What is a Surface Marker Buoy (SMB)?

If you have been diving a while, you would have noticed what looks like brightly-colored inflatable tubes that stick right out of the surface. In fact, on crowded dive sites, these weird-looking things can be seen poking out of the water everywhere!

Well, that floating tube is most likely a Surface Marker Buoy (SMB). SMBs play an important role in diving, both for recreational and professional or technical divers. In this blog post, we’ll take a closer look at SMBs and what they are used for. We will cover:

  • Types of Surface Marker Buoys
  • Do Scuba Divers Need a Surface Marker Buoy
  • Learning To Use a Surface Marker Buoy
  • How Do You Choose A Surface Marker Buoy
  • Care For Your SMB

So if you’re curious about SMBs, we have you covered! Read on!

πŸ›… 1. Types Of Surface Marker Buoys

There are several types of marker buoys that divers often see.

Surface marker buoy (SMB)

This type of buoy is designed to be deployed on the surface of the water to mark your location.

Delayed surface marker buoy

Commonly used in recreational diving and the topic of this article, this type of buoy is deployed at depth, often during or just before the safety stop. It denotes that a group of divers are right underwater and might surface soon.

It is also affectionately called a “safety sausage”. As you can imagine, inflating a giant tube orally and calling it a sausage is an open goal for many jokes!

Location marker buoy

This type of buoy is used to indicate a specific underwater location, such as a wreck or dive site.

Dive float

These are big inflatables usually with a “diver below” flag. Dive floats are typically inflated at the start of the dive and towed during the entire dive. It is used to mark a diver’s location while underwater, especially important in areas with heavy boat traffic.

They are often brightly colored and made of foam, which makes them easy to see from a distance. Dive floats can also be used to hold gear or supplies for a diver. Many freedivers tow them around while spearfishing to hold their catch or equipment as they descend again.

Dive float with "diver below" flag

❓ 2. Do I Need An Surface Marker Buoy for Scuba Diving?

Simply put, a delayed surface marker buoy is an extremely important piece of dive safety equipment that every diver should have. Some dive operations make it mandatory for a buddy team of divers to have at least one.

Makes You Visible To Boats

Firstly, an SMB protects you from dangerous boat traffic as you start your ascent and head towards your safety stop depth. It also warns boats that you are about to surface so that they can stay well away.

Secondly, it clues your own boat captain on your location, allowing him or her to easily follow your movements and get ready to pick your dive group up.

Increases Visibility

In addition, an SMB greatly increases your visibility, especially in locations with strong currents. You can easily drift away or get lost while doing your safety stop or while on the surface.

If you get separated from your group or buddy, an SMB can also make it easier to find each other or for passing boats to see you if you need any help.

It also makes searching for you way easier in the event that you get lost.

Marks Your Location During Drift Dives

SMB deployment during a drift dive also allows your dive boat to keep track of your whereabouts and follow your location as you’re getting whipped around by the current.

Signaling Tool

Lastly, you can use an SMB as a signaling tool or marker in an event of an emergency. A yellow SMB is the color most commonly used in an emergency.

Dive float used as signaling tool

🧭 3. Learning To Use Surface Marker Buoys

Like all things underwater, everything has a risk. PADI offers modules that cover SMB deployment so check with your favorite dive professional. In the interest of safety, we will not post step-by-step instructions on how to deploy an SMB as nothing can replace the instruction and monitoring of a qualified instructor that can teach the safest methods.

However, if you are already trained on SMB deployment, here are some tips that might help speed you along to becoming a sausage master. Hah! We told you. Loads of sausage jokes.

SMB Deployment Tips

  1. Never, EVER attach the sausage to you. It becomes an entanglement hazard and can result in disastrous consequences like getting dragged around.
  2. Try a finger spool if a reel is too bulky. A finger spool and SMB can fit easily into a BCD pocket.
  3. Bring a cutting tool just in case. It is better to be safe than sorry!
  4. Many choose to inflate their sausage with their primary regulator. You are supposed to deploy with the alternate air source and this is the method that PADI teaches.
  5. Keep the reel or spool away at an arm’s length when you deploy to avoid entanglement underwater
  6. Keep your depth and position steady when you inflate, as the sausage is buoyant and can float you up
  7. Good buoyancy control is key to deploying your SMB. You can let a small amount of air out of your buoyancy compensator device before deployment to compensate for the slight surge upwards.
  8. On your ascent, always reel in your SMB away from your body or equipment to avoid entanglement
  9. One of the first things we learnt scuba diving was that air expands on the way up. An SMB deployed at 10 meters will expand to twice the volume, so a fully inflated SMB might get damaged on its way up.

πŸ” 4. How Do I Choose An Surface Marker Buoy

There are plenty of options for your new SMB purchase with many different types.

Open Ended or Closed?

The first thing you should pick is whether you want a closed or open bottom. Closed SMBs have seals that ensure the air stays in.

Open bottom SMBs are simple tubes that have one opening at the bottom. Deploying is easier as they are extremely easy to inflate with air. In addition, at the end of the dive, they allow you to quickly deflate.

However, they can let in water and flop into a horizontal position. You can keep them upright by pulling them downwards, although water can still get in. Keeping the air in is easier in calmer waters when you can pull down on it.

Extra Features

Some SMBs have an over-expansion valve to prevent your sausage from getting damaged from the changes in air pressure on its way to the surface.

An SMB can also have an oral inflation valve that you can add air orally from. Just make sure you have sufficient gas!

Size and Color

An SMB can be up to 1 to 2 meters long. Which size you pick depends on where you will be diving. If you are regularly diving in large waves or choppy seas, you might want a bigger SMB to be more visible.

However, if you hang out in relatively calm waters, a smaller SMB might suffice.

The standard color of an SMB is red or orange. Even better if they have reflective tape or strips that can make you more visible at night or at sunset.

Diver holding a surface marker buoy

Storage During Dive

Check how your SMB will be stored during the dive. For example, there is usually a velcro closure or elastic loop to keep it in place during the dive.

Finally, it should also have a clip to keep it attached to your BCD during the dive and when not in use. Of course, you can also tuck it away in your BCD pocket if it is small enough. You won’t want to carry it around throughout the dive.

Reel or Spool?

Don’t forget, once you’ve chosen your SMB, you need to find a reel to attach to it. Many SMBs come with a basic nylon line that you loop around the rolled-up sausage but is often entangled and a mess to constantly deploy and keep.

In addition, the included line is usually only 5.5m long, the approximate depth of your safety stop.

Having a spool or reel will help in keeping things nice and neat.

β˜‘οΈ 5. Care For Your SMB

Like the rest of your dive equipment, your SMB needs a bit of TLC after your dive or at the end of the day. Saltwater can wreak havoc on equipment, and while an SMB is more forgiving than other gear, a quick rinse wouldn’t hurt.

You can inflate your SMB at the end of the day and quickly rinse the inside and out of the SMB with fresh water. Don’t forget to give your reels, spools, and lines a quick dunk in the freshwater tank as well.

πŸ’­ 6. Final Thoughts On Surface Marker Buoys

So there you have it – all you need to know about surface marker buoys.

If you’re ever out on the open water and see one of these babies, now you know what they are!

Experienced divers use them frequently in individual buddy teams instead of relying solely on your dive instructor or guide for their safety.

On your next trip to the dive store, be sure to add an SMB to your must-have list. Dive safely and happy bubbles!

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