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

[sea_ledford]

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.

If you try to do a partial inflate, and basically use it as an external BC, I would think the task loading of keeping it at the proper lift would be a challenge. Keep in mind you would be doing this in a situation of full loss of buoyancy, and significantly over-weighted for the current depth (otherwise you wouldn't need to do it in the first place), possibly having broken your planned max depth, potentially by a lot, depending on the dive site and how quick you are, and possibly in deco. Adding complexity would be the last thing I would want to do.

Launch that sucker to the surface and reel yourself up. It may not be easy to do, but it'll be simple.

 

[lowwall]

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.

I used a reel (attached to a float, not a DSMB) for the first time 2 weeks ago off Boynton Beach. It was a boat dive and my buddy and I were under one float with with an instructor and student. The student got low on air, so the instructor handed me the reel and went up (under her own DSMB).

When it was our time to ascend, I did reel myself up. I was only a couple of pounds negative even with an empty wing so it was pretty easy and kind of fun. I did kick up a few times to ease the minimal strain of reeling. I think if you had a lot of excess weight, you'd want to kick while reeling. You could hang if you needed a break.

 

[Rob9876]

Has anyone here actually done it with full colder water neoprene and weights, at depth? The textbook answer is clear, but I'd be curious to hear from those who have done it.

With my cold (56F) water neoprene and weights it was quite difficult, and I could not just hang -- I started falling back down, floundering around on the slick platform. Finning would have helped, but curious about lift in case of cramping or other problem. Might be necessary to ditch some fraction of weight.

 

[wetb4igetinthewater]

Has anyone here actually done it with full colder water neoprene and weights, at depth? The textbook answer is clear, but I'd be curious to hear from those who have done it.

Yes, if you mean neoprene dry suit. Haven't done it in a wetsuit. As I have stated many times, I'm a wimp when it comes to temperature. I did my open water in June, lucked out with nice sunny weather that prevented me from getting too cold. I went straight to a neoprene dry suit that I bought off Craigslist that I started using without a class (and I lived to tell this tale, though maybe I'm dead. Death is like stupidity. You don't know if you are dead, but everyone else does).

With my cold (56F) water neoprene and weights it was quite difficult, and I could not just hang -- I started falling back down, floundering around on the slick platform. Finning would have helped, but curious about lift in case of cramping or other problem. Might be necessary to ditch some fraction of weight.

Cold? That's warm for the Puget Sound!

Let me ask you this about weighting. Do you have just enough weight to be able to maintain your safety stop with a nearly empty cylinder AND handle the remaining ascent with your expanding neoprene wetsuit (I'm assuming here)?

Are you familiar with the balanced rig concept?

 

[wetb4igetinthewater]

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,

Not yet

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.

I have small DSMBs for teaching in confined water. If a student were ever to say "well, standards allow an SMB to be inflated from the surface", I'd toss them my 5 meter/16 foot DSMB and say "Here you go!" (kidding)

 

[Rob9876]

Let me ask you this about weighting. Do you have just enough weight to be able to maintain your safety stop with a nearly empty cylinder AND handle the remaining ascent with your expanding neoprene wetsuit (I'm assuming here)?

Are you familiar with the balanced rig concept?

I'm definitely familiar with the balanced rig concept. I'm also often overweighted -- especially in cold water. Here's are a few reasons why: (1) my body weight tends to go up and down, changing the amount of weight I need (wish it didn't, but that's reality); (2) my dives tend to alternate willy nilly between warm saltwater to cold (for me) thermoclines in freshwater quarries, so I'm often not in the same conditions, same kit, etc. consistently to fully dial in my weighting; (3) sometimes diving with newer divers I like to have a little extra weight in case I need to help them hold a safety stop also. Ultimately, I don't think I'm usually too far off from optimal weighting, but I do err on this side of overweighting for reasons stated to avoid popping up.

 

[wetb4igetinthewater]

I'm definitely familiar with the balanced rig concept. I'm also often overweighted -- especially in cold water. Here's are a few reasons why: (1) my body weight tends to go up and down, changing the amount of weight I need (wish it didn't, but that's reality); (2) my dives tend to alternate willy nilly between warm saltwater to cold (for me) thermoclines in freshwater quarries, so I'm often not in the same conditions, same kit, etc. consistently to fully dial in my weighting; (3) sometimes diving with newer divers I like to have a little extra weight in case I need to help them hold a safety stop also. Ultimately, I don't think I'm usually too far off from optimal weighting, but I do err on this side of overweighting for reasons stated to avoid popping up.

Got it. I'm just a bit concerned by your comment of

With my cold (56F) water neoprene and weights it was quite difficult, and I could not just hang -- I started falling back down, floundering around on the slick platform. Finning would have helped, but curious about lift in case of cramping or other problem. Might be necessary to ditch some fraction of weight.

where it seems that your weighting is rather excessive. It shouldn't (and should is a dangerous word. I should not have to pay so much in taxes.....) be that difficult to ascend. You should pretty much always be close to neutral, so a kick cycle should get you ascending (to which you need to dump gas to control your ascent rate).

Am I way off the mark for your situation?

 

[Bazzathemammoth]

Great idea. Maybe an unbiased list of different ways to use them with pros/cons would be a great starting point. Eg: oral inflate from depth vs octy inflate at safety stop.

I was aware of using it as redundant buoyancy, but never thought about shooting it then reeling myself up. Thanks for the tip

 

[wetb4igetinthewater]

Great idea. Maybe an unbiased list of different ways to use them with pros/cons would be a great starting point. Eg: oral inflate from depth vs octy inflate at safety stop.

I was aware of using it as redundant buoyancy, but never thought about shooting it then reeling myself up. Thanks for the tip

This has been a great discussion and has exceeded my expectations. Thank you all for participating.

 

[Rob9876]

Got it. I'm just a bit concerned by your comment of

where it seems that your weighting is rather excessive. It shouldn't (and should is a dangerous word. I should not have to pay so much in taxes.....) be that difficult to ascend. You should pretty much always be close to neutral, so a kick cycle should get you ascending (to which you need to dump gas to control your ascent rate).

Am I way off the mark for your situation?

Honestly I don't think that I was really that much overweighted for being in 8/5 neoprene (wetsuit+vest) diving AL80. As mentioned, for this drill I was not really kicking or pushing off from the platform, as I wanted to see how it would be if cramped or otherwise unable to kick and just had to rely on reeling myself up. Hopefully that is unlikely, and when things warm up (around June for quarries near me) I'll probably try it again and allow myself to kick and/or push off. Hopefully that will be better than just trying to reel myself up.