DSMB line recovery technique

[divezonescuba]

A few years ago, I took an course from a world recognized instructor trainer. During the course, he utilized a technique that I had never seen before by a tec diver.

What he did was not recover the line during the ascent between deco stops. Once at the new deco stop, he recovered the line to the new deco stop. This process was repeated until the surface was reached. I do not think that this constituted an entanglement hazard as the line was always vertical due to the weight of the reel or the finger spool and bolt snap. It also served as a visual reference during the ascent for all the divers.

More recently, there was an online discussion of the technique that John Chatterton demonstrated in recovering a lost finger spool at the surface using a bolt snap or flashlight which I will call the weight recovery method.

I have been thinking about testing out these two concepts together in a blue water drift deco situation. Basically, once the DSMB is deployed from a given depth, say 70 feet or whatever, it is not recovered again until reaching the surface. It would not create an entanglement issue since it is hanging down vertically due to the weight of the reel or spool and boltsnap, provides a static visual reference, and lastly could be used in the event of a bouyancy issue (per PADI’s new course skill guidelines for the use of non-redundant bladders) during a blue water deco.

Once on the surface the weight recovery method is used to keep the line taught to prevent entanglement issues while recovering the finger spool or reel.

One aspect of one of the more publicized accidents may not have occurred if this was done when they lost bouyancy. It is my understanding that their lift bag that they deployed to assist with this problem failed when they lost tension on it. Of course that is only one of the many issues surrounding that accident.

So, I am curious if anyone has used this basic concept before?

I am sure someone will jump in to say that this is a equipment solution to a skills problem or a solution to a non-existent problem or I am going to kill a bunch of people if I test this. Go ahead if you need to do that to make yourself feel important.

 

[Edward3c]

When DSMBs were first introduced it was thought a reel or spool would be to slow, so the line was wound round a weight. When ready to deploy the weight would be dropped to extend the line, then the DSMB would be inflated and sent to the surface.

My first DSMB had 10m of line which was good for a 9m stop.

 

[Wibble]

Have used the big Halcyon SMB with a 60m/200’ Apeks finger spool for years. I like those as there a plenty of line and they’re easily stowed in drysuit pockets (always bring two SMBs on every dive). Really straightforward to deploy but there are quirks such as using caving techniques for clipping off.

Was diving in a wreck and dropped the spool as I arrived at the 6m/20’ stop with 30 mins to go. Idiot I said to myself. Without putting too much thought into it and very aware that the bottom was at 50m/180’ and did t want to loose the expensive Apeks spool, I started to wind the line around my left hand.

After a dozen turns it dawned on me that this was a stupid idea as I’ve effectively lost my hand. Worse I couldn’t simply slide it off as I’ll have a massive tangle of string all around me.... So I kept winding.

After an age the spool came into view and soon it was in my hand, but effectively tied to my SMB. Now what... I considered the predicament and ran through some options from cutting the line and shoving it in my pocket; clip a double ender weight on a loop and drop that down (halving the length); holding on to it until I get back on the boat... 25 mins to go, so no time pressure.

I started to unwind the line from my left hand on to the spool in my right. That is so damn awkward as it was not quite two turns of the spool to one turn off my left hand. It’s slow, it aches, it’s a right palaver. And it took 20 mins, so only about 5 mins of deco left


So what to do in the future? Definitely pull out a bight (loop) of string, clip on a double ender into the bight as a weight and work the string up from the spool side over to the bight side hauling the empty spool up whilst the double-ender drops down. Then wind the string back on the spool.

Or just opt for a nice chunky solid 125m/400’ Kent Tooling reel with a crack bottle SMB. Which I have now. I still keep one additional SMB on a small Custom Divers pocket reel in a pocket as a backup.

Spools are fine but they’re a total PITA if you drop them. Reels have ratchets. Big reels are massively easier to use than puny ones. And crack bottle or CO2 SMBs are almost essential in CCR.



Big heavy reels aid CCR decompression stops as I leave the reel dangling 2m/6’ below the stop, bouncing up and down to the waves on the surface. I like to deco out flat and neutrally buoyant either next to the line, or with the line running loosely through thumb and forefinger or even through a bolt snap. On CCR this means any fine adjustments to buoyancy can be done by slightly gripping on to the string, using the weight of the reel to pull me down or the buoyancy of the SMB to pull me up. No wasted diluent for buoyancy corrections.

The Kent Tooling reels make the Custom Diver reels look like toys! That explains why they’re so popular on UK dive boats.

 

[CuzzA]

I see no issue here. We use jugs with line to mark spots all the time. Sometimes we find them on the way back and ascend near the line, sometimes we don't and make free ascents. The only issues with diving around lines like this would be if you're on the wrong side and a boat snared the buoy and it crossed your body and entangled you or in a non existent current coupled with wave action the line can act a bit squirrely and even fin kicks can make it react and sometimes want to wrap around you. Not much of an issue if you get a wrap of line around you. Just clear it and back off a bit.

Frankly though, most guys I know just make blue water ascents, drifting deco and get picked up when they surface with no top side signaling device. But we don't have the currents in the Gulf of Mexico like some other regions, nor do we have such a small area that increases boat traffic to hazardous situations, so take that info with a grain of salt.

A final note though, just use a plastic spool instead of a fancy aluminum or stainless steel spool and the chances of losing it are significantly reduced.

That said, to answer your question. If I had an anchor weight style spool and lost it, I would just ascend the line and not worry about it. Pull it up in the comforts of the boat deck.

 

[Marie13]

Crack bottle SMBs don’t seem to exist in North America.

 

[tursiops]

Crack bottle SMBs don’t seem to exist in North America.

Crack Bottle DSMB - Incl. Crack Bottle Low Pressure Adapter DSMB from Kent Tooling Diving Products
AP Self-sealing SMB Marker Buoy with Inflation Cylinder

 

[Bierstadt]

Crack Bottle DSMB - Incl. Crack Bottle Low Pressure Adapter DSMB from Kent Tooling Diving Products
AP Self-sealing SMB Marker Buoy with Inflation Cylinder

Those look pretty neat, though the fact they are UK/EU shops does rather prove Marie's point. Makes sense for CCR diving.

 

[Wibble]

Oooh, learned something.

We use two types of "Self Inflating SMB" in the UK: using a 16 gram CO2 cylinder (these are used for inflating bicycle tires, etc). This tends to be a smaller SMB unless it uses two CO2 cylinders. Exceedingly easy to launch; unravel and a tug on the inflation toggle and it fills very fast. Slight challenge is make sure you're ready to launch it as once set off, that's it! Once you're back on the boat, make sure that you never pack away the blob with an empty CO2 cartridge.

The other self inflating SMB uses a small 0.1 litre "crack bottle" cylinder which is filled from a standard backgas cylinder (the crack bottle has either a yoke or DIN fitting to attach to the full cylinder). These SMBs are a bit larger, but inflate quite slowly (so don’t snatch out of your hand) and can be stopped as there's a valve on the crack bottle. Overall they're a little larger than the CO2 cylinder, too large to stow in suit pockets - tend to be on your reel. They do need more than 200 bar to fill the blob -- nobody likes a flaccid blob.


Surprised you don't have them in the western hemisphere.

 

[Coztick]

They're a little larger than the CO2 cylinder, but do need more than 200 bar to fill the blob

Seems a little excessive when you can orally inflate some or just capture your second stage exhaust to fill others.

 

[explore_DMC]

Personally, I would not want to intentionally leave my spool 50'+ below me, but in calm conditions I do not see it necessarily creating a problem.