18L Steel Tank - advice needed

[Angelo Farina]

I am 1.88m (not sure if the 2cm difference is relevant ). I have no doubles or sidemount training and I am not planning to get it until then.

I am basically considering between a 15l or 18l steel tanks but would prefer the latter if feasible.

Doubles do not require any specific training for normal rec diving.
Nor they require a "double wing", your current BP+W is just perfect.
Simply use just one of the two posts for your single reg.
As you already have a backplate, mounting it on the twins is trivial.
You will find them much more streamlined and balanced than a single mono.
I suggest an 8l+8l at 232 bar, plenty of air, light and compact.

 

[David Novo]

You're welcome. Whereabouts are you going to dive? Wherever have fun and good diving!

Red Sea - North Route until the Strait of Tiran.

Doubles do not require any specific training for normal rec diving.
Nor they require a "double wing", your current BP+W is just perfect.
Simply use just one of the two posts for your single reg.
As you already have a backplate, mounting it on the twins is trivial.
You will find them much more streamlined and balanced than a single mono.
I suggest an 8l+8l at 232 bar, plenty of air, light and compact.

Just twin 12L are available for rental.
Will a 13L singles wind fully expand with twins?
I was under the impression that it may take some time to get used to dive with doubles. Is that not the case?

 

[Angelo Farina]

Red Sea - North Route until the Strait of Tiran.



Just twin 12L are available for rental.
Will a 13L singles wind fully expand with twins?
I was under the impression that it may take some time to get used to dive with doubles. Is that not the case?

I mean compact twins. Not two 15 liters...
Years ago the usage of 10l+10l twins was more common than singles, and they were used for initial training of new divers, thanks to the better balance and trim you get with them.
Singles became common only when they were made much smaller (11 liters), as typically employed in PADI courses.
But this provides too small amount of air for certain diving profiles.
Now that the standard pressure has increased almost everywhere from 200 bar to 232 bar, a 10l+10l is considered too bulky, and the optimal size for twins reduced to something as 8.5l+8.5l. At 232 bars, this still means 3940 liters, almost the same as the old 10l+10l at 200 bars (4000 liters). A 18 liters single at 232 bars is 4176 liters total, but I do not think that the additional amount of air is worth the bulky size and weight, and the resulting bad trim and great drag resistance...
As others already suggested, I also suggest a compact twin instead of a bulky single.

 

[David Novo]

I mean compact twins. Not two 15 liters...
Years ago the usage of 10l+10l twins was more common than singles, and they were used for initial training of new divers, thanks to the better balance and trim you get with them.
Singles became common only when they were made much smaller (11 liters), as typically employed in PADI courses.
But this provides too small amount of air for certain diving profiles.
Now that the standard pressure has increased almost everywhere from 200 bar to 232 bar, a 10l+10l is considered too bulky, and the optimal size for twins reduced to something as 8.5l+8.5l. At 232 bars, this still means 3940 liters, almost the same as the old 10l+10l at 200 bars (4000 liters). A 18 liters single at 232 bars is 4176 liters total, but I do not think that the additional amount of air is worth the bulky size and weight, and the resulting bad trim and great drag resistance...
As others already suggested, I also suggest a compact twin instead of a bulky single.

Thanks for your post.
However, everywhere I dove, rentals seem to be filled to 200 bar, not 230...
My questions still stand though:

Just twin 12L are available for rental.
Will a 13L singles wind fully expand with twins?
I was under the impression that it may take some time to get used to dive with doubles. Is that not the case?

 

[jaseUK666]

Red Sea - North Route until the Strait of Tiran.



Just twin 12L are available for rental.
Will a 13L singles wind fully expand with twins?
I was under the impression that it may take some time to get used to dive with doubles. Is that not the case?

For twin 12s, you'd need a twin-set wing with at least 20 kgs if lift. A single wing would be too narrow and wouldn't inflate fully.

Diving with twins isn't that different. It's a lot more weight, you're substantially more negatively bouyant at the start of the dive because of the extra gas, but your going to have these issues with one very large tank. The twins would also be better balanced on your back.

 

[David Novo]

For twin 12s, you'd need a twin-set wing with at least 20 kgs if lift. A single wing would be too narrow and wouldn't inflate fully.

Diving with twins isn't that different. It's a lot more weight, you're substantially more negatively bouyant at the start of the dive because of the extra gas, but your going to have these issues with one very large tank. The twins would also be better balanced on your back.

That was my understanding but was a bit confused with one of the posts above. Thanks.

