Twin Tanks

[packeteer]

I find double 12's easier/more comfortable to swim in than a large single (steel) tank. Part of it has to do with the tanks themselves; the tanks are thinner and closer to your back and don't pull you over as much when tilt.

I've been debating doubling my 12's or buying an 18L tank. Thanks for the input

 

[ajduplessis]

I've been debating doubling my 12's or buying an 18L tank. Thanks for the input

I assume the 12’s you have are the tall ones? The compact “bomb” size 12 does not work well (even thou the diameter is the same as the 15's) as most of the weight will be on your shoulders.

Tanks size is all dependent on your diving requirements. 12 & 15l steel tanks are generally the norm, or at least here. I have 15's and work really well and they fulfil my current needs. I have dived with 18's and would not recommend then unless you really require that amount of gas.

 

[Grant R]

Thanks for the advice.

I'm thinking about getting a new BC that can handle twins, and the shop owner was very strongly in favor of "no less than 60" and "more is better". I told him how and where I dive.

I've always got mixed opinions about the way I should approach diving. And I am very open minded. I'm a perpetual student. I have shaped my diving to my own diving environment, which is not everyone's cup of tea.

Its clear that the questions I'm asking about twins are the same. I wear an integrated weight system with 40lbs lead and 60lbs lift. My drysuit probably adds 15lb of lift. I once put on an additional weight belt, adding 20lbs, and got into a stiff tide change and emptied my BC. and dropped firmly to the bottom, I noticed my buddy was gone, went back 30 feet and found him holding onto a rock and waving in the current like a flag in the wind. I grabbed him, pulled him down, emptied his BC and we got out safely without exertion. The pickup boat had a hard time in the current. It was not fun at the end, but we were also loaded with an overstuffed goody bag of Sea Cucumbers.

I like having two separate weight systems, since I could dump 20lbs and rise more slowly. I've done one emergency ascent in my life when I was young. I was wearing a drysuit, and launched like the space shuttle from 40 feet, hitting the surface like a pillsbury doe boy in reverse-parachuter sprawl. I had been sharing my air trying to get another diver back to the surface from 90 feet, and wow, the air consumption was massive. One more reason I'm liking twins. Only if I'm deliberatedly going into a place where the tide change is likely to present a real challenge would I carry 60lbs of weight. It can be very easily managed this way. Dumping that much weight is a hazard, but getting yanked off into oblivion is something I've observed. I was diving at Keystone and a new diver ventured to the end of the jetty and got pulled out into the ferry lanes. The Captain on the ferry waved at him as he drifted buy. I avoided the end of the jetty since I was with another newer diver.

I'd like to know whether I should even think about going to these favorite spots with twins. It may be too much drag. I'd love a DPV, but "ideal" has a price tag. So about the BC's, What is a favorite BC that can manage twins well? What about fin preferences? Always the learner...

 

[packeteer]

I assume the 12’s you have are the tall ones? The compact “bomb” size 12 does not work well (even thou the diameter is the same as the 15's) as most of the weight will be on your shoulders.

Tanks size is all dependent on your diving requirements. 12 & 15l steel tanks are generally the norm, or at least here. I have 15's and work really well and they fulfil my current needs. I have dived with 18's and would not recommend then unless you really require that amount of gas.

Yes, I have the tall ones (2 x 12.2L Fabers). Unfortunately, I'm a real air pig. So I've been looking at tank options.

hmm, unless my math is wrong, a 15L should hold approx 500 more litres of gas. At my 'normal' usage, that should get me an extra 5 minutes on an average dive.

 

[String]

A twinset is not a solution to high gas usage

 

[Grant R]

Anyone taking offence at anything in my posts - tough. It's only an internet forum. Stop being over-sensitive. The real world isn't as warm and fuzzy.
Remember, underwater only YOU are responsible for YOUR own safety. Nobody else is.Well, said.

I'd rather have someone be brutally honest that warm and fuzzy. I'm here to learn and share, "as Iron shapens Iron".

 

[Grant R]

Can you help me understand the benefits of the 94# wing. Who makes your BC? I'd think the

With regard to an earlier question "six inches of movement per kick?" I was testing how fast I could go, and was trying to sprint back very fast and very innefficiently" I use to have Large Jetfins, which were much more powerful. I replaced them with thinner plastic fins that are not as powerful, and the twin really made that more obvious.

