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Why and how to use an SMB when diving?

Updated: Jul 7, 2019

Using an SMB is an essential skill to be a safe and independent diver.

It's use is now part of the PADI Open Water course but many divers in training often only get one quick shot at it.

Let’s have a closer look at different types of surface marker buoys and how to use a safety sausage comfortably.

What is an SMB?

Firstly, there is a certain amount of confusion between SMB and DSMB.

A Surface Marker Buoy (SMB) on paper is actually a smallish round/oval inflatable buoy that you drag along for the whole duration of your dive to signal to the boat your location. This can be useful when doing activities in shallow water, for instance scientific surveys, where boat traffic could be an issue. The instructor may also deploy it on first dives in shallow water to protect trainee divers who are still learning buoyancy skills, when boats are present on the surface.

Alternatively, a ’permanent’ SMB (same device as above) could be left at your point of entry to signal to boats that divers are in the vicinity.  This is especially useful in areas that are not marked by big boat buoys and are not established as regular dive sites.

The more commonly used Delayed Surface Marker Buoys (DSMB), that most of us have shortened to SMB or safety sausage, are the ones you would have tried on your Open Water course. They are an essential part of a diver’s equipment kit and every diver should have one. If you are boat diving, you really shouldn’t be in the water without one. They look like a big, long, often orange, inflatable sausage and may vary in size but usually are at least a meter long. They are often attached to a spool of string and the diver or the dive guide will launch it towards the end of the dive when the group is about to start their safety stop.

Diver with SMB in Nusa Penida Bali
Hanging out at the safety stop with DSMB

Why is the SMB such an essential piece of kit?

As you may have guessed by the name, the Surface Marker Buoy marks your position on the surface and this is very useful when a boat has to come pick you up. When there is swell and strong current having a 1.5meter bright orange tube to wave about in the air is much more effective than tiny hooded, dark wetsuit clad figures waving to attract the boat captain’s attention. So a DSMB will help you to be found by the boat and not get lost at sea: very useful, you might even say essential.

It is also quite handy when the current suddenly picks up or turns and you want to signal to the captain that this is happening. In this case you may launch the DSMB a little earlier so that the boat has seen your direction or speed change. Long deco stops may make divers drift so tech divers would use it in the same manner.

It also avoids waiting too long for the boat to get ready to come pick you up, the captain sees the SMB launched - in leisure diving that usually means the divers will be on the surface in 3 or so minutes - he can then start getting ready to come get you and be close by when you surface.

For safety stops it is also a useful visual reference to keep your depth and keep the group together. It makes it easier to hold the stop, you can take your eyes off your computer and it gives the group a ‘centre’.

In any instance a DSMB, (which can also be used as an SMB) is useful to signal to boats you are there. You might see it up when doing skills in a shallow pool like sandy area or whilst doing a safety stop in strong current with heavy swell, the conditions or situation are not the same but the finality of the DSMB use is: shouting: “I am here! I am here! Do not come too close to me with your propellers/ come pick me up!”

Popular amongst dive pros, the Apeks Lifeline spool range

How do you use an SMB ?

Techniques for launching an SMB vary widely and like in most things in diving it’s important to find what suits you. My technique is a hybrid between some tech stuff I learnt and a pretty common launch. When you send up your DSMB you don’t want it to drag you with it to the surface so the first thing you do is check that the spool is properly coiled and free of you, that no string is entangled in your gear and that you are in a good position to let it go quickly. In tech, this is even more important so one of the techniques I learnt when doing tech is to inflate the DSMB a little bit before launching so as to get it in a nice comfortable position. I do this by adding a little air from the escaped air from my regulator exhale, so I hold the opened end of the tube just above my inclined head and let a few bubbles go in. This make the DSMB stand vertically. I then organise myself so I have a finger through the spool (cleared so it can unravel) and the tip of the same finger and thumb holding the bottom of the sausage gently. I then use my alternate air source to blast in some air, enough for the sausage to be fully inflated on the surface (one good blast usually does it at 5m). This is what works for me. There are many other ways to do it out there so don’t hesitate to watch how others do it and then experiment till you find what is comfortable for you.

This is a skill you can practice during your PADI Drift Diver specialty for example, or that you will practice extensively during your PADI Divemaster internship. As a dive leader, it is essential to know how to use this safety equipment.

When diving in places with currents, check there is a safety sausage in the BCD pocket, if not buy one or borrow one but make sure you have one. After all it’s so much better when the boat picks you up straight away!

Turtle diving in Nusa Penida
Turltes don't use SMB when coming up...but divers should!


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