Double 80s work fine in an open water environment but can be a bit lacking in a cave environment.
Whether double AL80s are enough depends to a large extent on where you dive and who you dive with. In Mexico where caves tend to be shallower, they will work fine. However in Florida where caves on average tend to run deeper (60-110') they will not be as satisfactory.
That is expecially true if your team mates all have larger tanks. LP 95's are common and most of the time they are cave filled to hold 130 cu ft. 1/6th of 260 cu ft is 43 cu ft while 1/6th of 154 cu ft is only 26 cu ft. The reality is that double 80s will not make you very popular as a team mate, expecially with divers who have been through that first few hundred feet of cave several times - and you will soon find yourself severely limited as well.
I'd regard double 100s as the absolute minimum and LP 95s or HP 130s are preferrable.
It is true you can use 7.25" bands on larger tanks, but that diameter limits your options to HP 100s, like the X7-100, and X7-120. But the X7-120 is too long to trim well for most people under 6 ft tall. So in the end, an investment in 7.25" bands is largely wasted.
In terms of cost, it is not uncommon to find a set of suitable used steel doubles here or on the Deco Stop or Cave Divers Forum in the $500 range. In the big picture, that is only $200-$250 more than you will probably spend doubling a set of AL80s and you will be much more satisfied with them.
The suggestion that you could use AL 80s as independent doubles is also true, but it will severely limit your choice of instructors and many would not agree with a student using that configuration. If you are going the independent doubles route, you would be better off with a sidemount configuration (which will also limit instructor choice as well as certification agency choices) but again you still have the 26 cu ft limit to deal with.
Turning the left tank around to get by with a standard right hand valve will leave the left reg dangerously exposed and is a bad idea in a cave environment. Again, you'd be better off sidemount if you planned to do that.
Whether double AL80s are enough depends to a large extent on where you dive and who you dive with. In Mexico where caves tend to be shallower, they will work fine. However in Florida where caves on average tend to run deeper (60-110') they will not be as satisfactory.
That is expecially true if your team mates all have larger tanks. LP 95's are common and most of the time they are cave filled to hold 130 cu ft. 1/6th of 260 cu ft is 43 cu ft while 1/6th of 154 cu ft is only 26 cu ft. The reality is that double 80s will not make you very popular as a team mate, expecially with divers who have been through that first few hundred feet of cave several times - and you will soon find yourself severely limited as well.
I'd regard double 100s as the absolute minimum and LP 95s or HP 130s are preferrable.
It is true you can use 7.25" bands on larger tanks, but that diameter limits your options to HP 100s, like the X7-100, and X7-120. But the X7-120 is too long to trim well for most people under 6 ft tall. So in the end, an investment in 7.25" bands is largely wasted.
In terms of cost, it is not uncommon to find a set of suitable used steel doubles here or on the Deco Stop or Cave Divers Forum in the $500 range. In the big picture, that is only $200-$250 more than you will probably spend doubling a set of AL80s and you will be much more satisfied with them.
The suggestion that you could use AL 80s as independent doubles is also true, but it will severely limit your choice of instructors and many would not agree with a student using that configuration. If you are going the independent doubles route, you would be better off with a sidemount configuration (which will also limit instructor choice as well as certification agency choices) but again you still have the 26 cu ft limit to deal with.
Turning the left tank around to get by with a standard right hand valve will leave the left reg dangerously exposed and is a bad idea in a cave environment. Again, you'd be better off sidemount if you planned to do that.
