Going to twins, best way?

[runsongas]

As long as you asked, IMO the much maligned back mounted independent doubles are the way to go. Here's why IMO:

ID's are more practical than SM for OW diving from shore or a boat. A personal preference mostly but I was more comfortable with BM, having tried SM with factory reps on several occasions.

If you dive BM now there isn't much to learn as opposed to SM. LDS and instructors don't like this part.

ID's do not require the large $$$ lay out that SM does. Depending how much gear a diver has accumulated ID's could have a very low start up cost. The LDS don't like this part.

ID's provide the diver with 2 independent bottles, built in redundancy no pony bottle required.

ID's are easy to handle on land because out of the bands they are of course singles.

ID's provides the diver with single tank use without owning many tanks and the cost that entails. (Hydros, VIPS. O2 cleaning.)

ID's eliminate the need for a manifold although not likely to fail, a possible failure point none the less, if for nothing else than O-rings. Divers with restricted shoulder mobility can appreciate this, I know I do.

A major downside is that the diver could be restricted to access to only 1 tank if a catastrophic failure occurs on the other tank. Attention to air management is required especially the last half of the dive keeping in mind that both tanks should not be drained past the point of providing enough gas for a safe return to the surface.

Good luck

I disagree that ID bottles are better than sidemount. you can leave them on while climbing boat ladders with safety clips. for six pack rhibs, unclip in the water, a lot of people doff the bcd when climbing back on a rhib in BM anyways. trying SM a few times is not enough to build proficiency yet, same as trying a drysuit for a few dives will not make you comfortable enough in it yet compared to a wetsuit.

SM costs about the same as the standard BM configuration. you have one extra spg and a left hand valve, but you don't need tank bands. a SM bladder is close to the cost of a doubles wing and the harness is fairly inexpensive if you put one together yourself.

SM is also redundant, easy to handle on land, and they can be used as single tanks too. SM is significantly easier to reach for valve drills or feathering compared to backmount doubles. depending on the valves used, ID can be harder to reach than a doubles manifold.

 

[lexvil]

For what it’s worth since the OP is all over the place in the excuses other than the “I just want to” which is good enough for me but my main suggestion is to make more dives before jumping to the next thing, be come truly proficient before switching things just for the challenge.

For the most part, other than the not strong enough, plenty strong but not as strong as other think oddity, if the OP is looking for deeper challenges learning side mount may really be the best thing for him, having to fidget with the tanks to keep them trimmed may the perfect distraction on the dive and the modularity of it can ease whatever weaknesses he has out of the water.

In the meantime another “same” tank will lessen the fidgeting while changing tanks and they can easily move to side mount use later.

 

[BlueTrin]

I use twins 12l with manifold.

I am quite new myself but as others have mentioned:

• You may be fairly negative when they are full, I use a drysuit and carry a DSMB
• If you use a manifold you need to be able to reach the valves in your back and do a shutdown
  
• The rig is fairly heavy and when they are not on your back they are not easy to move
• I find the twins more stable in water than the single cylinder. The wing wraps around the sides of the tanks and since two tanks takes more space than one the sides of the wing are further apart

 

[Marie13]

I use twins 12l with manifold.

I really like them but as others have mentioned:

• You may be very negative when they are full, I use a drysuit and carry a DSMB
• If you use a manifold you need to be able to reach the valves in your back and do a shutdown
  
• The rig is fairly heavy and when they are not on your back they are not easy to move

That’s why you move them on your back. Safest way. I rarely move mine unless they are on my back.

 

[Skulmoski]

Sidemount with 2 x 7 litre Faber steelies!

 

[AfterDark]

Twin steel tanks with bands and manifold are usually VERY negative in the water, especially when full. I would be very careful about using them with a wetsuit. A BC failure could be end of you. Did you mention whether you're diving wet or dry?

I dive twin AL80s quite a bit, and I can tell you from experience that they are much more work on a boat than any single tank. Doubles are more work in general out of the water. Twin AL80s are fine in the water, maybe about 10lbs negative full (I never really checked, just guessing) and about neutral empty, maybe a bit negative. Steel 100s would be around 25 lbs negative full, I would guess, maybe more.

So to answer your question about which tanks to get, definitely do NOT get twin steels if you are in a wetsuit. Stick with AL80s. Twins are falling out of fashion so I'm sure you could find a good deal on a used set.

Sidemount will likely be your better option if you don't want to fiddle around on land, but believe me, you'll more than make up for that fiddling in the water getting everything adjusted and set.

Neither of these options are nearly as simple and effort-free as just using single tanks. People tolerate carrying doubles or messing with sidemount because they need all that gas and some redundancy. You seem to think that it will be easier or less work to dive with two tanks than it is to simply change tanks. That is not true at all.

I disagree that ID bottles are better than sidemount. you can leave them on while climbing boat ladders with safety clips. for six pack rhibs, unclip in the water, a lot of people doff the bcd when climbing back on a rhib in BM anyways. trying SM a few times is not enough to build proficiency yet, same as trying a drysuit for a few dives will not make you comfortable enough in it yet compared to a wetsuit.

SM costs about the same as the standard BM configuration. you have one extra spg and a left hand valve, but you don't need tank bands. a SM bladder is close to the cost of a doubles wing and the harness is fairly inexpensive if you put one together yourself.

SM is also redundant, easy to handle on land, and they can be used as single tanks too. SM is significantly easier to reach for valve drills or feathering compared to backmount doubles. depending on the valves used, ID can be harder to reach than a doubles manifold.

Nothing posted here is significant enough to changed my mind.

 

[Tribal]

That’s why you move them on your back. Safest way. I rarely move mine unless they are on my back.

I guess the advantage of being taller is you don’t have to do it like that. When I have to take my sets to the LDS I take one in each hand, this way I’m in balance

 

[Marie13]

I guess the advantage of being taller is you don’t have to do it like that. When I have to take my sets to the LDS I take one in each hand, this way I’m in balance

Haha. I don’t have the upper body strength to do that with one set. When going for fills, I use the hand cart DRIS has. The shop by work doesn’t have a cart, but the owner just carries them in and out. Guys universally love my doubles as they are so light to carry (to them). If someone offers to schlep any of my tanks, I take them up on the offer!

 

[Caveeagle]

Did the op ever say exactly where he was diving? Or what conditions?

I did a coupe days of diving near Brisbane last July and was quite surprised by a few things that were different from what I am used to with Florida boat diving.

Tangalooma island was just a short tourist dive. But they had steel tanks, and dove from a neat aluminum pontoon type “landing craft”. Interesting that steel tanks seem to be more common.

On Stradbroke Island, they had aluminum tanks, and we dove from a RIB that was trailers to the beach by a tractor.

perhaps off topic, but I am just pointing out how different diving can be, and maybe the op should clarify how he gets from his car to the dive site.

and, “just because” is a perfectly good reason to learn a new type of diving.

**where the heck are you finding a DPV for the same cost as a set of double tanks? Around here, $3,000 gets you a cheap scooter. I could easily get you three sets of double steel tanks for that. (Or aluminum if you prefer)

 

[runsongas]

Nothing posted here is significant enough to changed my mind.

but not everybody is as implacable and ornery as you