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D or no D?

The “D” stands for ‘delayed’, and it’s ALWAYS better to wait until the end to pop that sausage.

Wait... what?!?

Sorry for the catfishing there, but this is about your SMB, or Surface Marker Buoy, and what you’ve actually been diving with, which has a giant D in front of it. 

There’s some terminological brain constipation in the dive industry  regarding two very different pieces of equipment: an SMB, and a DSMB.

What makes it an SMB?

A Surface Marker Buoy, abbreviated as an SMB, is quite simply something that an underwater person (human or mermaid) deploys at the surface PRIOR to their decent and tows along with them. This alerts ordinary surface dwellers to their underwater presence. It does NOT indicate eminent surfacing or emergency – in fact, nothing does. There are no color specific requirements or communication tips for delineating between “look out, I’m down here” and “send help, I’m out of snacks”.

Where does the 'D' come from?

Let’s keep this PG folks. And that includes your brain!

The D in DSMB refers to the timing of deployment. Typically inflated and released while still underwater (an exceptional Divemaster skill to master, by the way), the SMB hits the surface BEFORE the underwater party, but also AFTER the start of the session. It is delayed!

But, can’t you also deploy it in an emergency once you’ve surfaced as a signaling device? Abso-SMB-lutely!! Doesn’t change it from a DSMB to an SMB, you just took the D out of its use.

Is deployment the only difference?

The short answer is yes. The more robust answer is no. 

A DMSB is typically going to have more than one method of inflation. A well designed D-SMB is going to allow for oral or low pressure inflator fill, but will also include a heat sealed opening at the bottom which permits gas to be exhaled or blasted from a free second stage up into the buoy. 

Also, consider the markings. An SMB will usually have the words “Diver Below” which can be easily seen on the surface. 

Conversely, the D-SMB is just a brightly colored inflatable sock that has a brand name on it. You’re typically using this to alert your boat to come and pick you up after your dive. 

Then there’s the lift to consider. Most people aren’t using a SMB to “hang” off of, and so these are usually smaller notification devices. A DSMB, on the other hand, can be up to 8″ in diameter and over six feet in length, offering up to 50# of lift. This can come in particularly handy when you are forced to pull a rando decompression stop on a missed up-line. 

At the end of the day...

… the ‘D’ is just about how you use it. Sure, there are all sorts of things to consider when deploying your sausage (yes, they are called “safety sausages”) like length and girth, purge valves, and inflation methods. But you might also consider color as an option and discuss amongst your team what pink means as compared to yellow, orange, or even yellow/orange and carry multiple DSMB on your lengthy trip into the abyss!

I’m sure you have your own opinions, and I’d love to hear them! Do you dive a D or not? And why did you call it that. 

Just an FYI, I named mine Grover. 😈

Until next time, train hard and dive easy!

Dr Eric "Doc" Strand

After being injured in the line of duty while serving in the Marines, SSGT Strand transitioned to Dr. Strand, and spent the next 25 years practicing medicine, dedicating his time and energy to bringing better health and enlightenment to the community he served. After learning to dive with his family, he quickly felt a growing passion for the underwater world: the peace and tranquility was greater than any form of meditation he'd ever tried. SCUBA diving became the hobby at first, then moved slowly into the next, and hopefully last profession. A published author and poet, Doc's passion for creativity coupled with his experiences and travels abroad impact not only his writing style, but also his passion for life, teaching, SCUBA diving, and medicine.

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