Shooting a bag (DSMB) in strong current conditions

[CWK]

The SMB is the tool that's used to tax other skills like buoyancy and trim. Complicating the deployment of the SMB isn't designed to make you better at shooting a bag, they could do the same thing without having them separate.

OK. So we are now talking about bouyancy and trim. Let me post a video again so that we all know what we are talking about.

In this video, the diver clips off his double ender at 0:40. Note that he is doing things at a leisurely pace. He releases the SMB at 1:05. From clipping off the double ender to release of SMB is what I consider the core part of SMB deployment. This is the part where we want to develop muscle memory. The diver completes the core part of SMB deployment in 25 seconds at a leisurely pace. He could do it in 20 seconds if he wanted.

In terms of training SMB deployment, you can complicate things before and after the core part of SMB deployment so that you do not interfere with development of muscle memory for the core skill of SMB deployment. Checking depth during the core 20 seconds is unnecessary. Ironing out a SMB is totally unnecessary. If you want to add complications, add a depth check at the very beginning and at the very end of the exercise. If you want to complicate further, have the diver start with the line and SMB seperate instead of attached. But do not add unnecessary elements to the core part of SMB deploymet because it interferes with development of muscle memory.

In terms of bouyancy and trim. The diver in the original current video has to continually monitor bouyancy and trim because she is in a very unique position. She has a reef immediately below her and a strong current above. She is either on a ledge or there is a coral head in front of her that is sheltering her from the full force of the current. If she drifts up a 1m, she will be swept away by the current. If she drops by 1m, she will hit the reef. By all means give her a simple task like SMB deployment and make it more complicated than necessary in order to task load her. But do not mess with the core part of SMB deployment in the process because it is intefering with the development of muscle memory for this procedure. And it is totally unnecessary to make her look at her computer to check her depth. She is in a position where she cannot drift up or down by more than 1m, and she knows that. Telling her to look at her computer to check her depth is adding a totally unnecessary element that is not logical because she knows her depth without looking at her computer. In a sense, her depth is unimportant. She has to ensure that she does not hit the reef below her and that she does not drift above whatever is in front of her that is sheltering her from the current. Monitoring her position within her environment is important, not the depth shown on her computer.

I don't think we disagree on task loading and muscle memory. We can disagree on how to achieve this.

 

[JohnnyC]

OK. So we are now talking about bouyancy and trim. Let me post a video again so that we all know what we are talking about.

In this video, the diver clips off his double ender at 0:40. Note that he is doing things at a leisurely pace. He releases the SMB at 1:05. From clipping off the double ender to release of SMB is what I consider the core part of SMB deployment. This is the part where we want to develop muscle memory. The diver completes the core part of SMB deployment in 25 seconds at a leisurely pace. He could do it in 20 seconds if he wanted.

In terms of training SMB deployment, you can complicate things before and after the core part of SMB deployment so that you do not interfere with development of muscle memory for the core skill of SMB deployment. Checking depth during the core 20 seconds is unnecessary. Ironing out a SMB is totally unnecessary. If you want to add complications, add a depth check at the very beginning and at the very end of the exercise. If you want to complicate further, have the diver start with the line and SMB seperate instead of attached. But do not add unnecessary elements to the core part of SMB deploymet because it interferes with development of muscle memory.

In terms of bouyancy and trim. The diver in the original current video has to continually monitor bouyancy and trim because she is in a very unique position. She has a reef immediately below her and a strong current above. She is either on a ledge or there is a coral head in front of her that is sheltering her from the full force of the current. If she drifts up a 1m, she will be swept away by the current. If she drops by 1m, she will hit the reef. By all means give her a simple task like SMB deployment and make it more complicated than necessary in order to task load her. But do not mess with the core part of SMB deployment in the process because it is intefering with the development of muscle memory for this procedure. And it is totally unnecessary to make her look at her computer to check her depth. She is in a position where she cannot drift up or down by more than 1m, and she knows that. Telling her to look at her computer to check her depth is adding a totally unnecessary element that is not logical because she knows her depth without looking at her computer. In a sense, her depth is unimportant. She has to ensure that she does not hit the reef below her and that she does not drift above whatever is in front of her that is sheltering her from the current. Monitoring her position within her environment is important, not the depth shown on her computer.

I don't think we disagree on task loading and muscle memory. We can disagree on how to achieve this.

You're free to form your own opinion. I disagree. As a technical, CCR, cave diver, and divemaster, I disagree. And all of the agencies that I've done advanced training with do as well.

By your own admission you're very new to this. I suggest you seek out actual training before coming to conclusions based on some videos you've watched on youtube.

 

[CWK]

You're free to form your own opinion. I disagree. As a technical, CCR, cave diver, and divemaster, I disagree. And all of the agencies that I've done advanced training with do as well.

