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Surface Marker Buoys (SMBs)

Being able to let the surface know where you are during a dive is critical in some situations, and highly recommended in most others. The main ways divers use to achieve this are: a Surface Marker Buoy (SMB) which stays on the surface, with or without a dive flag; a Delayed Surface Marker Buoy (DSMB) which can be deployed by the diver from underwater; or a Safety Sausage which can only be deployed on the surface.

We consider the Safety Sausage to be unsafe and don't sell them. After all, how do you safely get to the surface in areas where there is boat traffic in order to deploy your safety sausage. They are usually much smaller than DSMBs, and thus don't do nearly as good a job as a signalling/location device.

Most people refer to a DSMB as just a SMB, which is why this category is called Surface Marker Buoys (SMBs), but technically they're very different.


A Surface Marker Buoy (SMB) is floated on the surface during a dive to mark the diver's position during drift dives, night dives, mist or disturbed sea conditions. A SMB is absolutely essential kit for diving anywhere you may have surface boat traffic. It allows your position to be known by people watching from shore and watercraft, whether they be the boat you are diving from, or other water users. Typically a SMB will have a dive flag on it as well. See Surface Markers for our range of SMBs.

A Delayed Surface Marker Buoy (DSMB), decompression buoy or deco buoy, is deployed whilst the diver is submerged and generally only towards the end of the dive. The DSMB marks the diver's position underwater so the boat safety cover can locate the diver even though the diver may have drifted some distance from the dive site while doing safety or decompression stops. A reel or finger spool and line connect the buoy on the surface to the diver beneath the surface.

Our recommendation is that all divers should carry a DSMB and reel on every dive. In many boat diving situations it's also good practice to also have a Surface Marker with dive flag up on the surface to tell your surface support where you are for the whole of the dive.

SMBs and DSMBs are not intended to be used to lift heavy weights. That's what a Lift Bag is for.

Where to Deploy Your DSMB

Delayed SMBs, such as the AP Diving Buddy DSMB, are designed to be deployed from depth near the end of, or at any critical point during, a dive. Some divers, like us, prefer to shoot their Delayed SMBs from the bottom and thus let the surface support know they're begining their ascent. Other divers shoot from mid-water when they start their safety stop, or decompression stops. We strongly recommend you have a Delayed SMB and reel/spool with you on every dive. On open water dives, waiting until you surface to deploy a surface only safety sausage is dangerous in high boat traffic areas.

Which Colour Delayed SMB Should you Use

There are essentially three choices for DSMB colouring — all Red, all Yellow, or Red and Yellow on contrasting sides.

Studies have shown that Red and Yellow are the two most visible colours at sea. But each colour works better than the other in different conditions. Thus if you look around a dive shop, you will see up to three SMB colours: all Red; all Yellow; and one side Red, one side Yellow.

Recreational Diving

An all Red SMB is far and away the most common SMB colour. This leads some new divers to buy an all Yellow SMB so theirs will stand out more when at a busy dive site. We don't recommend this.

Other divers buy the two-colour SMBs (Red on one side, Yellow on the other side) because these must surely be the ideal for high-visibility over the widest range of conditions. For recreational diving, especially when ocean diving, this is what we recommend. However, it is essential that you let your surface cover know that your combined Red and Yellow SMB is not being used as an emergency signal unless an emergency signal or message is attached to it.

Advanced/Technical Diving

In Australia, and many other parts of the world, there is a convention used by more advanced and technical divers that an all Yellow SMB is an emergency signal, to be responded to by sending down a cylinder of gas, or a rescue diver, or both.

Whilst for the most part recreational divers do not have or need such a signal, it is possible for both types of diver to be on the same dive site. If one group of divers is using Yellow as an emergency signal and the other group uses Yellow as standard, this could lead to confusion and even to a genuine emergency signal being ignored.

For this reason, unless you have a very strong reason for wanting an all Yellow SMB as standard, please don't buy one.

If you decide that you would like to use a Yellow SMB as an emergency signal yourself, two precautions to take are:

  • Make sure your surface cover knows this convention
  • Mark the SMB with "EMERGENCY", "HELP", "SOS" or some other such message in large, clear black letters to ensure there is no doubt that you are a diver in distress and not just a diver who thought a Yellow SMB looked nicer than a Red one.

