How to locate the optimal height for sidemount cylinder bands

[DevonDiver]

... on the Apeks wsx 25, is the bottom band clip onto the D-ring on waist belt or the dropped Dring where the butt pocket place?

If you mean for deco/stage tanks.. I clip to the rear waist D-ring. I don't use a buttplate at all.

The primary cylinders clip to the front D-ring from the start.

The cylinder attachments cross over and this keeps both tanks very much in trim.

 

[stuartv]

If you mean for deco/stage tanks.. I clip to the rear waist D-ring. I don't use a buttplate at all.

The primary cylinders clip to the front D-ring from the start.

The cylinder attachments cross over and this keeps both tanks very much in trim.

So, you're clipping the deco/stage tank in front of (lower, in horizontal trim) the primary cylinders?

 

[DevonDiver]

So, you're clipping the deco/stage tank in front of (lower, in horizontal trim) the primary cylinders?

Yep. Primaries as normal, with deco/stage snug underneath them.

I've never seen any benefit to putting deco above. Easier to don/doff below, and it makes gas switches clearer.

Similar justification for stages below, plus they're easier to access when passing tight wreck restrictions - those times you may need to jiggle tanks through a space... or have access to remove them simply if it's too snug to pass through with them in place.

Also, on wrecks I'm far more concerned about banging the ceiling... as it can cause collapse and entrapment (and silt out). Easier to get spatial awareness and avoid that when the tanks are in front/below you.

 

[babycover]

Hi Andy,
Thank you. I was of the opinion that my steel tank should clip onto the sliding D-ring on my waist belt with sliding loop bungee and should not clip onto the butt plate D-ring. But lots of people that I talk to, also clip the tank onto their butt plate. So i try to find a way that would be correct and benefit for me in cave diving and deco bottle.
I try your method and located the lower band the same as my distance from my armpit to the waist belt ( 35 inches - my total height is 5"7' ), the steel cylinders seem to hang too low and forward, make my trim head heavy. I then have to clip it on the butt plate which mitigate the problem a bit but still not very trim line and comfortable.

I think the problem might lie where I put my waist belt, some say it quite high, but i think i right on the spot. where would be the correct location for waist belt?

 

[DevonDiver]

There's zero need for a sliding D-ring with steel cylinders. Only aluminium cylinders become positively buoyant when enough gas is consumed, and thus need adjustment in position.

There's 3 factors that work to achieve cylinder trim and position:

#1 - Tank material (steel or aluminium)
#2 - Bungee method
#3 - Cylinder attachment

These 3 factors work best in specific combinations. You can't just mix-and-match incompatible factors and expect success.

 

[Doby45]

So you are saying the measurement below is 35"?? I am 5'11" and that measurement on my system is more like 16". My bands are 16" down from the center of valve knob (I loop my bungee around the valve knob) and my tanks sit perfectly. This is for STEELS that clip to my buttplate..

 

[babycover]

So you are saying the measurement below is 35"?? I am 5'11" and that measurement on my system is more like 16". My bands are 16" down from the center of valve knob (I loop my bungee around the valve knob) and my tanks sit perfectly. This is for STEELS that clip to my buttplate..

View attachment 417987

sorry, was mean to say 35cm so around the same as yours.

 

[Doby45]

sorry, was mean to say 35cm so around the same as yours.

Well thats better, LOL. You may be dealing with issues regarding your leash length. On mine I use zero leash length and my anchor points are 1" back from the centerline.

 

[DevonDiver]

You may be dealing with issues regarding your leash length.

That'd be my thoughts also.

With loop bungees, the cylinder boltsnap leash has to counter the torque created by the bungee. It has to be short for that reason.

How short? As short as feasible, whilst still allowing the snap to move freely. Basically, nearly zero.

With independent or continuous bungees, the cylinders 'hangs' with no torque. So the leash is sized merely to make the tank hang the correct distance down from the attachment point.

 

[babycover]

I see. my leash probably long as i cant fit around 3 fingers to it (the bottom clip). i will shorten and try it to day. will report back
About clip onto the butt plate or the waist belt D-ring, i found it extremely cumbersome after the dive if you clip the cylinders on your buttplate, really hard to get the cylinder off but with the D-ring waist belt, it's very easy