Lift bags for DIR

[patmandu]

Originally posted by Uncle Pug

Not the part about your drysuit failing and that being a reason not to use a CC bag with a wetsuit.....

That didn't have anything to do with the wetsuit/CC bag issue, just another of those 'what if' questions that plauge the quest list and general tech diving type lists. You know, stuff like, why don't you carry 3 masks during a dive? You *could* have a failure in both of the masks and need a third...... The lists are endless.

I'm just glad I dive dry 90% of the time and don't have to worry about not hooking up my LP inflator and sinking to the depths while my buddy waves bye-bye to me and I'm too shaken up to manually inflate or reconnect the hose......

Guess it could happen.:goofy:

 

[aue-mike]

Hi guys-
I would not recommend the Halcyon closed bag. At first impression, it seemed like a good peice of gear. However, upon implementation, it is woefully inadequate and flawed. The valve can not purge gas fast enough resulting in a seam failure and a blown bag. Our group went through several of these bags due to failure. I personally lost three. The welded seam simply is not strong enough the take the load. Whether it is being shot from depth or shot in shallow water with a static load, the bag will fail. I will not bet my life on this peice of equipment. We are still waiting for Halycon to address the design issues and present an improved bag. This is not isolated to Halcyon. OMS has a closed bag and surface marker. I saw one of the big ones explode dramatically on the way to the surface just this weekend (I was on the boat and saw it blow right as it hit the surface -- pretty cool scene).

We have switched to Carter open-bottom bags. However, even these have problems. The bag themselves are constructed of a hard-core material and hold up better than the nylon bags, but the new square-like design creates a waffling-effect and presents difficulty in a fully inflated bag in reaching the surface. You must occasionally stop the reel line and allow the top to swing back up, or else the bag goes up on its side and will reach the surface weakly.

We are talking with Carter to design a better custom bag. It will most likely return to the triangle like design they used to make, and have a perpedincular side pocket at the top to insure a strong-marking bag reaching the surface, instead of a limp bag.

I carry two bags. One is attached with surgical tubing at the base of my backplate. The other is much more accessible. If I am using a scooter, I have one stashed on the scooter body under a section of tire truck tubing. This makes it easy to grab for an emergency, such as a dramatic buoyancy loss or if the scooter floods. If I don't have a scooter on the dive, I have a bag on one of my decompression bottles. I also make sure to have two reels. I have seen lines part, reels nest badly, dropped reels, etc. Even if you have your buddy, I make sure to carry a backup reel or spool.

Regards,
Mike

 

[Lost Yooper]

Wow, thanks for the heads up, Mike. I haven't experienced a problem with mine yet, but I don't use it much either -- just practice. That's a classic Murphy scenario, eh?

Mike

 

[Uncle Pug]

Originally posted by aue-mike
However, upon implementation, it is woefully inadequate and flawed. The valve can not purge gas fast enough resulting in a seam failure and a blown bag. Our group went through several of these bags due to failure. I personally lost three. The welded seam simply is not strong enough the take the load.

What in the world are you doing with these things to blow them up

 

[Uncle Pug]

clean out your box yooper

 

[m&m]

I own a OMS lift bag and a marker, and I wanted to know if any1 else had seen one burst before?

Admitedly I rarely use it to lift loads from the deep, mostly it is for practise purposes and I inflate it with my exhaust bubles, so no truble yet....
thanks
m&m

 

[aue-mike]

Hi Mike-
Yes, we use our bags a lot for the type of deep drift decompression diving we are typically faced with. Another oddity we have found with the closed bags is that they tend to fill with water. How they do that, we could never quite figure it out, but it was normal for us to have to empty 1/3 to as much as 1/2 of an inflated bag of water. That makes it sit lower on the surface and harder to see.

If you design a closed liftbag, you better well design a dump/overpressure relief valve that can keep up with the expanding air. The Halcyon can not do that causing the seams to fail.

Now, some people will say it is "user error" and you should never inflate a bag at depth, but that is downright stupid. It either works or it doesn't work. Saying it is user error when a bag blows is like Firestone blaming drivers for all the blown truck tires. Sometimes you will need to shoot a bag from depth and if that bag can't handle the job, find another bag.

Even Irvine says these are a POS.

Regards,
Mike

 

[Scubaroo]

I'm in the market for a liftbag, and was looking at the Halcyon 80# - I saw a video someone posted in here a little while ago of a diver deploying one of these bags at depth - I noticed he only partially fills the bag (like 1/4 or so) before releasing it, presumably because of the expansion of air as it rises. I guess that the dump valve has a peak flow rate, and because the greatest change in pressure occurs near the surface (air volume of the bag would double in the last 10m/33ft without a valve), it's possible that the bursting bags are a result of the air expansion overtaking the peak flow of the valve. Your observation of a bag bursting at/near the surface somewhat supports this. Is the solution to merely add less air to the bag at depth, and let physics take its course? Or are the bags just too lightweight for the job? Haven't seen one closeup yet.

If these bags are being deployed at say 70 feet, that's a bit past 66 feet or 3 atmospheres, so we could expect the volume at the surface to be about 3 times that at depth, so a bag would only need to be filled around 1/3 to achieve maximum capacity at the surface. Or are they just bursting anyway?

 

[Bullfrog]

I'm carrying a 9'7" 90# OMS SMB. I don't think they'll miss me. The only problem I've had with it, is getting over erectile dysfunction. If you don't dangle a couple of kilos from the bottom of the bag, you have to hang from it to get it to stand up properly.

Presently, I've got it bound-up with some 1" nylon web velcroed to itself. The bag and a spool both hang from the rear D via a double-ender, but I'm strongly considering bungy-ing it to my backplate after Yooper's post.
:thinkingo

 

[aue-mike]

As I mentioned, the problem with the Halycon is that the overpressure relief valve can not keep up with the expanding volume, leading to seam failure. If you are doing recreational dives this may be adequate for a surface marker. However, if you are doing tech dives (this is supposed to be a technical diving forum), using a bag with such limited operating paramaters (e.g., can't be shot from depth past 70fsw) is perhaps not the best bag to use. Heed my advice or don't heed my advice -- it won't affect me. I am simply throwing this out here because it appeared several of you believed this to be a solid peice of gear and since it is Halcyon it *must* be DIR. It is not.

Remember, this stuff is supposed to be life-saving equipment and if something has such an inherent and obvious flaw, there is no way in hell I would use it.

Regards,
Mike