Another SMB question, or two

[fjpatrum]

There are a couple of current threads about SMB deployment. Those, combined with the fact that I'm looking to buy one got me thinking about what I should be looking for in this piece of safety equipment.

If my calculations are correct a 6' sausage, with a 6 inch diameter (is that about accurate?) should have about 70 pounds of lift, when filled completely. The shop I frequent sells these, but they may have a slightly smaller diameter. They sell these with a bolt snap and no reel.

My thoughts for the sausage are primarily for surface signal, not lift of any kind (except in an extreme emergency) and I don't know that I'd bother deploying at any depth greater than my safety stop at this point.

My questions are:

Is the safety sausage ever considered "redundant lift" by any of you experienced divers a la "my BC failed, I have a sausage for lift if necessary"? If so do you buy a larger sausage for that reason or just for visibility?

What are the most "tried and true" methods people have of deploying at depth. I can see a lot of comments about being careful with buoyancy etc while deploying and it makes me think one of the best methods, at depth, would be to transfer air from your BC to the SMB a little and maintain a hold of the SMB until you could adjust your buoyancy properly. Oral inflation, direct from the reg, what are your preferred methods and why? Is one method typically easier for newbs to learn?

Are there any particular features you would look for in a sausage? IE a pocket for/with a whistle or a specific type of closure method or something?

Finally, what is your preferred method of attachment to BC? I was thinking just a couple bungies and a boltsnap to attach it vertically to my backplate. (IE rolled up and "longwise" strapped to the plate. The only other option I can come up with is butt mounted on the bottom of my plate-- am I missing some other choices?

 

[JahJahwarrior]

I like SMB's with these features:
-big. 6' or taller, and nice and wide. i want to be seen!
-open bottom so it can be inflated with any 2nd stage, wing, or my mouth
-quick disconnect fitting without a flange so it can be filled from my inflator hoses but will not latch on to them
-ability to be blown up by mouth
-overpressure relief valve so it won't blow up if i overfill it somehow.

 

[TSandM]

If you are blowing a bigger bag like that, there is a distinct advantage to sending it up from deeper depths. Think about it -- if you send it up from 15 feet, you have to fill the bag almost full where you are, to have it full on the surface. That's a LOT of gas to put in a bag, and a LOT of lift to cope with.

If you send it up from 60 feet, you need only fill it 1/3 of the way to have it full on the surface. This amount of lift is much easier to manage while you are deploying the bag.

I carry mine in my dry suit pocket, but then again, I don't use a 6' bag. I know a lot of folks put them in bungie "slings" along the bottom of the plate.

 

[Crush]

1. What JahJahwarrior and TSandM said;
2. I deploy my SMB at depth (occasionally, for practice) and follow the line up and hang off my safety stop. Deploying at depth is easier as your slight variation in depth will not translate to as large a variation in buoyancy;
3. The post http://www.scubaboard.com/forums/accidents-incidents/365071-bc-failure.html illustrates how an SMB can be used as an alternate lift source - you can climb your way out of a problem, provided that you can deploy the SMB and your reel length exceeds your depth;
4. Small SMBs are easier to store and can be orally inflated. Large SMBs are more visible and you will likely want to inflate them with, say, your octo. I prefer a large SMB, personally;
5. As for features, I look for size, inflation method, and overpressure valve. An open-bottom device may not need an overpressure valve, but it will collapse and lose air at the surface. With an SMB which seals once inflated (but has an OP valve) you can use it as extra flotation on the surface. If the SMB has an opening in the bottom which seals when inflated you can wedge a flashlight into the bottom of the SMB once on the surface - THAT makes for a highly-visible signal;
6. FWIW I have DAN tags (which function as a mirror) and a whistle attached to a single bolt snap which I attach a ring on my SMB. All that safety gear is in one place and thus far it has never fouled as I have deployed it. I shoot all the gear to the surface, then use the whistle at the surface if needed;
7. I have an extra bungee on the SMB to keep it from un-rolling unintentionally. I use my rear crotch strap D-ring as a mounting point.

 

[g1138]

SMB's can be used as redundant lift if your BC fails, but only if it provides a good amount of lift (ie. small signal tubes won't cut it).
You'll want to think about how you'll most likely inflate it. Closed SMB's can only be filled via oral or inflator hose.
Open bottoms can be filled with reg, BC and sometimes oral/inflator hose.
There are some Open bottoms with a special funnel design at the bottom to prevent any air from escaping. (piranha mfg sells one: 6ft)

I have an open bottom one from piranha, 6ft 40lbs lift
I find filling it from my reg to be faster and allows me to worry less about buoyancy compensation because I can deploy it faster, as opposed to orally inflating.

On the topic of securing your SMB, one thing to note from personal experience. I've seen a few SMB's unroll itself when using the attached bungee it comes with. I would advise getting a velcro strap (from a knife or wrist slate)
and using the bungee to attach that to your SMB. That way you'll have a sure tight strap to keep your SMB from unraveling during your dive.
You'll have a bit of extra bungee to loop through your finger spool's center hole which you can then clip to your double ender, keeping everything from flopping around.

I personally do this and then connect the SMB and finger spool to my hip D-ring (I don't have a BP/W =[)
You probably have the choices of your hip D-ring or the holes in your actual backplate.

 

[GrumpyOldGuy]

If you are going to inflate a SMB from depth, bet sure it has an OPV valve. Most larger ones do, some of the smaller ones do not. Like others, I have a hard time deploying from 15', I need to concentrate on maintaining depth at that point, not on messing with an SMB. It is much easier to to from my deep stop (40-60ft) since I am killing time for a couple of minutes anyway. Fill it 1/3 and let it fly.

