shooting smb from depth

[Jax]

I can't agree with this. The penalty of screwing up in shallow water is far worse than in deep water. The deployment of an SMB is perhaps the one skill that is easier and safer at depth.

Ahhhh, I missed a point in clarity -- practice in shallow water without going to depth -- it assumes you don't on-gas much nitrogen, and as long as you keep saying, "**** - **** - ****" as you go up, you'll be exhaling.

 

[Jax]

For practicing don't use such a big bag.

Someone started a thread about that -- something about "train as you will fight (dive)" . . . .

I practice with the gear I will be using.

 

[DevonDiver]

I prefer a reel and why not take advantage of the class to learn with a reel. As for depths and the need for a reel when I did my ANDP it was helitrox so we were makin dives to 150 feet add in some current and you could easily lay out 200-250 feet of line deploying a SMB from the deck. nice to have a reel at that point. Just my two cents. There is more than one way to get things done.

There is more than one way. I hope it didn't come across that I was suggesting otherwise?

That was just the advice I would give to someone in his situation. The best course of action would be for the OP to communicate with his future ANDP instructor to clarify what course of action he felt was applicable.

Transitioning from rec to tec training, many student divers don't realise that their instructors should be much more communicative and involved in helping them prepare for the course.

 

[Akimbo]

I prefer a reel and why not take advantage of the class to learn with a reel. As for depths and the need for a reel when I did my ANDP it was helitrox so we were makin dives to 150 feet add in some current and you could easily lay out 200-250 feet of line deploying a SMB from the deck. nice to have a reel at that point. Just my two cents. There is more than one way to get things done.

Me too. To me, winding the string back on the reel is the deal maker and deploying is icing on the cake. I hate winding string on a finger spool. I find that I can easily wind my way up the line at 30'/second. With the right handle I can still have some use of that hand to help with inflation.

The power versus oral inflate argument is worth thinking through. This is a portion of another post that applies:

…There is serious trade-off between sizes. Too big and they are difficult to carry due to bulk and inflate due to air volume. Too small (short) and they are difficult to see on the surface, like in sloppy seas or from a distance due to swift currents.

If you are after an SMB, then there is the “how full” consideration. Deploying an SMB on a thumb reel, in a current, in kelp, and/or in bad visibility can be tricky. Add an LP inflator to the mix and you have the potential to take a way-too-quick ride to the surface due to entanglement… not a good thing if you were deploying for decompression.

For many, an ideal option is to inflate the bag orally and release it on the reel before you take a big lung-full of air, thus remaining near neutral on the bottom or mid-water. Gas expansion will hopefully inflate the bag enough to serve your purpose. A partially filled bag will float to the surface and allow you to lightly hang on the line for decompression, but may not stand tall so it can be easily spotted from the boat. An example where this would be problematic is doing a drift dive that requires decompression. Granted, you can fully inflate it on the surface so it stands tall, but meantime you may have drifted a long way.

Let’s say you can exhale 4 liters of air. Inflated at 33', it will provide 18.1 Lbs of buoyancy (in sea water) at the surface. A typical 6' SMB has about 40 Lbs of lift so it will be less than half full. Inflated at 66' you get 27.2 Lbs surface displacement out of the deal. If that is enough for your purposes, it isn’t worth the trouble to use power inflation (BC hose or second stage). With a little care, you can blow 1½ to 2 breaths into the SMB without great risk to playing Trident Missile. Power inflation is great, but know in advance that you can blow 40 Lbs of buoyancy in that tube PDQ on the bottom. Check YouTube, there are tons of videos....

 

[mikemill]

Someone started a thread about that -- something about "train as you will fight (dive)" . . . .

I practice with the gear I will be using.

