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

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I recently unloaded an SMB I was dissatisfied with because no matter how I rolled it up, during dives if clipped off a D ring, maybe every 3rd dive or so, the roll would come unfurled by going out the side (the velcro strap around the roll didn't come loose, but it's like if you take the rolled up SMB and poke the roll in the side, making it come out the other side). The only solution was sticking it in my Dive Rite thigh pocket, which with reel took up enough space my space mask no longer fit comfortably in (which I like to carry when solo shore diving). I also found the finger spool wider and with more line than I likely need, since I'm unlikely to shoot it from much beyond safety stop depth. A friend admired it, though, so I gave it away to make room for getting one I want. With a BP/W setup, pocket space is an add-on function.

Some observations from a couple of days of checking into it:

1.) Good night, these things are expensive!

2.) If you dive regularly in places with swells, you might want a 6 foot wide rather than 4 foot narrow SMB, but the former are pretty big and can be a nuisance if you don't need that. I've got an old 6 footer I don't use.

3.) Finger spool (which I prefer) vs. wreck reel. I prefer the compactness of the former.

4.) I recently learned if the line snags during deployment the rising SMB can rip the spool right out of my hands.

5.) Not suggesting plagiarism, but I'd like link to Dive Gear Express's page (scroll way down) where they show that different features for inflation aren't common to every model. Not all inflate from the bottom, and of those that do, some are open and some semi-closed.

6.) An overpressure relief valve is your friend.

If I were clicking 'Buy' this minute, I'd get the DGX Gears Surface Marking Tube and also the small finger spool and all mesh lift bag sleeve (which looks made to attach to a backplate; don't know whether it'd attach so trimly to a jacket style BCD). After you look at the prices for competitor products, this looks like a really good deal that checks the boxes for semi-closed bottom inflation plus oral inflation option and an overpressure valve.

Which brings up another issue; how much dangling 'stuff' do you want hanging off you when you dive? If you were in horizontal trim in the water, how much stuff would hang down, and how far?
 
I recently unloaded an SMB I was dissatisfied with because no matter how I rolled it up, during dives if clipped off a D ring, maybe every 3rd dive or so, the roll would come unfurled by going out the side (the velcro strap around the roll didn't come loose, but it's like if you take the rolled up SMB and poke the roll in the side, making it come out the other side). The only solution was sticking it in my Dive Rite thigh pocket, which with reel took up enough space my space mask no longer fit comfortably in (which I like to carry when solo shore diving). I also found the finger spool wider and with more line than I likely need, since I'm unlikely to shoot it from much beyond safety stop depth. A friend admired it, though, so I gave it away to make room for getting one I want. With a BP/W setup, pocket space is an add-on function.

Some observations from a couple of days of checking into it:

1.) Good night, these things are expensive!
Tell me about it. I have like 10 of these things in different sizes/options
2.) If you dive regularly in places with swells, you might want a 6 foot wide rather than 4 foot narrow SMB, but the former are pretty big and can be a nuisance if you don't need that. I've got an old 6 footer I don't use.
Agreed, If it doesn't come with SOLAS tape, I'd put it on there (something addressed in the document already).
3.) Finger spool (which I prefer) vs. wreck reel. I prefer the compactness of the former.
Agreed.
4.) I recently learned if the line snags during deployment the rising SMB can rip the spool right out of my hands.
Yup. That's why putting fingers through is a bad idea.
5.) Not suggesting plagiarism, but I'd like link to Dive Gear Express's page (scroll way down) where they show that different features for inflation aren't common to every model. Not all inflate from the bottom, and of those that do, some are open and some semi-closed.
I'll include a link to that page. Very useful.
6.) An overpressure relief valve is your friend.
Absolutely. Though I've been told SMBs don't burst, just fizzle at the seams if the gas expands too much.
If I were clicking 'Buy' this minute, I'd get the DGX Gears Surface Marking Tube and also the small finger spool and all mesh lift bag sleeve (which looks made to attach to a backplate; don't know whether it'd attach so trimly to a jacket style BCD). After you look at the prices for competitor products, this looks like a really good deal that checks the boxes for semi-closed bottom inflation plus oral inflation option and an overpressure valve.
That looks like an excellent option. I like the SOLAS tape on top.
Which brings up another issue; how much dangling 'stuff' do you want hanging off you when you dive? If you were in horizontal trim in the water, how much stuff would hang down, and how far?
I use the butt D-ring to keep it out of my way.
 