How to Deploy a SMB

How to Deploy a SMB

One of the best emergency signaling devices that can be carried by divers, and we recommend that every diver carry on any open water dive, is the inflatable signaling tube also known as a Surface Marker Buoy (SMB), or Delayed SMB.

With the increasing number of high-profile reports of lost divers and serious surface accidents involving boats, the importance of brushing up our scuba safety skills has only been heightened. For those who have never deployed an SMB before, but have watched a fellow diver or instructor shoot one up, you may think there's not much to it. However, this couldn't be further from the truth.

The most common problems inexperienced divers face with deploying a SMB are tangled reels, divers attaching themselves to reels, or divers not being able to control their buoyancy during deployment. All of these problems can lead to pretty serious ascent rate issues and ultimately increased risk of decompression sickness.

Though often referred to as the same, SMBs and Safety Sausages do differ. Safety Sausages are deployed at the surface for signaling. A Surface Marker Buoy (SMB) is deployed from depth, and often features an over-pressure relief valve (OPV) as they are closed tubes.

Surface maker buoys or SMBs, are big, inflatable tubes that mark a diver's location. They are brightly colored and sometimes feature reflective materials for additional visibility. SMBs are very useful and could potentially save your life — but only if you know how to use them.

Surface marker buoys (SMB) are effective when deployed underwater as intended. This gives the boat or divers at the surface a heads-up that you are making your ascent. That's why we think deploying it on the surface, or using a Safety Sausage that can only be deployed on the surface, is stupid. After all, how did you safely get to the surface if there is boat traffic in the area?

While the features of the Surface Marker Buoy may differ according to the type you're using, here's a general step-by-step guide to deploying a SMB from a depth.

Start Early

SMBs can be inflated at the surface but are truly effective when deployed underwater. This gives the boat a heads-up and allows it track divers prior to them surfacing. In many instances this gives the boat time to get into position to pick up divers as soon as they hit the surface, something that is especially useful if currents are strong, or if emergency assistance is needed. It also enables you to warn other boats that you're there and that they should keep clear. Many technical divers deploy their SMB at their first deco stop. Most recreational divers deploy it from their safety stop. We recommend you deploy your SMB before you start your ascent. This means you're doing it from a deeper point which makes it easier to control your buoyancy, plus you don't have to get as much air into the SMB. It also tells the dive boat you're starting your ascent.

Check Your Surroundings

Before you begin, ensure you are neutrally buoyant. Make sure your buddy and any other divers are far enough away from you to avoid the possibility of them becoming entangled up in it. Also check to see above you that the SMB will not come into contact with another obstruction, diver, boat, or take out a group of open water students above you!

Signal Your Dive Buddy

Let your dive buddy know what you're about to do. Signal them, 'You, Watch, Me, Shoot' and wait for them to repond with 'Okay'. That's also the signal to tell them to maintain their depth, so that you can work off them, instead of you having to monitor your own depth.

Prepare Your SMB

Take out your SMB from where you stored it. Many people like to store their SMB and reel in a BC pocket. We prefer to have the reel clipped to a D-ring on the BCD, while attached to the BCD which is held on the side of the BCD in a bungee cord loop. It's ready to go. However, if the reel line isn't already attached to the SMB, you'll have to attach it. Generally, most SMBs have a small D-loop located on the bottom of them. You need to attach the SMB lower D-loop to to a loop in the line from the reel. Once through, unreel just a little line, to make sure the loop in the line isn't tangled round the reel. Look up and check that there are no obstructions and ensure you aren't entangled in or attached to the SMB or line.

Get Ready To Deploy The SMB

Once cleared to deploy, wrap up the reel, line and any excess SMB material into one hand. Making sure that no materials like the line are wrapped around your fingers or dive gear and the reel is unlocked. Holding the SMB and reel with the left hand, inflate the SMB.

Fill Up The SMB

How you do this depends on the SMB — but no matter what method you use, it's important to practice! Many SMBs have openings at the bottom where you can vent air from your regulator to fill them up. You can do this either by purging your occy underneath the SMB or holding the opening above your head to catch your exhaust bubbles — there is no need to take your primary out of your mouth! SMBs with oral/low-pressure inflators can be filled using your BC inflator hose, just remember to replace it back on your BC when you are finished! If you use an SMB often, you can also attach a secondary inflator hose to your regulator's first stage so you don't need to undo your BC inflator hose every time. If you need to inflate the SMB orally, remember to save enough breath to clear your reg between breaths and to never hold your breath. At depth, a small puff of air will suffice to hold your SMB up at the surface, because the gas will expand as it ascends. This is why we prefer to shoot from the bottom of the dive.

