I'm having trouble deploying DSMB...

[sea_ledford]

Why do you have a 16 foot long SMB is my question. Although I imagine @Wibble will say "Finally! A proper sized blob!"

I've used the 10 foot "monster" one from OMS and it was basically unmanageable with any sort of task loading. I can't imagine a 15 footer.

Unless you are launching from deeper than 100 feet or so, the only way you'll get a decent loft out of that will be from a reg. At 6 times the volume of a standard SMB, a full lungfull won't do anything, even if launching from 100 feet.

150 lbs lift = 2.3 cuft of volume at the surface
From 4ata you would have to add 0.78 cuft for it to be full at the surface
That's still 50 lbs of lift at depth.
If your reg flows at 150cuft/min, you are looking at a full purge for 2 seconds to get it 1/3 full at 100 feet.

6 liters is about normal for an adult male lung volume. That's only 0.2 cuft.

Get a smaller DSMB or just fill it at the surface.

 

[RyanT]

Why do you have a 16 foot long SMB is my question.

Agreed. Seriously, I don't think I've actually ever seen one that size for sale. My bag is 7'; it's big by most standards. I don't have any trouble managing it. But it is big; I can see where many folks would find it a bit unwieldy. A bigger bag would likely be unmanageable by the average diver. Anything bigger is completely unnecessary.

 

[rob.mwpropane]

So, I've recently purchased a DSMB but I could never fully inflate it in water. I know I only need to get halfway full but even then I could not get it. So the DSMB was always flat on the surface and it is very very annoying. I tried the open end, using the LP hose but none of those works. The DSMB always brings me up before I can get halfway full. This DSMB has 130lbs of the lift so whatever I do I couldn't pull on it long enough until it gets inflated. Note: This DSMB is 3 times longer than a Halcyon and 6 times larger in volumes.

View attachment 706585 View attachment 706586

Maybe trying to compensate for something?

 

[johndiver999]

The utility of something that large is questionable. What I suspect that some people fail to realize is that unless it is super rough and windy, you really don't need a huge tall smb.

IF it IS rough, very windy, there will be white caps and waves and having a really tall smb would be great.... but it can't work. The wind will fold it over and bend it in half.

Deploy it from 100 plus feet, the air should expand and even if it hits the surface half full it is going to provide decent visibility. Trying to put a lot of air into an smb at depth is dangerous. If you get anything caught on it, you are going for a ride and it might be your last one.

 

[alanchang]

At What depth are you trying to deploy?

10 meters

 

[FishWatcher747]

There was a recent discussion about DSMBs that was informative to me. For Cozumel drift diving with potentially a lot of boats around, unless you always surface with your guide (who deploys his DSMB) being able to use a DSMB is pretty important.

My second trip to Coz I deployed a 2 meter, 15 lb DSMB orally and it would lay flat on the surface and not be fully inflated. Some of the regular Coz divers on the boat had 40 inch fairly skinny sausages with 5 lbs of lift which would fully inflate orally and be impressively visible on the surface.

My 3rd trip to Coz I used a 40 inch one with excellent results.

A dive captain commented in the discussion that he would carry two DSMBs, the small one for deploying underwater and a large one for deploying on the surface in case the boat was not visible to pick you up when you surfaced.

That thing you have is better for surface deployment.

Edit. If you really think you need that large of a DSMB you might want to get a Personal Locator Beacon.

 

[alanchang]

I think a better question is why you are trying to fully inflate a 16' smb from depth?
Which closely aligns with my next question of why would you buy a 16' smb?

I wanted to fully inflate a 16ft dsmb because I want it to stay up on the surface and I don't want it lying on the water surface.

I purchased a 16ft dsmb because I don't want to get hit by a boat, I want people to see me 100% and want to make sure no one on the boat has a larger dsmb than I do.

 

[alanchang]

For me, this type of a very long DSMB' are for use on surface to signal dive boats or rescue teams to know where you are from distance after you inflate them ON the SURFACE not from depth. For true DSMB launched from depth, I'd use a much short DSMB, 1.4 - 1.8m, at the most.

But this 16ft dsmb has an open bottom just like the shorter ones and it seems like it's meant to be deployed in water from depth.

 

[Robert H. Diver]

10 meters

Idk man, try a smaller one.

 

[Manatee Diver]

Go deeper. You should already know the math, you need to put 65lbs of air into that thing to inflate it at 10 meters. Of course you are going to shoot up like a rocket. Go for it at 30 meters and it is a slightly more manageable amount of air you need to add.