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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.

Boat Diver Safety Briefings

Boat Diver Briefings
Lloyd Borrett briefing Peter Fear aboard "Raydon"

Many boat owners may welcome guest divers onboard their boats and prudent ones will give everyone a proper boat safety briefing before heading out. But what does a good briefing include and what might guest divers need to know about your boat if anything happened to you?

It's essential that you use a prepared guide to properly brief everyone onboard before heading out. You need to consider how they will respond in the event of you falling overboard or having a medical emergency? Don't assume people will just know. So have a plan, keep it simple and be consistent.

Here is a checklist of the key things to make your guests aware of:

  1. Boat Layout and Moving Around
    Boat layout and location of kit. Moving around the boat safely — one hand for yourself, one for the boat because the boat can move unpredictably.
  2. The Journey
    Where you're going and your route plan. How long you expect it to take, the weather and sea state expected, and things to look out for along the way. Also mention sun exposure and keeping warm.
  3. Lifejackets
    Where the lifejackets are and how to put one on. When to wear them. Ideally the lifejacket will be an automatic inflation, so explain how that works.
  4. Emergency Procedures
    Mayday procedure, with a note of it next to the VHF radio. Man overboard reporting (shout to raise the alarm and point to hold their position). Also explain what to do should they fall in.
  5. Boat Controls
    Basic boat and engine controls. How to shut off the fuel. How to start, stop and turn — and to do this the moment someone goes overboard.

We recommend using a Boat Safety and Dive Equipment sheet to conduct the briefing. An example is available for download below. Create your own and have a laminated copy kept together with other safety information on the boat for reference in an emergency.
Download/view the Raydon Boat Safety and Dive Equipment (Adobe PDF | 281.3 KB) sheet.

Listen to the Safety Briefing

As a diver on any dive boat it's essential that you listen to the Safety Briefing. It's there for a reason. Even on an airline, passengers are asked to pay attention no matter how frequent a flyer they are, because although the brief appears consistent, there are subtle differences between each aircraft.

Now compare that fact with the different dive boats you have been on. Things can happen remarkably quickly at sea and being able to remember where the lifejackets are, or even just the O2 kit for a DCI incident, will help you respond quickly and in a controlled manner.

Having listened to the Safety Briefing, it can be helpful to run through in your mind some simple 'what if' scenarios so that you better imbed the Safety Briefing in your mind.

Participation Agreement, Consumer Waiver and Concent Forms for Dive Boat Owners

We suggest that everytime you have divers coming out to participate in scuba diving activities from your boat you also ask them to read, understand and consent to the terms of a Boat Participation Agreement and Consumer Waiver. An example is available for download below. It should also be clearly displayed in the boat.
Download/view the Raydon Boat Participation Agreement and Consumer Waiver (Adobe PDF | 15.68 KB) sheet.

You should ask all divers to read and sign that they accept and/or will comply with the requirements for Scuba Diving From Your Boat. An example form is available for download below and it should be provided for each diver to sign before heading out on the boat.
Download/view the Raydon Boat Diving Consent Form (Adobe PDF | 155.5 KB) sheet.

Other References

The Dive Boat Related files on our Diving and Snorkelling Downloads web page are valuable references that will help you to better setup your boat for diving, and help you to conduct safe diving operations.

See also, Boat Diving Safety.


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