Lift bag versus SMB for tech divers?

[texdiveguy]

Huh? There is a standard?

Nothing in concrete/just a rule of thumb based on the dive teams direction-briefing....but in most USA locals yellow is a standard bag to shoot first as if saying--'all ok'....orange is resv. in many situations for 'hey I need assistance/emergency/attention!!--getter for slated note.

 

[Rick Inman]

If using a lift bag as back-up bouyancy is part of your contingency planning, you need a dump to help control your ascent and keep nuetral at your stops.

Why not just sent it up on a line and reel yourself up the line? Much easier.

I carry both a 6' SS and a 100# (I think, don't remember) bag.

As to color, my SS is orange on one side and yellow on the other. So if I ever use it in the UK, as it twists in the wind, the guys on the boat will say, "He's having an emergency!...well.. no, I guess he's Ok... No! It's an emergency!!.... Well, I guess he's alright..."

 

[Meng_Tze]

Never heard of any standard on this, not in Europe either. Some boats in a region may request the same thing (Yellow first, Orange for emergencies for instance), but that is hardly a standard and can change from boat to boat, city to city and country to country.

The key is to agree with surface support what/how you will communicate through these devices. But let's not make it more than it really is: all over the place

 

[texdiveguy]

Never heard of any standard on this, not in Europe either. Some boats in a region may request the same thing (Yellow first, Orange for emergencies for instance), but that is hardly a standard and can change from boat to boat, city to city and country to country.

The key is to agree with surface support what/how you will communicate through these devices. But let's not make it more than it really is: all over the place

Thats what I was saying....nothing in concrete.

 

[battles2a5]

Why not just sent it up on a line and reel yourself up the line? Much easier.QUOTE]

Rick,

If your wing fails at the beginning of a dive, when you very negative (full doubles/stage/deco bottles at least 25 pounds neg.), I would not want to pull all of that weight up with just the line. If it snaps, you are SOL and without a marker. Also, if you are in any sort of overhead, shooting the bag won't get you anything but a bad day. I thinks its much easier to inflate your bag and then control your bouyancy using the dump valve. Just my opinion.

Ryan

 

[grazie42]

CMAS has a standard for colour-coding and (almost) everyone follows it. Certainly the member-organizations like BSAC etc do...you always need to check with your skipper but at least there is a "starting point". The standard isn´t really enforced on rec-trips (most recdivers only have one anyway). Often an smb on a rec-dive is a sign of distress so definetely talk to your skipper before the dive on what different ones mean (skippers are seldom divers)...

Here are the smb-standards (http://www.cmas.org/comtec/standards.asp?cl=77&sub=77): You can also find all the other standards there as well so might be worth a browse...
Recommended system of signalling using DSMB’s
Red DSMB = Indicates the position of a diver below ascending normal.
Yellow DSMB = Diver in distress, requires assistance. The buoy may be accompanied by an
attached note determining the required help e.g. ”More air”.
Red DSMB + Yellow DSMB = Red DSMB is usually sent up first to indicate a normal ascent and to the diver’s position. The second DSMB, Yellow, is deployed to say I now need assistance.
Again a note may be attached to determine the required help.

 

[khacken]

In my Naui Tech class we were told that you have to have one yellow and one orange lift bag or smb. It is doesn't matter which is which. On the dive planning sheet you write down what color means emergency and what color means you are ascending and you are ok. If you are in an area where there is a standard, for instance yellow means emergency, then you would follow that standard. If not, then the surface support team and the dive team would agree on the colors.

If you need to lift something, use the lift bag. If you are try to be seen use the SMB.

 

[Johnoly]

I thinks its much easier to inflate your bag and then control your bouyancy using the dump valve. Just my opinion.

Ryan

Most dump valves are at the bottom of the bag/smb. If weighted a little heavy at 15ft and air rises to the top of the bag/smb, how would you control a half full bag and use the dump valve to keep it from being a run-away towards the surface?

I do agree that a SMB can help in bouyancy, but it takes a lot of practice.

 

[texdiveguy]

Most dump valves are at the bottom of the bag/smb. If weighted a little heavy at 15ft and air rises to the top of the bag/smb, how would you control a half full bag and use the dump valve to keep it from being a run-away towards the surface?

I do agree that a SMB can help in bouyancy, but it takes a lot of practice.

Johnoly... in fact the dump valves on 'lift bags' are located at the 'top' of the bag opposite end from the fill hole....short and snappy bursts are used to control the bag on your hopefully controlled assent.

 

[BarryNL]

Most dump valves are at the bottom of the bag/smb. If weighted a little heavy at 15ft and air rises to the top of the bag/smb, how would you control a half full bag and use the dump valve to keep it from being a run-away towards the surface?

I do agree that a SMB can help in bouyancy, but it takes a lot of practice.

An SMB has the dump valve at the bottom - it's designed to be filled and released. As such it's not a particularly good device for backup buoyancy during an ascent. It can, of course, provide extra flotation buoyancy on the surface.

A lift bag has the dump valve at the top and is designed so that you can vent air during a controlled ascent - after all, you don't want whatever you're lifting to go into runaway ascent mode. As such, it's a much better option for backup buoyancy and should probably be considered required equipment when diving a single bladder wing with a wetsuit (and IMHO a drysuit too).