When diving a W/S, I attached the SMB rolled up to my back plate. It is out of the way and impossible to forget. Easy to pull and launch, impossible to re-stow until I am back on the boat. In my dry suite, the pocket is preferred.

I do consider it a redundant lift device, but a difficult one to control. Pretty much the last line of defense.

 

[dumpsterDiver]

Finally, what is your preferred method of attachment to BC? I was thinking just a couple bungies and a boltsnap to attach it vertically to my backplate. (IE rolled up and "longwise" strapped to the plate. The only other option I can come up with is butt mounted on the bottom of my plate-- am I missing some other choices?

I'll address this one... I attach about 30 feet of nylon string or cord to my 6 ft smb. At the end of the string, I tie a bolt snap. I also cut some lengths of innertube maybe 10 inches long and 0.5 inches wide and tie to the loop of the bolt snap.

When I am done with the SMB, i drain all the air out, and begin to roll it up from the top downward. When it is all rolled up, then i wrap the 30 feet of cord around it.

When I come to the end where the bolt snap is tied, I then use 2-3-4 loops of elastic innertube to tie the SMB and sting into a secured bundle. This leaves me with a tightly bound SMB, with the bolt snap secured to it with my elastic bands. i can clip it off anywhere and it will not unravel.

I generally run a very heavy piece of comercial fishing line from the bottom of my BC to form a 6-inch loop and i clip the smb here. It rides on my butt between the tank and my butt.

When i want to deploy, I unclip the smb, slip the elastic band off and then allow the smb to spin and the heavy clip sinks pulling the line off and eliminating the chance for entanglement. When i reach a depth of about 30 feet, I add some air, let it go and allow the line to slide through my hands and then i catch the bolt snap.

This configuration allows you to avoid using a reel or a finger spool, but of course your deployment depth is limited to the length of the string.


This video http://www.youtube.com/user/whatandwhen2#p/a/u/1/CE3cPJ40N7w

at the time of about 35 seconds shows my 12 yr old practicing (with a small one) while we drift in 60 feet of water. He falls prey to the common problem of perceptual narrowing (ie.g., concentratin on the task rather than being aware of his depth) I allow him to fall away and screw up, but it is part of the learning process.

I feel it is important to have the SMB attached to a line to allow deployment prior to surfacing, since a marker over your head may save you from boat traffic and there are other benefits as well.

 

[Puffer Fish]

I have three different sizes... depending on where I am diving and how important it is to have something large.

The largest one is wrapped and clipped off to the left side ring on the belt of my BP/W. The other two are in a mesh pouch that attaches to the bottom of the plate.

If I am deploying it every dive (like the dry tortuga's), then I carry a reel, if it is just for emergencies, then a spool, attached to the right side ring.

All have open bottom w/duck valves, over pressure valves and most have a manual inflate valve.

If one is ever going to use one for a bad BC, it needs to have the over pressure valve and they need to learn how to hold it and dump air as you ascend.

If I am using the 9 ft (only 8 ft is actually filled), then deeper is better.

Even then it is a bit of a dance to actually do. Get reel/spool, open smb and attach spool. Unfurl the smb above you. Use either your octo or your primary, and in one motion, exhale..start to sink, pull down on the smb, hit purge, hold for just over one second and let go...making sure the spool is in a good unreel postion.

If you do it correctly, you end up in about the same depth you started.

Twice I have had the line catch, and had to just let it go (you will not stop a bag with 75lbs of lift from going up). I now carefully rewind the spool after every use.

Note: The exhale serves two purposes, first it compensates for the lift while filling, and second, if for some reason it does drag you, then at least you don't have lungs filled with air.

Two people can do this a lot safer, with the line holder taking care of the line and the other person just inflating.

I also use them for marking spots on the bottom to get a gps reading later..and have used them to attach a stringer to when there are a lot of sharks around.

 

[DevonDiver]

My choice of DSMB depends on the dive I am planning.

I mostly dive in calm, tropical waters. I don't need a large DSMB to be seen in rough water. I use a small halcyon oral-inflate DSMB, that I typically deploy on approach to, or during, my safety stop. I like these because they can be inflated by one large breath. Because the air in my lungs is being transfered into the bag, it doesn't cause a change in buoyancy. I release the bag as I inhale. For simplicity, I use a finger reel to shoot these bags.

When I am diving from deeper/tech depths, or in high current, then I will use a large capacity 5' bag. These are deployed from at least 30m depth, so again, a single long exhalation into the bag will be sufficient for full inflation (account for air expansion on ascent). I use semi-sealed, open-ended bags... inflating it using the exhaust bubbles from my primary reg.

If I did have to use a bigger bag from shallow depths, then I'd still use the exhaust bubbles from my primary reg. However, rather than doing multiple exhalations, I would speed up the process by using my purge valve.

For deployment, my right hand is always controlling my reel - holding it away at arms length with the line taught to the bag in my left hand. The left hand controls the bag and the inflation process.

 

[mjatkins]

Because the air in my lungs is being transfered into the bag, it doesn't cause a change in buoyancy.

Thanks for this, I was just having the same thought.

I carry an SMB on every dive, and deploy it on every dive. I use it so that the boat (as well as other boats) know that I am sending divers up, or am surfacing with students. I have had small ones, as well as large ones, and using oral inflation is never an issue as long as I only put one breath into it. I am currently using a 6 foot sausage, and if I am shallower than around 60 ft when I send it up it the one breath wont have it full when it gets to the surface. Then it only sticks up 4 ft instead of 6. No big deal. As Devon diver said, it is simply a matter of moving air from the lungs to the SMB, and then letting it go as you inhale from the regulator.