Here are a few items you can include in your logbook to help you stay organized and honest, track progress, and work on self-improvement as a diver.
As soon as you get into the water and see the unbelievable night life, you will understand why so many divers love it.
The following are sensible suggestions of things divers should never do, based entirely on common sense.
This article focuses on one specific aspect of deploying an SMB: methods for inflating the SMB.
by Dr. Thomas Powell:
Modern dive teams operate within a world inundated with technological advances. In years past, teams relied on experience, skill, and hard work. Teams today still maintain those attributes, but they also have capabilities and support structures that far exceed dive teams of the past. Technology can eliminate some of the busy work, frustration, and extensive hands-on searching that divers were once required to perform.
One of the first technologies to help dive teams around the United States was sonar. Side-scan and down-scan sonars allow dive teams to view bottom topography and look for abnormalities despite black water, currents, or short-staffed teams. Essentially, a boat operator can work with a sonar operator to cover large areas quickly when a team is searching for an object with known dimensions. As a comparison, dive teams of the past may have looked all day in a brown-water lake for a stolen vehicle that was submerged; whereas today, with the right technological assistance, a dive team can cover the same search area in a fraction of the time. This technology also provides increased safety because divers may only enter the water when a target or potential search item is located. This scenario suggests that fewer divers would be needed and the potential dive time for the associated team could be reduced. When fewer people are in hazardous water for a shorter period, the likelihood for problematic instances is reduced. The hazard reduction is further amplified when a team takes into consideration the fact that active divers will be fresh and ready to enter the water as needed.
A second technology that is still fairly new for dive teams is dive computers. Dive computers allow dive team members to record critical data such as depth, dive time, and temperature. These data sets are things that recreational divers may take for granted, but could help provide critical information to a criminal investigator or medical examiner. Though dive computers have been around for many years, technological innovation has allowed basic computer systems to record more information and support the use of various gas mixtures for divers. In a world where dive team missions grow more complicated and public safety work environments may remain unknown or unsafe, the more information available to dive teams the better. Similarly, backup digital recorders have been developed and are available to teams as redundant data recording devices. In court rooms, the concern is that a standard dive computer may have been manipulated or altered. These simple data recorders are clipped onto a diver during an operational dive and can be handed off to investigators to ensure redundant data sets and unaltered evidence sources for courtroom proceedings. The use of both dive computers and redundant data recorders can also allow a dive team to record information about a dive site to be better prepared for potential future operations in the same location.
Third, dive teams everywhere have started to use subsurface electronic communications systems. These systems may be hardwired or wireless, but in both cases the objective is to allow a diver to actually speak to surface personnel. Many of these systems even allow for digital recording capabilities. Essentially, a diver can speak in detail about what he or she finds, and how to proceed with a dive. Team leaders and tenders can also provide complex direction to a diver if issues arise or mission changes develop. Rather than relying solely on line-pull techniques, many dive teams use electronic systems for primary communication and train to use line-pulls as a redundant back-up source. The concern is that teams must still train to use line-pull communication methods and then practice these methods. Reliance on electronic systems can lead to failure if the “tried and true” older methods are not maintained.
Fourth, teams can make use of location recording devices. Global positioning systems (GPS) allow dive teams and investigators to record dive site locations, entry locations, and in some cases even evidence recovery locations. Systems such as handheld GPS units or boat-mounted GPS units can allow a location recording to be taken directly over an evidentiary collection point. Similarly, systems such as rangefinders allow shore personnel to take distance measurements from known entry locations to collection points or marker buoys. Simple rangefinder applications are even available for modern smart phones. Other smart phone applications can allow tenders or team members to take digital compass headings that can be imprinted over digital pictures to show important location information and how it visually associates with an operational dive area. These systems all allow a dive team to better record its actions and how operations were performed in relation to a dive site. Information such as this can allow a scene to be recreated and show credible proof that items were recovered from areas claimed by dive team members.
Next, modern dive teams often make use of metal detecting systems. These systems may be mounted on watercraft or carried by individual divers. Metal detectors allow a dive team to find and recover items made of various types of metals submerged underwater. A single diver may use a hand-held metal detector to find a small piece of evidence such as a handgun, or a boat mounted detection system may be able to locate larger items such as a submerged vehicle or watercraft. Again, items of this type can reduce search times and allow for more rapid and less problematic recoveries.
Finally, imaging and lighting systems are critical for dive teams. Pictures and video allow dive teams to show where items were found, the environment around these items, and the manner in which these items were recovered. With advances in small digital imaging devices, dive teams can now mount cameras to full-face mask units or other gear components. An entire dive operation can be filmed using a “hands-free” technique. Imaging evidence of this type can prove in a court room that a dive team followed proper procedure, and that items were recovered in locations claimed by dive team members. Similarly, in waters where visibility is a factor, lighting systems may expand visibility or allow for improved imaging. Everything from basic hand-held lights to large canister-powered lights can also be mounted to full-face masks systems or strapped to the back of a diver’s hand. Again, lights can be operated in a safe fashion that allows the user a full range of dexterity with both hands. Where imaging was once not a factor during subsurface operations, the entire duration of a public safety dive mission can now be recorded and if helpful, illuminated.