A 5lb bag is all most people will need. It is better to get the basics down with a smaller bag and then move on to a bigger bag then try to screw around with a big bag in 20' of water (which you aren't going to be able to fill enough to have it looking good on the surface)

 

[Jax]

A 5lb bag is all most people will need. It is better to get the basics down with a smaller bag and then move on to a bigger bag then try to screw around with a big bag in 20' of water (which you aren't going to be able to fill enough to have it looking good on the surface)

I don't care how 'good' it looks -- if everything is good to go, the boat will spot a half-filled 8' smb. If things are not so good, I complete the fill at the surface, add a light if necessary.

 

[Ste Wart]

Maybe skip the AN/DP course and take a Cave course instead, that way you avoid the 'little orange rockets of death'

 

[Akimbo]

A 5lb bag is all most people will need. It is better to get the basics down with a smaller bag and then move on to a bigger bag then try to screw around with a big bag in 20' of water (which you aren't going to be able to fill enough to have it looking good on the surface)

I don't care how 'good' it looks -- if everything is good to go, the boat will spot a half-filled 8' smb. If things are not so good, I complete the fill at the surface, add a light if necessary.

Sometimes, maybe even usually. I am reluctant to make such a recommendation without knowing more. Some people carry an SMB so it can act as a lift bag as well. Others are decompression diving far offshore in the Gulf Stream off Hatteras. It is all about understanding the trade-offs and choosing the least painful compromise.

My one recommendation is don’t get a bag that is so large when folded or rolled that you leave it onboard most of the time because it is a PITA to carry.

 

[MXGratefulDiver]

So the only guy who actually answered the question suggested it in a way that I wouldn't, personally, recommend ... I learned in my AN/DP class why you never want to clip the reel to your body for deployment when my reel jammed and I had to release it at depth with a deco obligation. If it had been clipped, it could've been very bad juju.

Here's my method ... using a 400' Salvo reel and a 50-lb semi-closed SMB ...

- remove reel and bag and connect them together (if not already done)
- pull retaining bungee from the bag and put a slight amount of air in the bag ... just enough so the bubble makes the bag "stand up" in the water
- release the lock on the reel, and apply a bit of pressure on the reel with your thumb, to prevent it from unwinding
- remove your primary and put your backup in your mouth
- hold both the reel/bag and primary at arms-length to avoid the potential for snaggery
- use the primary to inflate the bag
- keep a (very) slight tension on the reel with your thumb as the bag surfaces ... to prevent the reel from rat's nesting
- once the reel stops spinning, lock it down

Key points ...

- putting a little bubble of air in the bag initially makes it easier to manage ... you can then use just one hand for bag and reel, freeing the other up for the regulator exchange
- keep a bit of pressure on the reel while it's deploying ... not enough to interfere with the deployment, but enough so the reel doesn't spin faster than needed for the ascending bag ... that avoids potential rat's nesting issues. If your reel has a clutch, use the clutch ... just don't overdo the pressure setting. In either case, use just enough pressure to avoid the reel free-spinning.
- hold the reel and bag far enough out in front of you so that if anything goes south you can release the reel without it entangling in any part of your equipment

I agree with those who say practice shallow first ... the consequences of worst-case failures are a lot less severe that way ...

... Bob (Grateful Diver)

 

[MXGratefulDiver]

Sometimes, maybe even usually. I am reluctant to make such a recommendation without knowing more. Some people carry an SMB so it can act as a lift bag as well. Others are decompression diving far offshore in the Gulf Stream of Hatteras. It is all about understanding the trade-offs and choosing the least painful compromise.

My one recommendation is don’t get a bag that is so large when folded or rolled that you leave it onboard most of the time because it is a PITA to carry.

Good advice ... equipment's only worthwhile if you have it on you when needed. But I'd caution about using an SMB as a lift bag ... unless you're letting go of whatever you're lifting and letting it fly to the surface without you.

Lift bags have an OPV near the top of the bag ... to allow air to be released as you swim the bag to shallower depths. SMB's typically have the OPV near the bottom of the bag ... where letting expanding air out of the bag becomes much more problematic ...

... Bob (Grateful Diver)