A Surface Marker Buoy (SMB) is absolutely essential kit for diving anywhere you may have surface boat traffic. A SMB 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.
Delayed SMBs, such as the AP Diving Buddy SMB, are designed to be deployed from depth near the end of, or at any critical point during, a dive. Some divers prefer to shoot their Delayed SMBs from the bottom. Other diver 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 SMB should you buy
There are essentially three choices for SMB 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.
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.
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.