Sidemount Tanks Options

[MyronGanes]

I have a very dense body and use very little weights or none when diving.

Last time I dived in a 7mm wetsuit with an AL80 I used about 8 lbs of weights.

In a drysuit with a Faber steel HP100 and a steel 23 pony I used 3 lbs of weights (total) on my ankles to maintain trim but even then I was overweighted and sank like a rock with an empty BCD and drysuit. It took a lot of air in BCD and drysuit to remain neutral. The pony bottle added to this detriment of course.

What tanks would be my best option to maintain buoyancy optimally in a sidemount configuration? I'd imagine steel tanks would weigh me down A LOT. Should I stick to a pair of AL80's?

 

[tbone1004]

which HP100's were you using? If they were worthington it isn't surprising as they are quite heavy, but if you did proper checks with the AL80, then you should be fine using most steel tanks. The Worthington e series are especially negative, but their LP85's would be my recommendation, especially if you can find someone that will fill them to 3500 psi

 

[DA Aquamaster]

What are you using for a wing?

I use an SMS 50 (a 22 pound wing) for open circuit AL80s with a 5mm wet suit. It will float a pair of AL 80s plus a stage plus reels, back up lights, a can light and 4 pounds of weight.

It works great with a pair of steel 72s with the same items on board on an open circuit dive.

It also works just fine with an AL 72 or AL 80, a KISS Sidekick and a 2L O2 bottle (either a Faber FX15 or an AL 13) for closed circuit diving, however the wing is maxed out when I'm running minimal loop volume.

However the SMS 50 is about 7 pounds short of the buoyancy I need for open circuit with a pair of cave filled Faber LP 85s. Marci however has the same wet suit and the same items of cave diving kit and can float a pair of Faber LP 85s just fine with here SMS 50. The difference is that I'm a lot denser than she is and don't float well in the water even without dive equipment.

For steel tanks larger than a steel 72s, I use a Manta Side mount system (a razor style harness with a 50 pound wing), or I use a drysuit, which adds some positive buoyancy compared to a 5mm wet suit and lets the SMS 50's 22 pound wing perform well with LP 85s, or LP 95s, even with a stage.

You have to consider the tanks, wing and exposure protection as a system.

 

[decompression]

My 2PSI

The steels mentioned are definitely a good way to go but don't necessarily discount Al 80s.

They are a great multipurpose tank that can be trimmed very easily. They are easy to handle, cheap and found everywhere. That's nice because if you travel you'll know how exactly to trim them from your experience. Challenging going from hp 100s to Al 80s if you've never done it.

Unless you're diving cold water consistently where steels would be the better choice, al80s are a good option.

 

[DA Aquamaster]

As noted above AL 80s make good SM tanks, and you will want to know how to trim out with them if you travel.

I really like AL72s as well on smaller dives and their smaller diameter makes them a joy to dive.

With either AL80s or AL72s you can always add a stage for extra gas given the buoyancy traits of those tanks, and that may be a better option that going with a heavier steel tank.

Three AL 80s for example offer 231 cu ft of gas - exactly the same total gas volume as a pair of cave filled LP 85s, but much less negatively buoyant. As noted in my previous post, I can float 3 AL 80s in an SMS 50, and I can't do the same with a pair of cave filled Faber LP 85s.