DSMB’s, or Delayed Surface Marker Buoys, are a diver’s best friend. Used for communication with surface crews or boats while the diver is still at depth.
They can be used to signal the need for a boat pick up, as a distress signal, a marker of a location (maybe of that sunken treasure you found?), or to indicate the need for additional air on long decompression stops.
Basically, they are tubular buoys made out of PVC or similar materials, and attached to a line reel or spool. They are typically orange, red, or yellow, sometimes with various colors used to communicate various messages.
At many dive spots you’ll see them vary in colors and manly be used to signal for passing boats, before divers accent.
It’s one of those safety items commonly used, and often required, during boat or drift dives, where they are used to signal a diver’s or dive team’s position as they surface, and are typically launched during the safety stop.
Launching one can be a bit tricky, though, as they influence your buoyancy, but also due to the risk of getting tangled up in the line and getting pulled to the surface by the DSMB. This guide will teach you the basic steps to launching a DSMB safely.
SETUP OF A DSMB
First things first, setting up your DSMB.
Here you have to main options.
- Attach your DSMB to a spool.
- Attach your DSMB to a reel.
Using a spool or a reel both have pro’s and cons:
The spool is lighter and smaller, meaning the whole setup takes up less space in your configuration. Second, a line reel will have some form of locking mechanism that can potentially jam, sending you the surface if it jams as you launch the DSMB.
The reel provides a more stable platform to launch your DSMB, it is easier to wind as you make your ascent but does require a lot more space to store. As above most reels have some form of locking mechanism which is great for stops but can, in some cases catch as you deploy the DSMB if you are not paying attention.
DEPLOYMENT DURING SCUBA DIVING
When it comes time to launch it, here’s a step-by-step guide:
- As DSMB’s are often launched during safety stops, that means you most likely need to launch it mid-water, so make sure your buoyancy skills are up to spec. When it’s time to launch, find your perfect hover point, and expel a small amount of air making yourself just a tad negative in the water.
- Take out the DSMB and unpack it, taking care not to drop the reel. As it has no lock it will run out its full length of line before stopping, which will be a mess to coil up again once you’re out of the water.
- Holding the DSMB and line spool / reel in your left hand, use your right hand to pull open the bottom of the DSMB.
- Tilt your head slight, bringing one of your regulator exhaust valves close to the opening of the DSMB, taking care not to get the line entangled with your regulator or regulator hose.
- Take a moderately deep breath, hold the opening of the DSMB over the valve, and exhale. Your exhalation gas will run from the exhaust valve and into the DSMB.
- Repeat this once or twice as needed, until you feel a strong tug from the DSMB (use your breathing to counter the positive buoyancy of the DSMB or release a small amount of air from your BSC), then release it, holding the line spool / reel in your right or left hand and allow it to un-reel line as needed.
Once the DSMB breaks the surface, reel in a bit of line so it is taught and the DSMB stands straight up on the surface, making it as tall and visible as possible.
Remember to check your depth and dive computer from time to time. Rather take a minute longer deploying your DSMB than you accidentally pop to the surface.
There are of course DSMB’s on the market that has a crack bottle fitted, such as the DSMBCi from AP valves. This requires no tilting of the head, keeps the line away from you regulator. It does make for an easier deployment but comes at a price.
TRAINING IN THE DEPLOYING
Many agencies now provide a DSMB training course. These courses take you through the whole DSMB process and give you a safe environment to practice deploying your DSMB.
Many divers will tell you to use your alternate second stage to fill the DSMB, but there are several advantages to the method described above, where you use your exhalation air instead.
First, filling air into a DSMB makes it positively buoyant. By using your exhaled air, there’s no shift on your overall buoyancy. Second, this method allows you to fill your DSMB even if you’re diving with a technical setup, where your secondary second stage is stored in a necklace around your neck.
Practice makes perfect, of course, so make sure you practice this before needing to do it for real, and keep practicing from time to time to keep your skills honed.
A pool or a local dive site is perfect for this. But make sure to let any shore based bystanders know that you’re only training, so they don’t misinterpret it as a distress signal and start calling the coast guard.
Yes! Your reel, line spool and DSMB do need some basic maintenance to make sure that you have years of hassle free operation.
On every weekend diving there is always someone that has a problem with their reel. Line snagging, reel jamming and so on.
My question is always ‘when was the last time you serviced you reel & line?’.
The answer, 99% of the time is ‘service?’.
- There are a few quick and simple steps that you can do that will prolong the life of your reel and line. It will help to prevent reel jams and line tangles.
- Pop your reel into a fresh bucket of water, leave it over night.
- Reel out the line completely, you can do this in a number of ways, I put mine around patio furniture. This help you to check the quality and the state of the line (abrasions, rotting etc).
- While you have the line completely off take the opportunity to grease, tighten and clean the reel itself.
- When it is all dry wind on the line taking your time to make sure the line is evenly spread and suitably tight.
It’s not rocket science but it really will help with all those niggles!
Information source: DiveStyle Diving limited and Dive-In Magazine