 

[evil_xander]

Can you help me understand the benefits of the 94# wing. Who makes your BC? .

Honestly? The only benefit is if you plan to lift things from the bottom with it.

I dive a 30 lbs wing for a single tank (and a drysuit) or a 45 lbs for my small doubles (2x12), which can handle without any problems 2x AL11 stages (those would be AL80s if I'm correct).

Cannot comment on the conditions on your dive locations, but 94 seems rather useless for anything.

 

[kanonfodr]

Thanks for the advice.

I'm thinking about getting a new BC that can handle twins, and the shop owner was very strongly in favor of "no less than 60" and "more is better". I told him how and where I dive.

I doubt it. If you need that much lift your rig isn't balanced. You might want to watch this: YouTube - GUE Balanced Rig and see what it says. I'm going to address the in a bit, since you have some inter-related issues here.

I've always got mixed opinions about the way I should approach diving. And I am very open minded. I'm a perpetual student. I have shaped my diving to my own diving environment, which is not everyone's cup of tea.

Congratulations! But there are still lots of tenets of safe diving that apply to all types of diving: blue-water reef diving, deep cave/wreck diving, and hunting down dinner in places struck by awe-inspiring currents.

Its clear that the questions I'm asking about twins are the same. I wear an integrated weight system with 40lbs lead and 60lbs lift. My drysuit probably adds 15lb of lift. I once put on an additional weight belt, adding 20lbs, and got into a stiff tide change and emptied my BC. and dropped firmly to the bottom, I noticed my buddy was gone, went back 30 feet and found him holding onto a rock and waving in the current like a flag in the wind. I grabbed him, pulled him down, emptied his BC and we got out safely without exertion. The pickup boat had a hard time in the current. It was not fun at the end, but we were also loaded with an overstuffed goody bag of Sea Cucumbers.

Wow, I'm assuming this is using a single-tank rig in a wetsuit? And you're adding an add'l 20 lbs of lead (for a total of 60) when you use a drysuit? WOW!!! I'd give up diving if I had to slog that weight for every dive, and this is coming from a guy who's job makes him do long walks with lots of heavy gear in "interesting" places. I can understand carrying a bit of extra weight to help you stay down on dives where you are mucking around on the bottom, but have you done a proper weight check to determine what you're needs are for proper weighting, then you would just add weight to cover the loss of negative bouyancy due to depleting your tanks? I would venture you could possibly shed a lot of land weight, make your diving better, and you would last longer on a single tank so you'd get more dinner.

I like having two separate weight systems, since I could dump 20lbs and rise more slowly. I've done one emergency ascent in my life when I was young. I was wearing a drysuit, and launched like the space shuttle from 40 feet, hitting the surface like a pillsbury doe boy in reverse-parachuter sprawl. I had been sharing my air trying to get another diver back to the surface from 90 feet, and wow, the air consumption was massive. One more reason I'm liking twins. Only if I'm deliberatedly going into a place where the tide change is likely to present a real challenge would I carry 60lbs of weight. It can be very easily managed this way. Dumping that much weight is a hazard, but getting yanked off into oblivion is something I've observed. I was diving at Keystone and a new diver ventured to the end of the jetty and got pulled out into the ferry lanes. The Captain on the ferry waved at him as he drifted buy. I avoided the end of the jetty since I was with another newer diver.

I'd like to know whether I should even think about going to these favorite spots with twins. It may be too much drag. I'd love a DPV, but "ideal" has a price tag. So about the BC's, What is a favorite BC that can manage twins well? What about fin preferences? Always the learner...

Well, the recommended choice for doubles in a backplate/wing setup, but it works incredibly well for singles and if you use a steel plate then you could drop 6 or more pounds from your weight belts and it oftentimes results in an overall lighter rig since it doesn't feature a lot of the bouyant padding of other types of BCs. As far as fins, any stiff, broad-bladed fin should do fine. Many divers like the Scubapro Jets, OMS Slipstreams, and Hollis F1s. Especially in a drysuit, I like the negative tendencies of the Jets and F1s as they help keep my feet down.

But I really think your configuration could use lots of optimization, and I don't understand why the shop owner you are referring to is suggesting such overly large amounts of BC lift, but I hope you will try some of these solutions. I'm even more hopeful that they work

Peace,
Greg

 

[Grant R]

Thanks for taking the time to respond on all these points. Its very helpful, and why Scubaboard is such a great place to come to.