By your own admission you're very new to this. I suggest you seek out actual training before coming to conclusions based on some videos you've watched on youtube.

I am delighted to disagree with you. When I was doing my undergraduate and post graduate studies, I often disagreed with my professors. It was part of the intellectual discourse expected in academia. It should be noted that even professors disagreed amongst themselves - i.e. even academic professors could be wrong. It was not too long ago that conventional wisdom said that the earth was flat, and that the earth lay at the centre of the universe. Conventional wisdom changes with time.

I say that there is no need to iron out the DSMB because inflating it straightens it out naturally. You and all the agencies that you have done advanced training with may disagree with me. That is cool.

I say that the diver in the OPs initial video does not need to check her computer for her depth, bouyancy and trim because she is continually doing that with reference to the specific environment that she is in. You and all the agencies that you have done advanced training with may disagree with me. That is cool.

I say that the diver in the OPs initial video should check that there are no divers above her before deploying her DSMB. You and all the agencies that you have done advanced training with may disgree with me. That is cool too.

I have said in earlier posts that I was certified 30 years ago and that I resumed diving in April last year. Since the resumption of diving 12 months ago, I have taken the following courses:

Recreational
Night dive speciality
Deep dive speciality
Wreck dive speciality
Drift dive speciality
Self Reliant diver speciality
Rescue diver

Technical
SSI Technical foundations
SSI Extended range nitrox

Earlier in this thread I had expressed the intention of doing the Padi Tec 40, 45, and 50 courses. My suspicion is that even when I have enhanced my training, we will still disagree an many things. That is also cool.

 

[JohnnyC]

My point is, there's a reason we do things the way we do, and we teach things the way we do. Getting an education by way of youtube is rarely adequate, especially when people who do have the training and experience are telling you otherwise and offering advice, free of charge by the way. You've made statements of fact without basis. Disagreeing from a position of ignorance does nothing to bolster your position.

Expressing a desire to take technical training from an agency that barely does recreational training adequately does not bolster your position either.

So, as someone who is actually very experienced in this, I'll specifically address a few of your points.

1) We hold position in a current because sometimes we have to hold out position in a current. Having a student do this during training dives addresses this. Sometimes we have to hold position in a current while doing other things. Lazily drifting along doesn't always work. Being able to manage a task-loaded situation while holding position in current is an important skill to have. Your recent round of instruction should have covered this.

2) We check our depth often, because holding proper depth is significantly important for many aspects of diving, from beginning to advanced. You posit that the student should only check depth before and after. Would you advocate for this during a gas switch to a decompresison gas? Would you advocate not checking your MOD on every switch? If you advocate the same lack of awareness during that process, that's a good way to allow an untoward situation to progress down the accident slope. By getting the student in the habit of making a depth check part of their routine when doing things like shooting an SMB, it reinforces that paradigm when this behavior is a lot more important. Gas switching protocol should have no less than 3 depth checks at different stages, it's that important. You should be doing 3 checks while shooting an SMB. You should be checking when you arrive at your stop depth, checking before you shoot the SMB, and checking after you've locked it off. It's easy, takes half a second, and prevents issues.

3) We "iron out the SMB" (although the OP is more demonstrative than normal) to ensure that the SMB will deploy cleanly. This is not always the case. I've seen it happen, and I guarantee it will happen in the future to many people, possibly even you. Most of us use a quick swipe to unwind the full length of the SMB, but if the student in the OP wants to hand smooth it flat, no big deal. We do this because clean deployment is very important. Blowing up a rolled SMB may indeed work 99/100 times. But the time it doesn't, because you didn't make sure the SMB could cleanly deploy, could cause quite a significant issue. I have personally seen a rolled SMB, in current, tangle itself into a divers snorkel and pull her mask off, because it unfurled directly into her head.

4) Imagine dealing with a fouled SMB that didn't deploy cleanly, in a current, while maintaining depth in blue water, during a decompression stop. This is why skills are stacked, even over a shallow reef, even when drifting would be easier, even with a visual reference.

5) You are absolutely correct, she should check above her before launching her sausage. It's one of the issues I have with the student in the OP, but something that's very easily correctable and not worth fussing over.

In the past 12 months you've taken 4 specialties of essentially no value, 2 of marginal value depending on your instructor, 2 foundational technical courses that should have covered all of this, which leads me to believe that they were less than rigorous.

