DAN DSMB - where's the manual?

[wetb4igetinthewater]

Why in gods name did they not go for Hellenic Archaeological Dive Exploration Society? The missed opportunity is astounding!

That's awesome! Considering I came up with HAES, I screwed up.

But given that I'll be reaching out to the Greek community through the churches, I don't see many priests being happy with me asking "Would you like to make a contribution to HADES?" Lololol

 

[BlueTrin]

As on the video that @Jim Lapenta shared above, a DSMB is intended to be shot from depth. You put a small amount of air in it, and as it shoots to the surface, the air expands inflating it more.

If you put three big breaths in a DSMB at depth, you will need to adjust your buoyancy to compensate. And then as soon as you let it go, you will need to re-compensate. Usually one breath in a small DSMB at your safety stop is enough to get to expand to full by the time it hits the surface.

For a large DSMB, I'll try to launch it at 10m, which will allow for more expansion by the time it hits the surface. Once I've surfaced, if the swell is big I might fully inflate it and hang off it to make it more visible for the boat.

If you use a very thick 6ft DSMB unless you launch it fro very deep you may have to do multiple breaths (actually for the really large ones you will probably need multiple breaths).

If you want to inflate orally, you put a breath in, put back your reg in your mouth, then dump a bit of air from your BCD before to breath from your reg.

Another technique is to fin a bit downwards while doing it.

If your DSMB can be connected to a LP connector, then you can just inflate it using that and let is go. You can fin a bit downwards while doing it if you really want it to get it fully inflated and you are not deep enough.

Just make sure you hold the DSMB and spool/reel in one hand (I use the left hand), the second finger can be put around the DSMB inflator so that you can let it go by opening the second finger. That leaves the right hand to manipulate the LP hose/dump air if needed.

 

[wetb4igetinthewater]

I really don't like the multiple breaths practice for open ocean diving. Mark your DSMB at 1/4 from the top for 100 feet / 30 meters, 1/3 for 66 feet / 20 meters and 1/2 for 33 feet / 10 meters. Figure out need you need to be to sufficiently orally inflate.

Or transfer gas from your BCD/wing. This method of inflation takes more practice.

I recommend against compensating for changes in buoyancy when inflating a DSMB. Sure lots (most?) people do it, but I prefer other options.

 

[SlugLife]

I really don't like the multiple breaths practice for open ocean diving. Mark your DSMB at 1/4 from the top for 100 feet / 30 meters, 1/3 for 66 feet / 20 meters and 1/2 for 33 feet / 10 meters. Figure out need you need to be to sufficiently orally inflate.

Or transfer gas from your BCD/wing. This method of inflation takes more practice.

I recommend against compensating for changes in buoyancy when inflating a DSMB. Sure lots (most?) people do it, but I prefer other options.

Nice! I don't know why I didn't think of that sooner. I've never been trained to use a DSMB, just watched a couple videos and went on my way. That makes total sense, and I think I'll mark my DSMB now.

 

[sea_ledford]

Water trapping is the main reason I don't like the one way valve at the bottom of most lift bags and SMBs. The easiest way to get it out is to unscrew the pull dump and dump out the water (and it looks like the DAN one is TINY). You can also roll it up toward the pull dump and just pull the toggle to dump out the water, but it takes more effort and you'll still have water left in there. Either way pretty much has to be done out of the water though.

I prefer open bottom dsmbs, but I know I'm in the minority there. I'll cut out the one way valve in lift bags, having then in there make no sense at all.

 

[wetb4igetinthewater]

Nice! I don't know why I didn't think of that sooner. I've never been trained to use a DSMB, just watched a couple videos and went on my way. That makes total sense, and I think I'll mark my DSMB now.

I read about it somewhere here on SB. It is going into the blog post I'll submit to SDI.

Water trapping is the main reason I don't like the one way valve at the bottom of most lift bags and SMBs. The easiest way to get it out is to unscrew the pull dump and dump out the water (and it looks like the DAN one is TINY). You can also roll it up toward the pull dump and just pull the toggle to dump out the water, but it takes more effort and you'll still have water left in there. Either way pretty much has to be done out of the water though.

I prefer open bottom dsmbs, but I know I'm in the minority there. I'll cut out the one way valve in lift bags, having then in there make no sense at all.

You can still orally inflate those and maintain constant buoyancy

 

[johndiver999]

Water trapping is the main reason I don't like the one way valve at the bottom of most lift bags and SMBs. The easiest way to get it out is to unscrew the pull dump and dump out the water (and it looks like the DAN one is TINY). You can also roll it up toward the pull dump and just pull the toggle to dump out the water, but it takes more effort and you'll still have water left in there. Either way pretty much has to be done out of the water though.

I prefer open bottom dsmbs, but I know I'm in the minority there. I'll cut out the one way valve in lift bags, having then in there make no sense at all.

I thought the one way flap on a lift bag would be useful when the bag hops out of the water on ascent and then might loose some air and sink back down? The valve should prevent that.

 

[SlugLife]

I thought the one way flap on a lift bag would be useful when the bag hops out of the water on ascent and then might loose some air and sink back down? The valve should prevent that.

That's the general idea, to prevent air-loss when the bottom of the DSMB exits the water for any reason, or is not vertical. The "jump out of water" loss should be somewhat minimal, but you'll lose air if it "lays down" for any reason.

Which brings up two bonus uses of a DSMB:

• Surface Flotation - The DSMB can act like a "pool noodle" on the surface. This is useful during a BCD failure, or if you have to wait for a rescue. For example, you may find your BCD likes to face-plant you into the water with no finning, or is uncomfortable for long periods of time.
• Redundant Buoyancy Control - If your BCD fails during a dive, you can use a DSMB somewhat like a BCD by adding air and deploying it underneath you. Dump air from the over-pressure valve as you ascend.

You could still probably do the same with an open-bottom SMB, but it would be even more challenging.

 

[sea_ledford]

I thought the one way flap on a lift bag would be useful when the bag hops out of the water on ascent and then might loose some air and sink back down? The valve should prevent that.

That's the theory. I've never had a bag come far enough out of the water for it to be a problem though. But I also am more likely to use a lift bag to lift or drop something under control, not send it rocketing to the surface on it's own. If I was doing that with heavy items, I might thing a closed bag would be preferable. RIght tool for the right job.

 

[wetb4igetinthewater]

That's the general idea, to prevent air-loss when the bottom of the DSMB exits the water for any reason, or is not vertical. The "jump out of water" loss should be somewhat minimal, but you'll lose air if it "lays down" for any reason.

Which brings up two bonus uses of a DSMB:

• Surface Flotation - The DSMB can act like a "pool noodle" on the surface. This is useful during a BCD failure, or if you have to wait for a rescue. For example, you may find your BCD likes to face-plant you into the water with no finning, or is uncomfortable for long periods of time.
• Redundant Buoyancy Control - If your BCD fails during a dive, you can use a DSMB somewhat like a BCD by adding air and deploying it underneath you. Dump air from the over-pressure valve as you ascend.

You reading my mind? Some of my recent additions to my doc.