In your initial dive-training course, you might have been taught how to inflate a surface marker buoy (SMB) on the surface. For those who don’t remember, a SMB is an inflatable buoy, attached to a line, and used by divers to let their boat know their position while still underwater. Even though inflating one may not seem like a skill you’ll need to use early in your diving career, it absolutely could be, so it’s important to know what to do.
Commonly known as a safety sausage, this device takes up only a small amount of space in your luggage, and then in your BCD pocket or clipped to your jacket. It can be crucial when it comes to your safety. Some are designed to be deployed from underwater, and are known as Delayed Surface Marker Buoys (DSMB). These are typically used at the end of drift dives in order to signal to the boat where you are, or in areas with boat traffic to make sure you are coming up safely.
Deploying one underwater will take a bit of practice. Reels or lines may vary from basic to advanced systems, and may vary in length from 16 to 328 feet (5 to 100 m). Before buying a reel or a line, ask around and see what your dive buddies use and why they like it. Don’t forget that the inflatable tube itself is a signaling device, so it should be big and bright enough that a boat could spot it from a distance. Some SMBs will be semi-closed and have a dump valve; some of them will require oral inflation. These small features can make a difference, so make sure to try your equipment on dry land before you take it diving, and also practice deploying it as often as you can with assistance from a dive buddy or your dive guide if necessary.
When deploying a marker from underwater, the air you put into it will change your buoyancy, so you want to be able to control your position in the water during the DSMB launch. Make sure that neither you nor another diver gets entangled in your line.
Deploying a marker on the surface is quite easy: you just use your mouth or your regulator to blow air inside it, and you’re all set. Despite this, be sure to practice, as rough surface conditions will hamper your efforts, and you don’t want this to be the first time you’ve deployed your buoy.
Recreational divers may think carrying an SMB is pointless since your dive guide is most likely carrying one or you are diving in an area that you know, but sometimes dives do not go exactly as planned. What if the current picks up and you drift further away than expected or cannot come back to the mooring? What if you get lost and come up somewhere you are not supposed to be and the boat is too far away to spot you? What if a problem arises underwater and you have to come up earlier than expected? What if you get separated from your buddy and have to ascend on your own?
These unplanned for issues, and more, can come up on any dive. And while they are not a huge problem in and of themselves, each of these scenarios has the potential to become a difficult situation if you are not seen or if ascend without a visible device. Being able to signal from underwater or when you get to the surface will hugely alleviate any stress or danger caused by the situations listed above. So buy a surface marker buoy, learn how to use it, and bring it on each and every dive.