Your idea of ideal twins

[doole]

...and no, I don't mean the kind of twins that have been sending you all those Email invitations to visit their web site. :07: (Actually, I mean doubles.)

I am about to engage in a tech course and I am considering the purchase of a pair of new bottles. I am looking for recommendations in terms of capacity and bouyancy characteristics.

I already own matching PST 120's, 3442 WPSI. These are great for use as singles but I wonder if they might be a bit much together. (Their land weight is kind of up there.) Moreover, I will still require a pair of tanks for use as singles during normal rec diving.

Thus there are so many options open to me that I'm a tad confused. Should I use the 120's as the doubles and get something else for rec use, or vice versa - get something else for the doubles and continue using the 120's for rec diving? (In that configuration, I like their bouyancy characteristics and the fact that I can often dive all day on one of them.)

Thanks in advance,
chris

 

[Boogie711]

Welcome to diving doubles. Start working out.

If you're doing technical diving, you're going to want the gas on your back. Which usually means weight. An option you may want to consider, depending on your gas needs, is doubled AL80's, especially if you're not doing longer (ie, open water) run times.

 

[jonnythan]

What does your instructor recommend?

 

[doole]

What does your instructor recommend?T

Good question but I haven't asked; he's out of town at the moment. (And I just now decided to go ahead and take the course.)

 

[sinkorswim]

Chris,

It looks like everyone buying new doubles is opting for the Pressed
Steel E-Series tanks. I still prefer the old LP104s because they're more
negative, but they probably won't be available much longer. If you find
a good deal on a set then go ahead and grab them while you can. The
better fill station operators are often willing to overfill the LP steel
tanks if they're in good condition and have a known history. Mixed gas
is priced per ft^3; I haven't seen anyone charge more for higher
pressures.

For tech diving the old 104s / new 130s are really the tanks you want.
But if you want to set up two sets, or want to ease your way in
gradually or want to use them for shore diving then the old 80s / new
E100s are the way to go.

Double Al 80s will also work and are economical. You'll need a V-weight
to counteract the buoyancy so they end up being just as heavy as similar
size steels.

And before you do buy a set make sure you're comfortable handling the
weight. A full set of double 104s with bands and manifold is about
110lbs. That can be a tough load for smaller divers.

 

[doole]

I'm certainly not a 'smaller diver' and not opposed to lugging around the weight when necessary. Just curious about people's preferences.

 

[gerardnealon]

I'm certainly not a 'smaller diver' and not opposed to lugging around the weight when necessary. Just curious about people's preferences.

I like the E8-130 pair. They are shorter then your 120 (dont quote me on this, but I think by almost 2 inches) but just a little wider. I am looking into a pair of those for myself. Good luck in your decision.

 

[sinkorswim]

I'm certainly not a 'smaller diver' and not opposed to lugging around the weight when necessary. Just curious about people's preferences.

Sorry, wasn't trying to make you sound small

How tall and how many pounds are you to get a better idea ?

 

[doole]

Sorry, wasn't trying to make you sound small

How tall and how many pounds are you to get a better idea ?

6'4" / 230. In my drysuit, with the 400g thinsulate and an al80, I just tie an anvil to my butt. (Actually, about 34 lb of lead, in fw. Please nobody get me started on taking off lead. I have light bones and large lung volume, ok?)

BTW how does the switch to doubles affect bouyancy characteristics? If they say the bottle is x lbs negative when full can you treat that as the weight coming off your belt, more or less?

 

[Dryglove]

If you go from a alm 80 tank to say a E7-100 you will drop a bit of weight from your belt. If i remember right E7-100's are -1 lb negative when near empty which is a difference of 5lbs from your alm 80(+4lbs). You will also lose a few pounds from the addition of bands, manifold and a second first stage.