Let The SMB Go

Keep a solid grip on the reel, but don't hold onto the line or SMB after it begins to ascend or you may be pulled up with it in a rapid ascent. If you have trouble staying down, try making yourself slightly negatively buoyant, or try adding less air to your SMB. If the reel gets caught and starts to pull you to the surface, let go of it. Never attach yourself to the reel. Once it reaches the surface make sure to hold the line taut so the SMB stands straight up in the water.

Make Your Ascent

When the SMB hits the surface, wind back the line on the reel and apply some extra tension on the line in order to make the SMB stand straight up. Make your way to the surface while reeling in the line so it stays taut. Slack in the line can cause the SMB to fall to the side and allow air to escape. Ascend at a safe rate and don't forget to do your safety stop.

At The Surface

When you reach the surface continue to pull down on the SMB so it remains upright until the boat is ready to pick you up.

An Example Deployment

This video shows an example SMB deployment. Note the 'You, Watch, Me, Shoot' hand signals at the beginning. The diver is using a finger spool instead of a reel, and inflating the SMB orally, which are both harder to get right.

SMB Colours

SMBs can be used to signal the need for a boat pick up, as a distress signal, a marker of a location, or to indicate the need for additional air on long decompression stops. Red or Orange is the standard colour for a SMB. A Yellow SMB is supposed to be an emergency signal. Red/Orange can be better seen in some weather conditions, and Yellow in others. That's why we like using a SMB that's Red/Orange on one side and Yellow on the other.

Practice Makes Perfect

Practice deploying your SMB in a controlled environment, or pool, if possible the first time around and then on all your dives to get proficient with the skill. 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 for help.

Best SMB and Reel Choices

  • Top Dive Reel
    AP Diving Ratcheted Pocket Reel with 45m (147ft) Line AP Diving Ratcheted Pocket Reel with 45m (147ft) Line
    RRP: $179, Our Price: $162, You Save $17 (9%).
    Many recreational divers have no signalling system, or at the very least just a safety sausage. They shy away from having a proper reel and SMB because they find them intimidating or bulky. Well the Buddy Pocket Reel is the perfect solution to the problem of bulky and cumbersome SMB/Navigation reels. It can be easily stowed in your BCD pocket or clipped unobtrusively to a D-ring.
  • Top Dive SMB
    AP Diving Buddy Self-Sealing Delayed SMB AP Diving Buddy Self-Sealing Delayed SMB
    RRP: $99, Our Price: $90, You Save $9 (9%).
    This is our favourite surface marker buoy. It features closed-circuit (one-way valve) construction, which prevents air spill at the surface. Inflate on the surface to attract visual attention, or use as redundant flotation. Inflate at depth to send up as a surface marker. You can chose between all red, all yellow, or combined red and yellow coloured Buddy Self-Sealing SMBs.

With this self-inflating SMB you can make deploying your SMB really easy!

  • Top Self-Deploying SMB
    AP Diving Buddy Delayed SMB with Mini-Cylinder Inflation - SMBCi AP Diving Buddy Delayed SMB with Mini-Cylinder Inflation - SMBCi
    RRP: $519, Our Price: $395, You Save $124 (24%).
    A real gem of a product, the Buddy SMBCi features an independent inflation mini-cylinder available with either DIN or Int A-clamp fittings. Deployment is simply a question of unfurling the SMB and cracking open the mini-cylinder. You'll have a full stiffy on the surface every time.

For teaching DSMB deployment AP Diving has manufactured a specially designed small DSMB.

  • AP Diving Training Delayed SMB AP Diving Training Delayed SMB
    RRP: $125, Our Price: $112, You Save $13 (10%).
    A must have for all dive instructors this DSMB allow trainee divers to practice deployment multiple times without serious depletion of gas supplies. The instructor can pull it back down and prepare it for the student to use again.

For more reel options, please see Dive / Wreck / Cave Reels, alternatively see Dive Finger/Jump Spools.

For more SMB options, please see Surface Marker Buoys (SMBs).

Deploying your SMB is an important skill not to be overlooked or ignored. Once you're proficient, you'll deploy your SMB often. Dive Safe!


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