to find a dive buddy or dive shop to let you try/borrow/rent some tanks and dive them in a pool 3 or 4 times minimum before you buy. When buying your gear if you can get a bunch at once all at the same location I wouldn't hesitate to hit them up for a package deal.

 

[tonka97]

I've just set up twin al 80's.

Pretty darn heavy; A lot of force on your neck and shoulders!:11:

I wouldn't want to deal with more weight than this...would seem too much like WORK not play!:shakehead

 

[JeffG]

I've just set up twin al 80's.

Pretty darn heavy; A lot of force on your neck and shoulders!:11:

Are you kidding me. Those are light. Try twin 130's.

 

[SparticleBrane]

I thought a single Al80 was heavy when I first started diving but now it feels light. It's all about what you get used to. Double Al80s aren't really that bad.

 

[Jim Lapenta]

I'm having a set of lp 72's O2 cleaned and put together as I write this. The shop is also cleaning my al 40 and lp95's. I have the bands and manifold for the 95's but have decided to dive the 72's to get used to doubles. I'll put the 95's together when I start my intro to tech and Heliotrox later this spring. The naui shop I've contacted recommended this route for the type of dives I want to do intitially and the instructor has a great reputation for his tech classes. I'll be using the 72's for shore dives initially and the 95's as I get further into it but will most likely be doing boat dives or shore at a different location than usual since I would not want to get into the water where we do now with 2-95's on my back. The entry has been really tore up by the weather this year and unless I use the boat ramp climbing into the water could be very dangerous. I have two of the HP 80's and decided against doubling them due to the shortness of the tanks and putting too much weight high up. If you are going to do steels get a set of lp 85's. Nice length, full fills easy to get, and "good" fills can give you as much air as a set of 105's. If I did not already have 8 full size tanks, 2 pony's and two argon bottles I'd get a set. I still may before the end of the year. Depends on finances and what my diving requires. But for now I figure aset of 95's for the first dive of the day and the 72's for the second once I get comfortable in both will be just fine.

 

[jduncan]

Thanks again everyone.

So after some more reading here and on the Deco Stop forums, I've narrowed it down a bit.

What do people think of the Faber LP 85's for a doubles setup. Jim, I see you are recommending that type of setup. They look to be an ideal setup for what we need.

Anyone care to comment on those?

They are 26", neutral empty, -6 full, and weigh 31 pounds empty. Seems like a pretty good match.

From what I have read and calculated, the HP100's I have are going to be too much weight, and the E7-80's I was considering may be tough to trim out.

Thoughts? I know this is getting long, but I want to make sure we get the right setup.

 

[Jason Ooi]

Hi jduncan, Sorry; I can't see your diving profile, can I ask what is your certification?
Hope you can have a right idea a good setup.

 

[jduncan]

NAUI AOW, Drysuit Diver, Nitrox, Deep Diver, etc. I have about 125 dives in a year and a half. Remember I'm not looking to get too technical. The purpose of the doubles is for some "deeper" cold water diving on charters where a reserve of 30CF is mandatory.