SMB inflation issues

Hi, hope this is not a repeat of a frequent question but did not see anything exactly like this. I took a GUE fundamentals course this spring and and have been practicing SMB deployment but I still stink at it. I can't get enough air orally into the SMB at any depth to do a solid deploy. I thought this was my fault but now I wonder if it is the SMB. I have an old SMB that uses the twist lock style valve that must be depressed to inflate. All the air seems to escape out the side of my mouth and very little gets into the SMB when I try to inflate under water. Surface inflation is no problem. My instructor's SMB is a Halcyon with a non twist valve that could be LP inflated but will also orally inflate. Is this type of valve significantly easier to inflate at depth? Anybody have any recommendation on orally inflated SMBs or techniques that may solve my issue? Could also do a semi closed SMB if that is the way to go. LDS owner and instructor would definitively prefer I buy Halcyon since he is a a big fan of them and sells their equipment. I would like to become a technical diver before I am to old to dive anymore so appreciated any help.

Thanks

Blow it up slowly and don't allow air to leak out around lips... Easy to say, but hard to do in very cold water when the lips are numb and lip muscles are weakened by cold.

I use an open end SMB which I inflate with my inflator/reg. I find this the easiest. I use the other SMB as a surface marker instead since it is easier to deploy on surface. Will post my SMB since I picked it up online.

I have the same problem, because by the time one is shooting a bag up here, one's lips are usually pretty numb. I have found the Halcyon bag with the oral/LP inflation valve to be by far the easiest to use. The large flange around the opening allows an easier seal (although I sometimes still have to hold my lips together with my fingers). Not having to push inward to open the valve makes it much easier.

This is one place where I think equipment design makes a really big difference. Try the Halcyon bag; I think you'll like it.

surfacemarker.com
Just thought I would post my SMB. It is good quality and is open ended if you like that type of SMB. Otherwise Halycon has some really awesome SMB's that are significantly more but higher quality.

Thanks everybody for the replies. I feel better know I am not the only SMB inflation challenged person out thee. I will definitely take a look at the alternative types you have recommended.

Thanks again

I have not tried it (yet), but I saw one guy who put a short piece of surgical tubing around his oral inflator valve. He said it made it 10x easier to seal his lips around. I think it was a DAN SMB. It was a pretty thick wall as I recall.

mweaver40:

Thanks everybody for the replies. I feel better know I am not the only SMB inflation challenged person out thee. I will definitely take a look at the alternative types you have recommended.

Thanks again

Click to expand...

When i started diving, the life vests had the EXACT same oral inflator and no power inflator from the tank. I was so happy when I bought my first horse collar vest which had a large mouth piece and a large diameter corregated hose like we now use.

In 40 degree water, it was very hard for me to get air in those damn vests.

A little more clarification is needed here. There are three types of SMBs:

1. Open circuit. The SMB is completely open on the bottom - pretty much an inverted sock that can be filled by bubbling air in the bottom by mouth or with a second stage. But it ca dump the gas if tension on the line is not maintained, allowing it to lay flat on the surface.

2. Semi- closed circuit. The SMB is open on the bottom but uses a cone shaped valve that allows air to be bubbled into the bottom by mouth or with a second stage, but helps retain the gas if the bag is laying flat on the surface. They do however require an OPV to prevent rupture due to gas expansion as they rise to the surface.

3. Closed circuit. The SMB is a closed system filled through an inflator stem. Thee bags will require an OPM to prevent the bag from potentially bursting on the way to the surface. But they will stay inflated indefinitely even if laying flat on the surface.

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Size matters.

I see technical divers in training using a small, skinny, 3-4 ft tall SMB to make it easier to fully inflate the SMB in training, usually launched from shallow depths, in order to meet a course standard. I don't think that transfers well to the real world where a skinny 3-4' tall bag is very hard to see at any distance in 3-4' waves.

Personally, I'd rather have a half inflated 6 or 7 ft SMB than a fully inflated 3 or 4 ft SMB as the larger SMB will be much wider and easier to see. And when launched from depth coming off a wreck, a 6 or 7 ft SMB does not take that much gas to fill when you're launching it from 150-200' ft.

On the other hand, it takes a degree of negative buoyancy to get an SMB to stand up. That is only a pound or so with a 3-4' SMB, but is more like 5-6 pounds for a 6-7' SMB. Consequently a tall bag is difficult to use in a recreational situation where a diver is near neutral at their safety stop with no gas in the wing or BC.

Just to put bag size versus inflation in perspective, most manufacturers of SMBs (semi-closed circuit models with an over-pressure valve and oral and/or one-way bottom fill) indicate buoyancy when full. That can be converted to air volume. I measured my full-to-deflated lung capacity by repeatedly blowing air into a graduated 2½ Liter plastic bottle using a short hose and a deep sink. One Liter of air equals 2.2 Lbs (2.264 Lbs in sea water) of displacement.

I came up with a little over 4 Liters. So for me, that is about 18 Lbs displacement with one lung-full filled from 33 FSW after the bag hits the surface. Many 6' tall SMBs are rated ~30 Lbs so the bag would be about half full. It would be about 27 Lbs when inflated at 66 FSW.

Unless I am orally filling deeper than about 60', I try to get two lung-fulls in the bag. Here is the sequence that is working for me.

1. Blow a little into the bag to make it unfurl and stand upright for easier handling.
2. Get the reel and line sorted out and exhale a large lung-full into the bag.
3. Replace regulator but breath shallow
4. Dump gas from the BC and/or drysuit until neutral holding the bag with a large lung full of air.
5. Blow the second lung-full into the bag
6. Replace regulator
7. Release the bag on the reel before sucking in too much air

This technique gives me an essentially full bag shot from 33'+. It also leaves me heavy as I am winding the reel up towards a stop, which I find easier with a little tension on the line. Of course, the other downside of a 6'+ bag is figuring out how to carry the beast due to the significantly larger size.

DAN is advertising, but not yet delivering, an updated version of their 6' bag with light reflective strips down both sides and an imbedded radar reflector. It will be interesting to test the effectiveness of the radar reflector. A friend has a radar equipped boat and an old DAN SMB for comparison. Detectable distance will vary a lot based on radar quality and operator skill, but I will post my impressions when I get them. It would sure be nice if the new SMB really lights up the blip.