What is the best way to start diving doubles?

[ElectricZombie]

If you could borrow a set of doubles to try out, that would be ideal. I would go with a backplate if I were you. The first time I tried a set of doubles, I borrowed a guy's "technical" BC. The rig was really sloppy and you can't make it fit right. My backplate setup is rock solid.

You don't need to take a course to dive doubles. Find a buddy who has been diving doubles for a while and get some pointers. Make sure you know how the valves work...that's the most important thing. When I started diving doubles, I learned how they operated...bought a set and dove them. I would rather dive doubles over a single tank anyday. I find diving with doubles to be easier than with a single tank.

 

[MikeFerrara]

Genesis once bubbled...
In fact, there is plenty wrong with double AL80s, not the least of which is that they are VERY butt-light and can make trim a real nightmare.

I haven't seen any one have this trim issue with 80's. And yes, I've seen plenty of divers using them.

 

[Genesis]

for just a couple of dives, and they immediately got turned back into singles.

The amount of weight I needed to have on my belt to compensate for the tanks was obscene, and I was horribly out of trim as well. I could have probably figured out a way to make them work, but why when I can dive balanced tanks that don't get so butt-light as they are breathed?

Some folks may like them, but I'm not one of them.

The C80s (compact 80s or "neutral" 80s) might trim out better for me, but I saw no reason to mess with those, given that they're WAY heavier (in land mass) than Steel 72s and the gas difference is pretty insignificant.

There is one other issue to be aware of with aluminum tanks - if you use SS bands (and essentially all are) you are creating a galvanic cell, and if used in SALT WATER this is a major problem over time, as the aluminum is sacrificial to the SS bands! Be VERY aware of corrosion concerns; I'd probably use some kind of insulating barrier between the bands and tanks to avoid this, make very sure it doesn't get breached, and beware crevice corrosion in that case as well.

 

[JohnF]

MikeFerrara once bubbled...


I haven't seen any one have this trim issue with 80's. And yes, I've seen plenty of divers using them.

The first time I ever dived doubles was with a pair of al80's in a cenote in Mexico. I got everything comfy and made sure I could get gas and jumped in. The trim was perfect from the gitgo. I won't say my buoyancy control was so hot at first but the trim was excellent.

Then I built a set of 72's at home and had a helluva time with being nose heavy. I was almost tempted to use ankle weights before I got it resolved. (note I said almost) But the 72's are nice to lug around, especially for an old fart with creaky joints.

John F

 

[Don Burke]

Genesis once bubbled... for just a couple of dives, and they immediately got turned back into singles.

The amount of weight I needed to have on my belt to compensate for the tanks was obscene, and I was horribly out of trim as well. I could have probably figured out a way to make them work, but why when I can dive balanced tanks that don't get so butt-light as they are breathed?

Some folks may like them, but I'm not one of them.

The C80s (compact 80s or "neutral" 80s) might trim out better for me, but I saw no reason to mess with those, given that they're WAY heavier (in land mass) than Steel 72s and the gas difference is pretty insignificant.

There is one other issue to be aware of with aluminum tanks - if you use SS bands (and essentially all are) you are creating a galvanic cell, and if used in SALT WATER this is a major problem over time, as the aluminum is sacrificial to the SS bands! Be VERY aware of corrosion concerns; I'd probably use some kind of insulating barrier between the bands and tanks to avoid this, make very sure it doesn't get breached, and beware crevice corrosion in that case as well.

My prime gripe with my AL80s is how much they make me weigh on the boat. Neutral 80s would be worse.

A steel backplate and jetfins seem to solve the trim problem if I put the bands a little lower on the tanks.

I use rubber splicing tape between my bands and tanks. There hasn't been a galvanic corrosion problem. I saw where someone cut strips from a bleach bottle to use as an insulator. I'm happy with the tape.

The AL80s were my first set of doubles. My first dive with them in a drysuit sent me scrambling for steel tanks.

 

[O-ring]

I have a set of double AL80s and use a 4# v-weight with them. No trim problems.. I also have a set of double steel 72s and use no weight with them. No trim problems.. I also have a set of double 130s...well, you get the picture..

 

[Genesis]

It all depends on you and what you're most comfortable with.

I hate AL80s, both as singles and as doubles. I simply don't like the "butt up" trim of them. They make great stages, but horrible backgas tanks.

But that's me - others have no trouble with them in that regard...

AL80s have exactly one good characteristic, IMHO - they are cheap.