I need your help. DSMBs, what are people's questions/concerns/etc.?

[wetb4igetinthewater]

So my DSMB document/manual/whatever, has been discussed in different threads where people said they wanted a copy. While cruising old DMs, I came across one conversation (name blacked out for privacy reasons) from a seasoned instructor that was even interested in paying for this information that has made me realized how deficient training/materials might actually be. I don't have the materials for all agencies on DSMB deployment, so I can't speak to how universal this is a problem.

Now I'm not interested in the piddly income that selling this material would bring. If it was about money, I'd be better off with a second job at McDonald's as the income divided by number of hours put into it is going to be far less than minimum wage. My preference for the sake of reach/distribution is a blog post/series (depends on how long it gets and SDI's final decision as it is their blog, not mine).

As I'm not an educator, my importance is probably less than that of a cockroach, but I'd still like to request from you, the new diver, the experienced diver, the instructor, what questions/concerns do you have that you'd like addressed? What format would you prefer? You are the ones I'm trying to serve here.

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[Rob9876]

Here's one: DSMB's are listed as redundant buoyancy in SDI Solo. It would be nice to know an approximate lift capability for normal 4' and 6' DSMBs, as some weight ditching might be necessary (I know, it shouldn't be if properly weighted, but many aren't) and it would be good to know approximately how much lift the DSMBs generate.

Related question: I believe SDI Solo suggests releasing the DSMB and reeling yourself up. Not actually super easy to do when I practiced in a quarry (with all air out of BCD at depth). I'm wondering if partially inflating and keeping the DSMB in hand would make any sense?

 

[lowwall]

I have no idea what's in your manual, but IMO this is a subject that's best addressed by demonstrations. I suggest a YouTube video or videos with a link in the notes to your written material.

 

[wetb4igetinthewater]

Here's one: DSMB's are listed as redundant buoyancy in SDI Solo. It would be nice to know an approximate lift capability for normal 4' and 6' DSMBs, as some weight ditching might be necessary (I know, it shouldn't be if properly weighted, but many aren't) and it would be good to know approximately how much lift the DSMBs generate.

Now that's an interesting idea. I could do this with a fish scale underwater that is anchored on the bottom. That would be incredibly helpful. Thank you for this helpful tip.

Related question: I believe SDI Solo suggests releasing the DSMB and reeling yourself up. Not actually super easy to do when I practiced in a quarry (with all air out of BCD at depth). I'm wondering if partially inflating and keeping the DSMB in hand would make any sense?

Are you talking about using the DSMB to ascend? The one problem I have with that is that as the gas expands, it will displace more water and become more buoyant. You need then to dump gas from it. Does this make sense? Am I understanding your statement correctly?

EDIT: what is the issue you are facing while reeling yourself up? Are you using a spool or reel? If the former, are you using a boltsnap to reel in the line?

I have no idea what's in your manual, but IMO this is a subject that's best addressed by demonstrations. I suggest a YouTube video or videos with a link in the notes to your written material.

Absolutely. Something I'm planning on doing eventually, but not in the near term. Though as video shows all flaws, it is going to likely take a few takes. I had a conversation with Trace about demonstration videos he told me he could pick up on some little mistake in each one. Given the close, personal friendships I've made with a few people, can you imagine the comments I'd get for anything short of perfection? I'll still do it, but not post here, but other social media outlets.

 

[L13]

Related question: I believe SDI Solo suggests releasing the DSMB and reeling yourself up. Not actually super easy to do when I practiced in a quarry (with all air out of BCD at depth). I'm wondering if partially inflating and keeping the DSMB in hand would make any sense?

I believe the idea is that a controlled ascent with a DSMB as BC would be difficult. you would have to vent air on the way up, and if you ever overshot on venting, add air. If the DSMB is full on the surface, you have complete control of your ascent rate while reeling yourself up.

 

[mattfish]

I have seen a few great (and inspiring) videos of deploying a DSMB, but I haven't seen anything showing the small details. Like how do you wrap the cord around the boltsnap when wearing the set, and how do you wrap it once the MB is deployed? How do you reel-in a spool with a boltsnap like a handle? What is a good look or feel for a buoy to know when you've added enough air to deploy it?

I have my own answers to a few of those questions, but I'm not sure they are the best. A writeup with pictures or a series of close-up shot videos showing those sorts of details would be awesome for me (and hopefully others).

 

[Rob9876]

Yes, I understand the idea of reeling up, but not so easy if you actually try it. For me, emptying all air out of BCD, in a quarry where I have a 5mm suit and boots with a 3mm vest and a decent bit of lead to get down (I'm a big guy). I'm using a thumb spool -- reel would likely be easier, but realistically I never carry a reel.

Yes, I understand gas expanding as one ascends -- part of why I mentioned perhaps inflating the DSMB only partially. I wonder if doing that to initiate an ascent, then being ready to release (or inflate more and release) then switch to reeling up might be an option.

Again, I understand the suggested method, I just found it a bit difficult to reel myself up on a finger spool with "quarry level" neoprene and lead. To be fair, in trying this I was mainly trying to see the lift from the DSMB, so I was not finning as I likely would in an emergency situation. I've only tried it this way once so far -- started on my back on a training platform at 30 feet.

EDIT: This is why I was curious about lift -- wondering if in an emergency situation I might need to ditch at least some weight to reel up (again I understand that if perfectly weighted that's probably not needed).

 

[NothingClever]

I think laying parallel on top of one’s DSMB with inflator valve in one hand for positive control and the other hand free to burp the OPV toggle is a better technique for using a DSMB as redundant buoyancy.

A longer DSMB has the advantage of being long enough for the upper end of the DSMB to pass under the groin and extend up a little bit. Make sure to squeeze some air into that end. This helps keep the DSMB properly positioned.

Laying across it like a pool noodle seems like a bad idea.

 

[wetb4igetinthewater]

I have seen a few great (and inspiring) videos of deploying a DSMB, but I haven't seen anything showing the small details. Like how do you wrap the cord around the boltsnap when wearing the set, and how do you wrap it once the DSMB is deployed?

I'm sorry, but I am not understanding this question. I edited your comment here as I think you missed a couple letters. Please correct me if I was wrong to do so.

How do you reel-in a spool with a boltsnap like a handle?

Good question. I hope pictures of doing so will translate. A video for sure will help.

What is a good look or feel for a buoy to know when you've added enough air to deploy it?

We all agree that a DSMB should be full at the surface. I stole the idea of marking a DSMB for various depths that correspond to atmospheric pressure: so 1/2 from the top would be 10 m/33 ft, 2/3 from the top would be 20 m/66 ft, 1/4 from the top 30 m/100 feet

I have my own answers to a few of those questions, but I'm not sure they are the best. A writeup with pictures or a series of close-up shot videos showing those sorts of details would be awesome for me (and hopefully others).

I'd love to hear them. Your ideas may be better than my own and/or yours help me fine tune/use better language.

 

[Vicko]

In a emergency situation you may as well swim yourself up, but I do love using large dsmb-s to do deco, let's me sleep trough the 6m stop.
Reeling yourself up sounds less than practical, if you are using it for emergency ascents, just climb the rope and leave the reel dangling, you can always recover it on the surface.

Can this document be viewed somewhere, I actually hate demonstrating dsmb deployments in shallow water, I usually pop my bellow 20m just for the convenience of only one breath to inflate.