Attaching Twin 12 Carbondive 300bar cylinders to Mares Magellan BCD

[CaymanLeisureDiver]

Hello, I would be most grateful for people's advice, please.

Background. I am a reasonably experienced diver, with 400 dives since 2002, in a range of countries and conditions including as a BSAC Advanced Diver and Advanced Instructor on military expeditions, when I was in the British Army. I am now living my best life in the Cayman Islands, and my days of cold dark English quarries, drysuits, strong currents, low visibility, no clear surface dives, expedition planning and RHIB piloting are behind me! Over here in Cayman, I go shore diving every weekend from a variety of locations, occasionally lionfish hunting, having attended the obligatory course, paid my fee and got my licence.

Question. I have a Mares Magellan BCD, which is superbly lightweight and convenient. I would however like to extend my dive time, particularly when lionfish hunting, so I intend to purchase a Twin 12 liter carbon tank Carbondive 300bar. How can I attach this to my BCD, or do I need to consider replacing the BCD either with a more technical one or with a wing?

Comments. All other factors being equal, I would prefer to continue using my current BCD. because (a) I like it; (b) I don't want to accumulate tons of dive kit; and (c) if I returning to instructing, BCDs are obviously better for demonstrating to students.

Many thanks in advance for any advice anyone can offer!

Current BCD and intended new cylinder purchase (links above):

 

[happy-diver]

Yeah man but where are you going to bolt the extra 400 kilos of weight you will need

 

[Scared Silly]

Welcome to SB. The Mares Magellan BCD is totally inappropriate for diving a twinset. In fact, twinset can not even be attached to it. As for the cylinders, as said above you are gonna need a lot of lead to sink.

My suggestion, look at a set of AL80s. For open warm water they are the twinset you want to dive. The look at a backplate system. Finally, if you don't want to accumulate tons of dive kit, you need to rethink your priorities .

 

[GDHLEWIS]

You will need a new BC for twin sets. doubles BPW will be needed and can be found for a reasonable price.

 

[Edward3c]

Hello, I would be most grateful for people's advice, please.

Background. I am a reasonably experienced diver, with 400 dives since 2002, in a range of countries and conditions including as a BSAC Advanced Diver and Advanced Instructor on military expeditions, when I was in the British Army. I am now living my best life in the Cayman Islands, and my days of cold dark English quarries, drysuits, strong currents, low visibility, no clear surface dives, expedition planning and RHIB piloting are behind me! Over here in Cayman, I go shore diving every weekend from a variety of locations, occasionally lionfish hunting, having attended the obligatory course, paid my fee and got my licence.

Question. I have a Mares Magellan BCD, which is superbly lightweight and convenient. I would however like to extend my dive time, particularly when lionfish hunting, so I intend to purchase a Twin 12 liter carbon tank Carbondive 300bar. How can I attach this to my BCD, or do I need to consider replacing the BCD either with a more technical one or with a wing?

Comments. All other factors being equal, I would prefer to continue using my current BCD. because (a) I like it; (b) I don't want to accumulate tons of dive kit; and (c) if I returning to instructing, BCDs are obviously better for demonstrating to students.

Many thanks in advance for any advice anyone can offer!

Current BCD and intended new cylinder purchase (links above):
View attachment 840924View attachment 840925View attachment 840926

I’m disappointed to see a BSAC AD/AI asking such a question. This is the sort of question less experienced BSAC divers would ask you and expect you to know the answer. To get your AD you should has demonstrated knowledge of multiple kit and cylinder configurations.

Be that as it may, can you get the proposed cylinders filled and tested. They need more looking after than steel or aluminium, plus the extra lead required has made them impractical for most diving situations. Just buy an appropriate BCD/Wing, you can use the shop’s equipment if you get back into teaching.

 

[lowwall]

You have a single tank BCD. If you want to stick with it and carry more gas, then get a larger single tank. An HP120 or HP133 (15L or 17L) will be less hassle and much lower cost than your proposed €1690 twin-set.

If you want redundancy as well, then add a pony bottle.

 

[happy-diver]

Now I've got a few of this style that work adequately with manifolded twins

I use them with bands with a bridge

Ebay cheep, ish!

 

[Angelo Farina]

I went through the path of twin tanks, and finally I did set on a 15 liters steel with dual valve, which still provides a reasonable amount of redundancy, and requires very little weight in your belt.
A 232-bars tank requires 5kg.
A 250 bars tank requires just 2 kg .
I never used a 15-liters 300 bars tank, but I suppose it requires no weights.
Faber 15 liter tanks are perfect for a plate-less BCD as your ons, or as my wife's Cressi, which is quire similar.
Of course a twin tank contains more air, but a 15 liters at 250 bars still exceeds the needs for any recreational dive even deep and with deco.

 

[Alastor]

Ciao Angelo, I believe the OP will need many more kilos in the belt: he's speaking about carbondive 12L (steel+carbonfiber) tanks and they weight just 10.9 Kg each. Much less of 12L steel tanks we are used to. When almost empty, he need to balance the tank (that should be positive) and the used gas (if he had "only" 50 bars in the set, he'd been used 250bars that is 6000l - aproximately 7.8 Kg.)

 

[Angelo Farina]

Ciao Angelo, I believe the OP will need many more kilos in the belt: he's speaking about carbondive 12L (steel+carbonfiber) tanks and they weight just 10.9 Kg each. Much less of 12L steel tanks we are used. When almost empty, he need to balance the tank (that should be positive) and the used gas (if he had "only" 50 bars in the set, he'd been used 250bars that is 6000l - aproximately 7.8 Kg.)

I fully understand how carbon-fiber tanks are really bad for scuba diving, being too light.
But my point is: 24 liters x 300 bars = 6800 liters !!!
Who needs such a massive amount of gas, in a twin tank?
I can understand using multiple tanks with different gas mixtures for doing very deep (tech) deco dives, but for "normal dives" in air, that amount of gas ins insane.
A 15 liters, 250 bars steel single tank contains 3750 liters, which, in my experience, are plenty enough even for deep dives with some deco. So I would like to understand where the need from such a massive amount of gas comes from...