Using SMB For Backup Flotation

[mempilot]

Was saving up for a FFM, DPV, and a Meg but decided, "ah what the hell"

A swing and a miss! Where are you trying to go with that statement?

 

[Gombessa]

I just wanted to say that I had a comment to make about SMBs, but it looks like this isn't the topic of discussion here.

 

[deepstops]

Brian,

Neutral at the end of the dive has nothing to do with it. It is the negative bouyancy at the most negative part of the dive that matters, which would be on descent, where a run away descent scenario is most likely to happen. This is especially important on blue water wall dives, and there are accidents documented where this has happened. Swimming up empty AL80's would not require a whole lot of effort, and isn't a pratical example. And since you'd like to call me out on this, let's go do the Lowrance together, descend, put in maybe 10 minutes of BT to accrue some decompression obligation, empty your wing, and watch you come up from the sand and do your stops without a form of backup bouyancy, since you consider your rig to be balanced. When you have a leg cramp from kicking vertically during your ascent and stops, would you like some help? Or, would your cavalier attitude get you through? I can hear the bubbles forming in your joints as I type this.

I don't use AL80s on a 200' dive but if you'd like to try this experiment on an appropriate dive, I'd be happy to. And if you think my attitude toward technical diving is cavalier, you've made a serious error in judgement. Cavalier attitudes don't produce ZERO charlie foxtrot dives, ZERO missed wrecks, or ZERO aborted/missed dives because I use overly complicated gear that's far more prone to failure for simple/basic "tech-light" dives where OC is perfectly fine.

Was saving up for a FFM, DPV, and a Meg but decided, "ah what the hell"

Ouch!

 

[RJP]

Excuse me? Where did I quote you in that post? It wasn't even my post. LOL

The dilusion continues. You're on a roll. Keep going.

I guess I'm taking crazy pills, then:

This is your post, no?
http://www.scubaboard.com/forums/3965821-post68.html


In this post you attribute several quotes to me, no?

Yet, here's the post where those quotes came from, and those quotes are not mine:
http://www.scubaboard.com/forums/3965692-post64.html

Maybe I'm narced? In any case, I will try to avoid the temptation to silt up this thread further.

 

[mempilot]

And if you think my attitude toward technical diving is cavalier, you've made a serious error in judgement.

My comment was addressing your post, and in no way did I push otherwise.

ZERO aborted/missed dives because I use overly complicated gear that's far more prone to failure for simple/basic "tech-light" dives where OC is perfectly fine.

I'll take this as a slight on rebreathers. When you want to have pro/con discussion about OC vs CC, feel free to start a thread.

 

[mempilot]

RJP,

I see what you are talking about now. I have no idea what went on there, because all I did was hit the quote button and answer the points in the post. Why his handle and your handle show up in the same set of quotes is beyond me????

 

[deepstops]

I'll take this as a slight on rebreathers. When you want to have pro/con discussion about OC vs CC, feel free to start a thread.

Rebreathers are a great tool when the dive requires that tool to get the dive done.

But I also have a firm belief problems can be engineered out of the equation more easily than they can be solved. The minimalist approach serves me very well.

 

[Splitlip]

OP and Web Monkey (also I believe) are bothing talking SMB's, not lift bags.

Imagine this:

You are diving a deep wall off Cayman in a 3mm wetsuit with double AL80's. Your wing fails at the threads between the inflation hose and the bladder making maintaining bouyancy with the wing virtually impossible. Any air added just easily escapes out as you add it. All this is happening while you are kicking feverishly to maintain depth due to being negative from the doubles fairly early in the dive. You are sinking against the kick initially at a rate of 30 feet per minute as you deploy your bag. Instead of clipping the snapbolt to your crotch d-ring, you decide to attach it to your reel and blow it to the surface. The bag rises above you and the line jumps the spool, tangling with the force of 50lbs pulling against your mass.

What do you do?

1. Go for a ride and get bent?
2. Cut the line/let go of the reel, and start your descent into the abyss?
3. Did you bring a backup bag and reel to replace the primary in such an event?

None of these are good options in this scenario, which is not fantasy. The appropriate way to use a lift bag to control bouyancy is to handle it the same way you would your other forms of bouyancy. Keep it close to the body so you are in control at all times. A proper 50lb lift bag will have a stainless steel snap bolt at the bottom of the lifting strap. You clip it to the crotch d-ring, add enough gas to it to stop the descent, then gather your wits. At this point, you will not need to add any more gas to the bag, as Boyle's Law will take care of the rest. You slowly give a few kicks to rise just a few feet in the water column, just as you would if you still had use of your wing; all while keeping the bag close to your chest, anchored at the crotch d-ring, and one hand stabilizing the top of the bag and the other hand on the OPRV at the top of the bag. As you rise a few feet, you burp the OPRV, and repeat with a few kicks.

This is any easy task with practice. I've had to do it for another reason I will explain in another post if anyone wants to hear it. Shooting the bag to the surface and reeling yourself up is not an option. Try it, and you will see that you are not going to be able to turn the spool against all that mass, even while kicking your heart out. You will very quickly tire. You need the gas in the bag to lift you, not your arms and fingers on a tiny line and spindle.

 

[netmage]

OP and Web Monkey (also I believe) are bothing talking SMB's, not lift bags.

SMB is a weird term....

Lift Bags are generally considered SMB's among tech divers...
7' Markers are considered SMB's, and some have equiv. lift to a 50lb bag...

I think of these as examples, thru all the discussions in this thread....

1-2' safety sausages generally can not be inflated from depth and thought to survive, as they don't have OPV's to vent on the way up....

 

[mempilot]

OP and Web Monkey (also I believe) are bothing talking SMB's, not lift bags.

For the purposes of this discussion and backup bouyancy, the terms lift bag and surface marker bouy are interchangeable, since a lift bag is often used as an SMB. A true SMB may or may not work safely as an alternative means of bouyancy, since they tend to be very tall and have the OPRV at the bottom, but not everyone uses a 5 or 7 foot SMB, instead, they choose to use a LB as a surface marker.

Here is some simple description provided by Halcyon's product information page.

Halcyon: Lift Device Overview

Halcyon: Closed Circuit Lift Bags