There are a lot of things in dive training that are geared towards a worst case scenario. You seem to dive based on the best case scenario. That's an excellent way of finding yourself behind the curve when things go south. It's absolutely the wrong attitude to have when approaching technical diving. If you want to do something a different way, and you think you can justify it to yourself, and subject matter experts give you their professional opinion that is contrary to yours, there's probably a good reason that it disagrees. This isn't a case of the world being flat, it isn't a case of "because that's how it's done," it's that we've pretty well figured out the best practices to safely dive. If you want to disagree with stuff like this, that's absolutely you're prerogative, but you should not espouse that information when it's been discounted by many people with much more training and experience. We're still making strides in areas like the most efficient decompression profiles, but the best way to send up an SMB has been figured out for a long time. Want to dive split fins and a stab jacket? Go right ahead. Want to espouse a lazy attitude towards shooting an SMB? Probably best to defer to the experts.

Here's how a separated SMB deployment should look when done properly. Notice how similarly the OP's video is to this video, even though this is a demonstration. The only modification you would do in a current is waiting to unfurl the SMB until after you had the spool attached, and "L" the line if required. In this case, since there's no current, there's no need for either.

 

[CWK]

BTW, in academic discourse (irrespective of whether it is between two professors or between a professor and an undergraduate), no professor would ever say that his credentials are better in order to further his position in the debate. This is the quickest way to being ridiculed within the academic community.

 

[gcarter]

Here's how a separated SMB deployment should look when done properly. Notice how similarly the OP's video is to this video, even though this is a demonstration. The only modification you would do in a current is waiting to unfurl the SMB until after you had the spool attached, and "L" the line if required. In this case, since there's no current, there's no need for either.

Why say it is OK to unfurl before attachment if you think a different sequence is required in current? KISS. There is zero requirement for this to be a different sequence in or out of current. I never unfurl my DSMB unless it is attached.

"L" the line not required? Maybe a lower risk of it getting tangled in yourself / valve etc. as it is not being swept towards you. But it is still very important to emphasize controlling the line which is what this is really about. Uncontrolled line hanging loose in no current can very easily cause an entanglement.

Other observations on the OP:

I never hold the spool like that with my fingers in the spool while deploying. Not a great practice. Easy to get a finger stuck, especially if wearing thick gloves.

When deploying, I will clip my boltsnap to the line rather than back to my BP/W. It helps to control the line as it unspools and keep it taut so it is less likely to tangle.

A good reason to hold in current while deploying: River drift diving to/from shore. You have navigated to your exit marker, and will need to go across current to the shore exit. Hold and deploy before continuing across current to shore. Drifting while deploying will affect your final exit.

 

[taimen]

taiman & compressor, you're missing the point of task loading during training on something like an SMB deployment.

No, I get the point very well. I still think that introducing task loading into repetitive training of skills by atrificially complicating them is not good. Especially when this leads to teaching a suboptimal configuration (DSMB separated).

Nobody dives with the spool separated. It's only for task loading during training.

Why then teach diving with spool separated. There must be better ways to add task loading than complicating basic maneuvers.

 

[Pearlman]

Then I asked wasn't I just told to plan my dive and dive my plan. If the only planned use for my spool is shooting DSMB, why shouldn't I prepare it according to my plan.

I always thought planning the dive and diving the plan referred to max depth, bottom time and choice of air etc. Further a plan for any contingency would include having to use the spool for other purposes correct? Especially for a tech. diver?

P

 

[taimen]

I always thought planning the dive and diving the plan referred to max depth, bottom time and choice of air etc.

Of course. But I tried to expand that mindset into configuration. Choice of carrying your DSMB attached (because it is its primary planned use) instead of separate (for unplanned purposes).
I think I already got the answer from this thread. Most of commenters admit diving DSMB and spool attached, even when they promote teaching doing it separately. I may end up diving it attached and maybe adding an extra spool for contingency. And I admit that practicing with added task loading is useful (I go to pool every week just to practice that. And if you have followed other threads, we practice underwater doff/don too... ).

 

[divinh]

I say that there is no need to iron out the DSMB because inflating it straightens it out naturally. You and all the agencies that you have done advanced training with may disagree with me. That is cool.

I say that the diver in the OPs initial video does not need to check her computer for her depth, bouyancy and trim because she is continually doing that with reference to the specific environment that she is in. You and all the agencies that you have done advanced training with may disagree with me. That is cool.

I think it was pointed out earlier in the thread that the plastic lining in the DSMB sometimes sticks to itself, which causes it to fail to inflate. The unrolling process could "exercise" the DSMB and remove the "kinks"? As a recreational diver, the DM/instructor is usually the one deploying the DSMB. I've yet to deploy a DSMB myself and I would probably unroll my DSMB first before inflating, just to make sure it will expand to full length as expected. I think the tendency is to always bring along a DSMB but not check it before every dive, like you would with other equipment.

Since the diver in the OP's initial video is practicing, I thought the depth checks were done because she might be deploying in the "blue" at some point, where there are no visual reference points. The depth checks are taught as part of the process so it becomes muscle memory, covering more general DSMB deployment scenarios.