Tiny Doubles Gas Capacity

[Lopez116]

I live on a small island in the Caribbean, so getting stuff here is difficult. I want to make sure I get it right.

I'm thinking of building a set of tiny doubles (Faber 50s) as I dive solo most of the time and want some redundancy and additional gas. I mainly do photography, so my diving is usually a max depth of 75' or so.

Debating between diving these 50's or double AL 80s. At first glance, I'm thinking 100 cf of gas vs 80 cf isn't a big difference and maybe not worth it. But, I'm also reading people getting 120+ cf if they overfill them. Is overfilling common? My local shop regularly fills their AL80s to 3200-3400. Not sure what they'd fill the 50's to.

 

[formernuke]

I can tell you double 50's trim out wonderfully in the water. I prefer them even at regular fill pressure to single 100 just for comfort reasons.

 

[tursiops]

My local shop regularly fills their AL80s to 3200-3400.

Makes me nervous....
You can greatly overfill the steel 50s, but beware of the AL any size.

 

[ermaclob]

I live on a small island in the Caribbean, so getting stuff here is difficult. I want to make sure I get it right.

I'm thinking of building a set of tiny doubles (Faber 50s) as I dive solo most of the time and want some redundancy and additional gas. I mainly do photography, so my diving is usually a max depth of 75' or so.

Debating between diving these 50's or double AL 80s. At first glance, I'm thinking 100 cf of gas vs 80 cf isn't a big difference and maybe not worth it. But, I'm also reading people getting 120+ cf if they overfill them. Is overfilling common? My local shop regularly fills their AL80s to 3200-3400. Not sure what they'd fill the 50's to.

I'm confused with what you mentioned, twin 50s have 100cuft total AL80s have ~160 cuft total (not 80). A 60 cubic feet is substantial difference, that's a whole aluminum 63 extra on your back.

If your just going recreational diving the twin 50s should be good. I don't think they have enough volume for any deco dives at least not with a reasonable gas plan. I personally have a set of double 63s I used to dive a while ago. plenty of gas for 2 good dives as long as you have decent air consumption. the 50s are probably better for trim and overall fell also. The down side to them is that building them might be a little more pricy/ hard as the bands are not as common and the steel tanks are more expensive depending on where you get them.

Aluminum 80s are great especially for warm water, but they exist at least for me in a middle ground between to big and to small.....particularly out of water where they weigh like 65 pounds. From what I can tell the Faber 50s banded should be about 45LBs if beach diving is your thing I would also say the 50s are the ones you want.

 

[Lopez116]

I'm confused with what you mentioned, twin 50s have 100cuft total AL80s have ~160 cuft total (not 80). A 60 cubic feet is substantial difference, that's a whole aluminum 63 extra on your back.

If your just going recreational diving the twin 50s should be good. I don't think they have enough volume for any deco dives at least not with a reasonable gas plan. I personally have a set of double 63s I used to dive a while ago. plenty of gas for 2 good dives as long as you have decent air consumption. the 50s are probably better for trim and overall fell also. The down side to them is that building them might be a little more pricy/ hard as the bands are not as common and the steel tanks are more expensive depending on where you get them.

Aluminum 80s are great especially for warm water, but they exist at least for me in a middle ground between to big and to small.....particularly out of water where they weigh like 65 pounds. From what I can tell the Faber 50s banded should be about 45LBs if beach diving is your thing I would also say the 50s are the ones you want.

Sorry, good point. I should have clarified. I want to make sure putting together this set of double 50's will actually be worth the difference vs diving a single AL80 (which is what I almost-always dive; I also dive CCR, but don't like to do it alone). The twin 50's will, of course, give me redundancy, but I like the idea of also getting some more gas if I'm spending the money to put together this set.

 

[formernuke]

Sorry, good point. I should have clarified. I want to make sure putting together this set of double 50's will actually be worth the difference vs diving a single AL80 (

For me how much more comfortable they are in the water alone was worth it and before I was diving a single 100.

 

[Gone for diving]

I love lp50s,, but it's more for 1 long dive, not normal enough for a second dive,
Double 80s will give you tons for 2+ dives,,

 

[MichaelMc]

I have tiny 50s and tiny 40s and definitely like the extra gas from the 50s even without over fills. The 50s are negative, so make sure you plan for that. I mostly sidemount mine, but had back mounted each, which is very nice.

 

[ermaclob]

Sorry, good point. I should have clarified. I want to make sure putting together this set of double 50's will actually be worth the difference vs diving a single AL80 (which is what I almost-always dive; I also dive CCR, but don't like to do it alone). The twin 50's will, of course, give me redundancy, but I like the idea of also getting some more gas if I'm spending the money to put together this set.

ok, it really depends on the dives your want to pull of with the twin set. As someone else mentioned above they would work best for one long dive. I'm sure you can do 2 dives with them granted the deeps aren't to deep. I've seen plenty of people on dive boats use a single 100 for a 60ft dive and then a shallow reef at ~30 to 20 ft. and get reasonably good bottom times.

Cost wise its a different story, getting your hands on single AL80s is pretty easy and relatively inexpensive especially if you get them used. the double 50s will be notably more pricey new or used, plus all the extra hardware. that being said if you are planning on doing solo dives weather truly alone or even with "same ocean buddies" I would consider a set of doubles.

Question, have you looked at some of your past dives you've done on open circuit and tried to calculate if the twin 50s would be a god choice as far as having enough gas is concerned?

Another thing I would consider looking at is weather your dive shop would knows how to fill and certify low pressure steels, I've had the problem here where I live that the dives shops don't understand the 2400 + rating. Not knowing how to hydro the tank for it as well as thinking that 2400 is the max pressure with the + sign (Should be 2640 psi). IF they do at least know this, then I would also ask the person that normally fills the tanks for you at the fill station if he's ok with putting a bit more air in them. This is however normally not a common practice out side of cave diving communities so you might get looked at funny by the shop guy and get an out right NO. if they are ok with it then you got your self a pretty good situation to be diving the twin 50s. Make sure to stack the burst disks on the tanks if you do intend to over fill them though, a real "cave fill" as they're called can be up words of 4000 psi some times.

 

[tbone1004]

I live on a small island in the Caribbean, so getting stuff here is difficult. I want to make sure I get it right.

I'm thinking of building a set of tiny doubles (Faber 50s) as I dive solo most of the time and want some redundancy and additional gas. I mainly do photography, so my diving is usually a max depth of 75' or so.

Debating between diving these 50's or double AL 80s. At first glance, I'm thinking 100 cf of gas vs 80 cf isn't a big difference and maybe not worth it. But, I'm also reading people getting 120+ cf if they overfill them. Is overfilling common? My local shop regularly fills their AL80s to 3200-3400. Not sure what they'd fill the 50's to.

small island on the caribbean I would use aluminum bottles to not have to worry about rust. The 50's are undoubtedly better if and only if you can get 3600psi fills on them, but if I was in the caribbean I would prioritize aluminum bottles.