Side mount starting point ?

[oldschoolto]

Okay, My twin 40's are ready for mounting to my BC.. I'm thinking I should put the tanks on a angle iron to find the balance point of the tank and then move the mounting clamp up a little bit to get the tank to sit level in the water.. The bottom strap just holds the tank into the body... Then adjust the webbing to get the tank sitting were I want it under my arm.. ? This should give me a good starting point that should be ball park....

Jim...

 

[tbone1004]

the tanks center of buoyancy changes as they are breathed down

 

[oldschoolto]

the tanks center of buoyancy changes as they are breathed down

Yes... Understand that... I could set up the tank in the bathtub... My wife lives in Houston, Tx as the nanny for my grand kids.. So I am free to do silly stuff like that..

I would think that if I filled one tank to 3000 psi and the other to 500 psi then split the different with the neck on the lighter side to stop the bottom of the tank floating up like I see in so many photo's of side mount divers

jim...

 

[oldschoolto]

I'm looking for this..

Not this...

Jim....

 

[northernone]

I've been unsuccessful myself in finding a sweetspot in strap position that eliminated the need for adjusting the mounting point on the webbing mid dive with al80. I like the sound of your idea but I am not confident the dynamics of a tank will allow it to help you much. The heavy valve and regs are the constant I can't compensate balance for without adding lead. (unpopular but effective solution)

If I'm understanding right you'd want the entire tank up float up while remaining parallel to your body? Pivoting slightly on the strap but not significantly.

 

[Coztick]

Any aluminum cylinder will get positive at some point.
By using a second set of d rings and short bottom leashes, you can attach closer to the front of the harness thus holding the cylinders in trim.
Aluminum cylinders hang until they float.
You may also add weight to the cyl's instead but is less streamlined.

 

[RainPilot]

It’s more important to consider the armpit to waist length for you irrespective of tanks. My SM rigging is set up valve to bottom leash the same distance regardless of tank length.

The main variable once you have that is leash length which will allow a certain amount of movement and where on the waist they are attached. I use weightbelt buckles with D rings welded on to allow me to slide the hip attachment where I need it.

 

[oldschoolto]

Well the tank is neg -0.7lbs full and pos +2.4 empty... So I need to find the positive at 500psi ... That'll give me my swing number.. adding a little weight to the bottom mount of the tank makes some sense in that I'll need the weight to off set the about 4 lbs positive at the end of the dive... it's on your belt or the tank.. Why not make the tank more neutral ? I'm looking forward to playing with this..

And It's not just a side mount rig.. Back mounted 80cu and then the 40's side mounted.. Lots of gas for deep lionfish hunting in Bonaire..

Jim...

 

[DevonDiver]

I'm looking for this..
View attachment 418223

@Sevenrider860 he's looking for you

 

[Coztick]

And It's not just a side mount rig.. Back mounted 80cu and then the 40's side mounted.

So, the same amount of gas as twin 80s with all the discomfort of backmount?
Lol, my rig can too but never will.
But don't let me or anyone else tell you right from wrong. Mostly it's just personal preference as long as it's safe. ie; enough lift etc.
Just try some larger cyl.s to compare.
Cheers