 

[runsongas]

Yes.
And the length of a 149 cuft HP tank is a mere .2" longer than that of a 120 cuft HP tank (29.53" vs. 29.33")

The 3442 psi faber is 28 inches without the valve iirc, unless you are referring to the old 3180 psi 3AA tank?

 

[Angelo Farina]

Thanks for your post.
However, everywhere I dove, rentals seem to be filled to 200 bar, not 230...
My questions still stand though:

I see , you have only access to 200 bars filling and 12+12 liters twins, which indeed are bulky and heavy.
They give you 4800 liters, which is really a lot. I never dove with such a large tank, so I cannot be of real advice.
I like twins more than a single , you are more balanced and have less drag, but the largest ones I used were 10+10 liters steel or 9+9 liters aluminium.
Regarding your wing, it really depend how it is shaped and how your backpack protrudes from the twins.
My setup uses a plastic frame, not an aluminium or steel plate, and is quite thick. When mounted on twins, there is enough space for the bladder to fill completely. My bladder is not a donut, indeed, it is a modular system manufactured by Coltri only for instructors 30 years ago, and no more in production since many years.
"modern" donut wings are probably better suited for a single tank, while my one was born for 10+10 liters twins, albeit it works great also for a single 15-liters.
I also used a 16 liters 250 bars steel single, which is substantially as compact as the 15 liters, but it is much heavier. It gives you the same 4000 liters as a 10+10 liters twin, but also this is not a good option for you, if you can only fill at 200 bars.
As you are tall, and hopefully robust, probably you can go well with the 18-liters single. I am not so tall (just 1,75 m) and definitely not robust (just fat), hence I could not even consider it.
But we are not all equal, everyone should find the proper setup for him. Hence the advise you receive here should always be evaluated with some discerning, and adapted to your specific case.

 

[David Novo]

I see , you have only access to 200 bars filling and 12+12 liters twins, which indeed are bulky and heavy.
They give you 4800 liters, which is really a lot. I never dove with such a large tank, so I cannot be of real advice.
I like twins more than a single , you are more balanced and have less drag, but the largest ones I used were 10+10 liters steel or 9+9 liters aluminium.
Regarding your wing, it really depend how it is shaped and how your backpack protrudes from the twins.
My setup uses a plastic frame, not an aluminium or steel plate, and is quite thick. When mounted on twins, there is enough space for the bladder to fill completely. My bladder is not a donut, indeed, it is a modular system manufactured by Coltri only for instructors 30 years ago, and no more in production since many years.
"modern" donut wings are probably better suited for a single tank, while my one was born for 10+10 liters twins, albeit it works great also for a single 15-liters.
I also used a 16 liters 250 bars steel single, which is substantially as compact as the 15 liters, but it is much heavier. It gives you the same 4000 liters as a 10+10 liters twin, but also this is not a good option for you, if you can only fill at 200 bars.
As you are tall, and hopefully robust, probably you can go well with the 18-liters single. I am not so tall (just 1,75 m) and definitely not robust (just fat), hence I could not even consider it.
But we are not all equal, everyone should find the proper setup for him. Hence the advise you receive here should always be evaluated with some discerning, and adapted to your specific case.

Tall yes (at least for the standard 6' that everyone states for these tanks), robust not really but I am sure I can carry it on a LOB from the bench to the water and back

 

[Schwob]

The 3442 psi faber is 28 inches without the valve iirc, unless you are referring to the old 3180 psi 3AA tank?

@runsongas
Honestly, I have no idea what the then fairly new Faber HP120 tanks were that I played with some 3 ... 3.5 years ago. I went by the table leisure-pro links to on this page
Faber High Pressure Steel Tank
(blue link spelling “see size chart”))
IDK how to link to the table directly) and picked the HP120 and the HP149 dimensions from that table. I possibly may be incorrect in assuming they’d reference current data. There an HP120 is 29.33” long and an HP149 is 29.53”” long. I never measured either one personally. I, after some Faber HP120 playtime then concluded for myself that I would not mind trying an HP149 if given the chance. I deem it very Dive able for me. But I also concluded it is too long for me to carry comfortably. I’d need a dolly or I’d need to cradle it (as I’d do with doubles if not on a dolly or on my back).
So, if you know what length the then 1/2 year old Faber tanks were I borrowed 3 years ago, and if the data leisur-pro links to is not correct (or of another vintage), .... fine! I truly would not know. I do know I found them quite long at yet they were wonderfully dive-able to me.