Purpose of an SMB?

[Crush]

question... how do these SMBs usually stay upright at the surface? I would think that they would just fall over when they hit the surface. What about if there are winds, will they tend to fall over?

When ascending on a line/rescue sausage, I make sure that I am somewhat negatively buoyant. Hanging off the line keeps the rescue sausage vertical (as Tortuga68 mentioned).

 

[deepdvr1]

GUE Fundamentals would be a good course to learn this skill.

 

[D_B]

Seeing as this is in basic scuba I'll share what I thought was the most helpful thing I learned when I first did mine.

when you come to your stop and go to rig your SMB for deployment, don't look directly at it while doing so, do it "out of the corner of your eye" using your peripheral vision while looking at the particulate matter in the water, it provides direct and instant feed back to see if your rising or dropping while your "distracted" by your SMB .. made my depth holding much easier

One thing mentioned to us when doing it for the first time is to do it at the end of your safety stop , that way if you rise up during a not so perfect release, it's at the end anyway ... yeah, the very first time is a learning experience .. just remember this when you inflate it .. when it pulls, you let go, NOW! :blush:

 

[Tortuga68]

It should be part of OW IMO but it's been dumbed down so much now you're lucky if they teach you how to put a reg in your mouth with some agencies

 

[D_B]

I think that OW might be a bit early, I remember mine (3 weeks) and unless your taking a four week course , I think that would have been one thing too many for me .. I remember the stress of OW because .. it's all new, all so important, thinking my life depends on it

 

[Crush]

dougchartier,

For the reasons mentioned by D_B and others, I find it easier to deploy a rescue sausage below 40 feet than at, say, at 20 feet. The deeper you are, the lesser the volume or air (at depth) you have to put into the rescue sausage to have it fully inflated at the surface (the air expands as it rises). This means that you will have to deal with a smaller buoyancy change at depth (owing to the rescue sausage trying to pull you up as you hold onto it to fill it). Having said that, I am not advocating that you first try to deploy your rescue sausage at a challenging depth.

 

[D_B]

Mpetryk .. yes, my dive buddy that time was pufferfish and he would deploy his at 40 feet and told me the same thing as you when I complaned it was hard to get enough air in the SMB at 20 feet to have it fully inflated on the surface, without having it try to drag you upwards while filling it

 

[Tortuga68]

I think that OW might be a bit early

I understand your point, but it's a valuable skill nonetheless

This means that you will have to deal with a smaller buoyancy change at depth

Lift is lift, regardless of depth

 

[TSandM]

Lift is lift, regardless of depth

Um, actually, no. If that were true, nobody would ever have a runaway ascent. If you put one liter of air into something at 100 feet, at 30 feet you have two liters, and they displace two liters of water, and therefore create more lift.

It is easier to shoot a bag deeper for the reasons already given. You just have a huge amount of line to your spool to spool up or otherwise manage on the way to the surface.

One tip for those who are shooting bags in the shallows (safety stop). There is no need to spool up the line on ascent. You can get to the surface, and fairly rapidly do it there. (This doesn't work from 70 feet, though )

mpetryk, I'm not sure what distinction you are making between an SMB and a rescue sausage. I haven't seen the latter term before. To me, it's a DSMB if it can be deployed at depth, and a safety sausage if it is designed to be inflated on the surface. A DSMB can be used for a variety of things, including towing as a dive marker (not sure if it's a legal dive "flag" everywhere or not) or deploying at the end of the dive as a signal to the boat.

 

[Tortuga68]

If you put one liter of air into something at 100 feet, at 30 feet you have two liters, and they displace two liters of water, and therefore create more lift

Yes but that's not what I was talking about - maybe I expressed it poorly, sorry

What I was trying to say is that lift is lift at the same depth, regardless of volume

The deeper you are, the lesser the volume or air (at depth) you have to put into the SMB to have it fully inflated at the surface (the air expands as it rises). This means that you will have to deal with a smaller buoyancy change at depth

This is the point I was trying to address

When you deploy your SMB, the lift generated will be related to the volume of air that you have put into it, regardless of the depth you deployed it at

As you said, once you let it go, the lift will increase as it ascends

But unless you **** up, that lift won't be applied to you

Either way, you won't have a "smaller buoyancy change" to deal with at depth