Surface Signaling Devices
Divers have at their disposal a broad spectrum of tools for signaling at the surface. In some cases, when a diver is not too far from the dive boat, a simple arm wave or waving a fin in the air can be sufficient to draw the attention of the boat crew. But when a signal must be sent over a greater distance, better tools are needed. Some of the more common tools carried by divers include marker buoys (safety sausages), air- and lung-powered horns such as a whistle or Dive Alert and signal mirrors. The effectiveness of signaling equipment is often dictated by the type of diving in which divers are engaged, and the local environment where the equipment might be used. A thorough training program will impart to students a basic knowledge about the selection and use of these important safety tools.
Safety Sausages and Marker Buoys
One of the most common items of signaling equipment carried by divers is the safety sausage, or surface marker buoy (SMB). An essential element for those who engage in drift diving, these inflatable devices enhance by a wide margin the crew's ability to spot a diver in the water.
In many environments, divers prefer to use what is called a delayed SMB. These are simply SMBs that are deployed at the end of a drift dive to provide a visual signal for the dive boat, and to provide an easier means of making our safety stop at the end of a dive while waiting for pickup. One important consideration we must be aware of as instructors is that divers sometimes have problems deploying delayed SMBs. Divers who have not been properly trained in the use of these devices will make procedural mistakes that can result in injury. For example, untrained divers often clip themselves to the devices when inflating them, and then a jammed reel can drag them quickly to the surface.
When choosing a safety sausage or SMB, one of the cardinal rules is "the bigger the better." Experts recommend devices that are taller, and at least 4-6 inches in diameter. Ideally, choose equipment that is of high quality, and look for features that can enhance its functionality, such as reflective elements, strobes and attached signal mirrors.
Horns and Whistles
Most divers carry with them a whistle that can be used as a signaling device to attract attention. In relatively calm conditions, and when the dive boat's engine isn't running, these devices do a great job to signal the boat crew. We should explain to our students that these devices are simple, reliable and economical, but that they are just one available tool and should not be relied upon in all situations.
Another excellent audible signal about which we can inform our students is the air-powered horn. These devices attach to the auto-inflator hose, and the greatly enhanced sound levels developed when using a compressed air source can travel much greater distances. However when your air cylinders run out of air, their air horn stops working.
Another very economical and easy-to-carry item of signaling equipment is the signal mirror. These can be used to provide a visual signal to boat crews or passing aircraft, and in ideal, sunny conditions have been known to be effective for great distances. While these devices are easily carried, we should point out to our students the limitations: They only work in sunny, daylight conditions, and they require a certain degree of user knowledge and skill. While a signal mirror isn't too difficult to use, the place to learn isn't when you're floating alone in the middle of the ocean.
Strobes and Lights
When it comes to night diving, or a situation in which picking up divers extends into the hours of darkness, strobes and dive lights offer another excellent means of sending out a signal. Many divers carry dive lights with them even on daytime dives, so these are a common tool that divers are likely to have available. Once the sun sets and darkness settles in, even a small light can be seen for a great distance, making it much easier for stranded divers to be located and recovered. Shining a dive light on the side of a safety sausage can greatly enhance its visibility, and adding a strobe to the top of the device can likewise make it more visible.
Sea and Sky Markers
Among the less commonly carried items of signaling equipment are pyrotechnic devices (signal flares) and sea marker dye. Marker dye increases the visibility of a diver from the air by coloring a relatively large area of the sea surface. While these may not help a dive boat spot a diver, they can be helpful when awaiting rescue from the air.
Flares are highly effective in drawing attention to would-be rescuers both in daylight and nighttime conditions, and those that can be carried underwater for use on the surface are also available. Not only can such devices be used to signal a dive boat or air rescue elements, they can also be used on board a dive boat to help guide rescuers to their location for evacuation of an injured diver.
When it comes to surface signaling devices, maintenance can sometimes be an important consideration, and that's a point we should make loud and clear with our students. If neglected, items like safety sausages and the line reels we use with them may not function properly when needed. To ensure their readiness, these items should be regularly cleaned and inspected to ensure proper operation when needed. The line reels should be properly lubricated as well. Dive lights should always be equipped with fresh batteries or a full charge -- just in case.
Pyrotechnic devices have expiration dates, and should not be relied upon for use after expiration. Like much of our regular dive gear, these items should be checked on a regular schedule and replaced when needed.
Practice Makes Perfect
Emergency skills are something that should be practiced on a regular basis so that they are ready when needed. Before a trip in which such equipment is recommended (or required), take the time to check your gear and practice the skills needed to use it effectively.