Balanced Rig Newbie Question

[JustinRyan]

I just set up my first BP/W and I wanted to ensure that I’ve done the balanced Rig Calc correctly. I’m currently self studying for either a GUE or UTD fundies/essentials class (both seem awesome) and I wanted to get my gear squared away before I sign up for the class. Do these calculations look reasonable?

For the Wetsuit buoyancy estimations I used ~1/4 surface buoyancy and the general rule of 3# of lift per mm of neoprene for surface buoyancy.

BP/W config: DGX SS BP, SS STA w/2 SS Cams, OxyCheq 30#

I haven’t tried this setup yet, but I plan on testing it in the pool this weekend.

Thanks in advance for the advice.

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[TSandM]

Looks good to me. It's amazing what thick wetsuits can lose as far as lift goes.

 

[OtherHalf]

I'm assuming you're using the Catalina S80 and not the C80? I'm tracking weight for that cylinder at -1.8 at 3000psi and +4.0 at 0psi. Nothing major. Are your weights estimates or confirmed?

I'm about to do the same thing with my gear once I get my new BP rigged up. Time to try and balance out the doubles for me. I like your excel method, I'll probably steal your system.

 

[JustinRyan]

I'm assuming you're using the Catalina S80 and not the C80? I'm tracking weight for that cylinder at -1.8 at 3000psi and +4.0 at 0psi. Nothing major. Are your weights estimates or confirmed?

I'm about to do the same thing with my gear once I get my new BP rigged up. Time to try and balance out the doubles for me. I like your excel method, I'll probably steal your system.

I pulled those cylinder numbers off of XS scuba's website. I just did a Google search and found a cylinder weight table at huronscuba.com with the same weight profile that you posted. Looks like I need to make a small adjustment for that.

The weights are estimates based on manufacture specs. I could use a spring scale in a pool, but I figure the error small enough to not make much of a difference.

If you would like the excel worksheet, I would be happy to email it to you.

 

[eelnoraa]

The table looks good. If you can swim up 5.6lb, you have a balance rig. However, there is one catch. In case of total wing failure, you ditch 15lb belt. Sure you can swim up -5.6lb at 100ft, but as your ascent, you wetsuit expand again. Maybe by the time you reach 50ft, you will be come positive and you will have uncontrolled ascent at that point. You may want to reduce your ditchable weight a bit.

 

[JustinRyan]

Looks good to me. It's amazing what thick wetsuits can lose as far as lift goes.

Pretty crazy that it goes from about 22#'s to 6#'s in 100' (assuming that my estimates are correct). I'm really considering diving dry and eliminating that variable buoyancy of the suit.

Thanks for the replies, it helps me confirm that I'm on the right track.

On a side note; I wonder if the inherent buoyancy of the wing Vs Jacket BC will be a significant difference?

---------- Post added January 15th, 2014 at 08:58 PM ----------

The table looks good. If you can swim up 5.6lb, you have a balance rig. However, there is one catch. In case of total wing failure, you ditch 15lb belt. Sure you can swim up -5.6lb at 100ft, but as your ascent, you wetsuit expand again. Maybe by the time you reach 50ft, you will be come positive and you will have uncontrolled ascent at that point. You may want to reduce your ditchable weight a bit.

Thank you, that's a very good point. I'll reconfigure my ditch-able ballast weights with that point in mind.

 

[g1138]

The table looks good. If you can swim up 5.6lb, you have a balance rig. However, there is one catch. In case of total wing failure, you ditch 15lb belt. Sure you can swim up -5.6lb at 100ft, but as your ascent, you wetsuit expand again. Maybe by the time you reach 50ft, you will be come positive and you will have uncontrolled ascent at that point. You may want to reduce your ditchable weight a bit.

That or think about flaring on emergency ascent as an option.

 

[rjack321]

The table looks good. If you can swim up 5.6lb, you have a balance rig. However, there is one catch. In case of total wing failure, you ditch 15lb belt. Sure you can swim up -5.6lb at 100ft, but as your ascent, you wetsuit expand again. Maybe by the time you reach 50ft, you will be come positive and you will have uncontrolled ascent at that point. You may want to reduce your ditchable weight a bit.

Swimming up 15lbs is not too bad. I'm more concerned about AL80s in cold water for new divers (<24 dives) further chilled by wetsuit compression, huffing through gas with tunnel vision @ 100ft. Not a good combo. I'd upsize the tank to an hp100 (or lp95) or shallow up the depth ambitions. The wing is a lot less likely to fail in this scenario than going OOA.

 

[JustinRyan]

Swimming up 15lbs is not too bad. I'm more concerned about AL80s in cold water for new divers (<24 dives) further chilled by wetsuit compression, huffing through gas with tunnel vision @ 100ft. Not a good combo. I'd upsize the tank to an hp100 (or lp95) or shallow up the depth ambitions. The wing is a lot less likely to fail in this scenario than going OOA.

I did 1 dive to 104' on air (PADI deeper diver) and that will be the last dive below 80' on Air/additional training. 100' was more for a FMEA. I didn't notice that I was narced until I watched the video. Is it recommended to dive a 7mm and a steal tank? Seams like that would be better for Al80s due to weight.

 

[mala]

That or think about flaring on emergency ascent as an option.

attach reel to ditched weight and use the line as a brake.
you might even get the lead back if you are lucky