Setting up twin set for wife, Standard AL80 or Compact/neutral 80?

[stuartv]

she has expressed interest in backmount doubles for intro to tech and so we can stay down longer together without having to go back up for her to swap tanks.

What kind of dives are you doing where she can stay down longer without going into deco? Is her interest in actually going beyond ItT, to take AN/DP?

To me, doubles aren't that useful unless you're either diving pretty shallow (thus, very long NDLs), OR you are doing decompression dives.

 

[Marktan]

What kind of dives are you doing where she can stay down longer without going into deco? Is her interest in actually going beyond ItT, to take AN/DP?

To me, doubles aren't that useful unless you're either diving pretty shallow (thus, very long NDLs), OR you are doing decompression dives.

Currently we're realtively shallow, so long NDLs in the quarry or on the shallow wrecks of Lake Michigan. She has, however, pleasantly suprised me with an interest in learning AN/DP as well as getting both of us onto an eCCR thanks to the TDI Mission Tech demo event; A pair of SF2's will be in the future, I'm sure, once funds allow.

We are both wanting some deeper/extended dives on some other wrecks, as well as for travel (assuming equipment is available). For instance, she specifically wants to drive down to Pensacola and dive the Oreskeny and some of the wrecks off the Carolina coasts. We've had the opportuity to not only meet but sometimes hang out with some industry greats and it just gets her excited to do more. After talking to them, she is greatly inspired the women in the dive industry such as Jill Heinerth and Marissa Eckert (Waltman). We also have several dive friends that do more tech dives, including deep wrecks, caves, and rebreathers, whom we would like to be able to dive with in the future.

We will both begin our year of divemaster training/candidacy in January (dual SDI/PADI), probably knock out our SDI-Solo as well in April. From there, add TDI Intro to Tech, AN/DP, Cavern, and Intro to Cave somewhere along the line depending on time (we're in no hurry), and progress from there. Also, since we are down in Mexico every year around that same time, we have interest in doing the Cave Camp down in Tulum if we can manage getting certified ahead of time. But these are goals, and certainly a lot of practice dives need to be done in between. Not expecting to get it all done at once; and yes, drysuit is an eventuality.

Bottom line is that I have the extra tanks. I just picked up the doubles manifolds, valves, and bands (she doesn't know that part yet...Thinking setting up the tanks and putting them under the tree for Christmas). I just need to get it assembled, hence the original question of AL80s or CF80s for the time being.
Most responses both on this board and privately are leaning towards the Neutral 80s.

 

[guruboy]

Something else to consider is the BC wing design. I use a BPW and my doubles wing is wider than my singles wing. This is to keep the double tanks from limiting the expansion of the wing (aka the lift).

So you might want to do some quick math and measurements to verify the lift vs weight of her final rig.

 

[Marktan]

Something else to consider is the BC wing design. I use a BPW and my doubles wing is wider than my singles wing. This is to keep the double tanks from limiting the expansion of the wing (aka the lift).

So you might want to do some quick math and measurements to verify the lift vs weight of her final rig.

Thank you, I'll double check this. I know it's got 40lbs of lift with the bungees removed and allowed to inflate fully. She was ok when she tried the twinset 108s on the same BC last year, but we will confirm measurements.

 

[211ratsbud]

The benefit of the neutral tank is you need less weight at the empty (like 500ish) tank test in shallow water. I think given the circumstances the neutral tank makes the most sense. You can always put a cam band and a trim weight if needed. Her overall lead# should drop. 7mil wetsuit should work well with the double aluminium tanks. It's usually acceptable to dive wet and aluminium doubles, granted the water conditions permit. Be sure to assess your deco bottle balance in the same manner when that time comes.

 

[Marktan]

The benefit of the neutral tank is you need less weight at the empty (like 500ish) tank test in shallow water. I think given the circumstances the neutral tank makes the most sense. You can always put a cam band and a trim weight if needed. Her overall lead# should drop. 7mil wetsuit should work well with the double aluminium tanks. It's usually acceptable to dive wet and aluminium doubles, granted the water conditions permit. Be sure to assess your deco bottle balance in the same manner when that time comes.

Thank you!

 

[sigxbill]

Like @LiteHedded wrote - with a 7mm suit you should go with the AL80s for the doubles. Nothing else matters ...

 

[Michael Guerrero]

Because you're diving 7mm and she needs 12 to 14lbs, I'd look at HP100s if she's short, or LP85s if she's not. Steel backplate, and she might just get away without having to add any more weight.

 

[Michael Guerrero]

Agree about the characteristics, but own the 80s now, and have several upcoming certs for the two of us that funds are being allocated to (not to mention a replacement for my recently flooded and now dead camera), so unless I find a great deal on a pair of 100s, no go for the time being.

Check the classifieds for the used tanks, they're on there. And the 80s make great deco or stage bottles.

 

[Marktan]

Sorry, haven't been on SB in a while, just updating on the setup we wound up with.
Doubled up the two Catalina Compact/Neutral 80s [3300psi, -5.9 lbs full and -0.2 lbs completely empty (tank only)].
Highland SS bands.
Halcyon 300bar DIN valves and isolation manifold.
Managed to keep it hidden and presented to her on Christmas.