I attach my dsmb to my butt d-ring too. It keeps it nicely out of the way, but still accessible. That mesh bag also looks really neat, but where would you mount it? At the bottom of the plate? I’d imagine getting the Velcro open back there would be tricky…
 
Also, that DGXgears stainless spool is gorgeous and I’m ordering one.
 
My response here is a bit late, but I'm having some trouble with this. If I understand correctly, a longer DSMB is straddled, correct? So for a not full DSMB, this is going to result in the lowest point (crotch) to have no gas, and some gas at both ends, only one of which has an OPV. As you dump gas from the front (I'm assuming you have this part of the DSMB in front of you), how are you to manage the expanding gas in the part of the DSMB that is behind your back?

Does my question make sense?
IMO, ascend slowly is really the best advice for this technique, because it will be clumsy and manual, and people are likely to not have practiced the technique much.

You may also have to deal with air-trapping from time-to-time. Dump valve is near your head for ease of access. If you are relatively neutral, you typically won't need much air in your DSMB, and if you're trimmed slightly up, you'll mostly be managing an air-bubble near the dump-valve. I'd say probably no gas in the area below the crotch ideally. Your trim won't be amazing, but this is a redundancy, not a shiny new product.

It may be worth emphasizing, that this method is a REDUNDANCY, but also clumsy and not a user-friendly BCD replacement. That way nobody is expecting it to be easy, but if your BCD blows a hole or hose gets ripped off, no need to panic or cramp yourself.

I do like describing both options; the shoot-to-surface and pull yourself up, and the poor-mans-BCD technique. Depending on the situation, one may be more applicable than the other. i.e. pulling yourself up isn't ideal for overhead environments.
 
IMO, ascend slowly is really the best advice for this technique, because it will be clumsy and manual, and people are likely to not have practiced the technique much.

You may also have to deal with air-trapping from time-to-time. Dump valve is near your head for ease of access. If you are relatively neutral, you typically won't need much air in your DSMB, and if you're trimmed slightly up, you'll mostly be managing an air-bubble near the dump-valve. I'd say probably no gas in the area below the crotch ideally. Your trim won't be amazing, but this is a redundancy, not a shiny new product.

It may be worth emphasizing, that this method is a REDUNDANCY, but also clumsy and not a user-friendly BCD replacement. That way nobody is expecting it to be easy, but if your BCD blows a hole or hose gets ripped off, no need to panic or cramp yourself.

I do like describing both options; the shoot-to-surface and pull yourself up, and the poor-mans-BCD technique. Depending on the situation, one may be more applicable than the other. i.e. pulling yourself up isn't ideal for overhead environments.
Okay, first, no requests for graphics design work. With the quality I demonstrate here, I'm much too busy:
1671211513622.png

I am not sure if my description was clear enough, so I created a photo quality, life-like image you see above.
How do you handle the expanding gas in the part of the DSMB that is behind your back/head?
 
Regarding the DSMB for redundant buoyancy, I would clip the bottom to the crotch ring and just pull/fold the top down. Ideally, clip the top to the crotch ring as well if there's a d-ring on that end. No, I'm not scared that it's attached to me (so is a wing after, all).

A better option in OW may be to just tip head up or down a bit (keeping the damaged end of the wing low), skip messing with the DSMB for buoyancy, and just ascend. Obviously, you need to know how to dump from either end of the wing, but you should know that anyway.
 
Regarding the DSMB for redundant buoyancy, I would clip the bottom to the crotch ring and just pull/fold the top down. Ideally, clip the top to the crotch ring as well if there's a d-ring on that end. No, I'm not scared that it's attached to me (so is a wing after, all).

A better option in OW may be to just tip head up or down a bit (keeping the damaged end of the wing low), skip messing with the DSMB for buoyancy, and just ascend. Obviously, you need to know how to dump from either end of the wing, but you should know that anyway.
So how tall of a DSMB are we talking about? While I'm 5'11", I'm not sure clipping off my crotch D-ring that I'm going to be able to reach the OPV string. Plus, that's going to be one thing in front of my face, obscuring my vision.

Doesn't sound like a good idea to me.
 
Guys, seriously.
Just shoot it to the surface and climb the rope.
A 2m dsmb has less than 10kg of lift btw, so don't expect to do it with a twinset and stages.
 
https://www.shearwater.com/products/perdix-ai/

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