Technology has advanced the capabilities and resources available to operational dive teams. With each passing year, new innovations make dive operations safer and more efficient. If dive teams choose to make use of innovative technologies, teams must train to use these items to ensure safety and operational success. It will be exciting to see what comes next and how safe rescue and recovery operations may become in the future.
– Dr. Thomas Powell
Owner/Instructor Trainer – Air Hogs Scuba, Garner, NC
by Lauren Kieren:
Picture a clear sky, slight breeze, warm sun beating down on flat calm seas, and limitless visibility underwater… What could make this picture perfect dive day go from fantastic to terrible? Having to skip out on a dive! If you are a new diver or this is your first dive of the season – there are a few Do’s and Don’ts to consider before taking a giant stride in and having to skip out on a dive. This list by no means covers every item to consider, but it’s a good head start to diving back in.
To start, don’t compare scuba diving to riding a bicycle. We all know the saying, “if you don’t use it – you lose it,” the saying applies to diving as well. Regardless of how many certification cards are in your wallet or how many dives you have logged, after a period of inactivity, your skills will diminish over time.
Do participate in a SDI Inactive Diver or refresher course if you have not been diving within the past 12 months. It’s better to go through a tune up in a pool or confined open water setting under the guidance of an active dive professional versus trying to figure everything out during your initial descent.
Don’t forget your certification card while prepping for your dive trip. Nothing is worse than having your gear packed while you’re getting excited for the dive, and you get turned away during check in for not bringing your certification card. If this happens and the location has internet access, you can verify your SDI Certification online without missing the dive and order a replacement card.
Do check in early for your dive trip. You might be able to pick the best spot on the boat or find an empty bench if you’re shore diving. Allow yourself some time to set up your gear without rushing and verify all of your equipment is on, functioning, and ready to dive.
Don’t be “that guy” (or gal) on the dive boat or at the shore site with a suit case full of scuba equipment exploding all over the place. This can cause people to trip over it and it can be invasive to their personal space to set up.
Do make a checklist of necessary dive equipment for the day, lay everything out before packing it, and only bring what you need. If you are diving off a boat, store your empty gear bag under the bench and be attentive to keeping your equipment streamlined and confined to your space.
Don’t get yourself in trouble or put yourself at unnecessary risk of Decompression Sickness (DCS) by not paying attention to your personal dive computer (PDC). Don’t be “that guy” (or gal) who ends up back on the dive boat or shore location with a screaming dive computer sounding like a fire truck coming down the road.
Do keep an eye on your PDC and pressure gauge during the dive. In addition to your depth, time, no decompression limits, and air consumption rate. Get to know the functions of your computer and learn how to read the displays before making the dive. Take the proactive approach to safety in the water and be aware of your limitations. Your first dive of the season or after a period of inactivity can go by very quick! Pay close attention as the time may sneak up on you.
Don’t ascend faster than your bubbles.
Do CYA… Computerize Your Ascent. Your dive computer is a necessary piece of equipment; no different than your mask and fins. It’s a fantastic tool to utilize to enhance the safety of your dives. During your ascent, pay close attention to your computer. Most modern day computers have an ascent alarm to warn you if you’re going up too fast. If your computer does not have an ascent alarm, watch your depth and time to ascend no faster than 18M / 60FT per minute.
Finally, don’t forget to have fun! Do give us a call or send an e-mail to tell us about your dives. While we’re stuck in the office, we want to hear about your fun, exciting experience underwater!
Did you like these condensed Do’s and Don’ts for your first dive back in? Feel free to pass these on to your dive buddies and share it on Social Media. If there are specific Do’s and Don’ts you want to see, let us know in the comment section below. We will continue to add more Do’s and Don’ts lists in the future so keep an eye out for the next round to come!
by Jon Kieren:
#AreYouSureThatisaGoodIdea | #SupportYourLocalDiveCenter
As divers, it’s hard to imagine a better summer day than hanging out on your buddy’s boat, doing a little diving, maybe a little fishing, and just relaxing enjoying the sunshine. When all goes well, it’s the perfect way to spend a day out of the office, but what about when it hits the fan? Do you and your buddies have the equipment and skills required to handle the worst case scenarios? While a day out on your buddy’s boat can be a lot of fun, if you are not properly trained and equipped it is probably a better idea to spend a few bucks and head out with your local dive charter instead. Professional dive charters offer more than just a boat ride; they have trained staff and the necessary equipment to handle emergency situations, and could very well save your life. A few points to consider when deciding whether to head out on your buddy’s boat or dive with a professional dive charter are:
- Equipment-If you’ve ever been on a dive boat, you’ve probably heard a safety briefing given by the captain or crew. This briefing typically outlines emergency procedures and describes/shows where to find emergency equipment onboard. This briefing is not just for show, this emergency equipment can save your life, and typically includes:
- PFDs (life jackets)
- VHF Radio-for hailing coast guard, EMS, other vessels, etc.
- Fire suppressant devices
- EPIRB- Emergency Position Indicating Radio Beacon
- First Aid kit
- Emergency Oxygen
Not only do dive charters stock this equipment onboard the vessel, the crew is trained in its use. Do you and your buddies have access to this equipment? Are you confident in your ability to use it in a high stress emergency?
- Crew- Are you and your buddies experienced and qualified mariners and rescue divers? In the event of an emergency in/on the water, you need to have well trained personnel on hand to lend assistance effectively. Are you and your buddies trained and prepared to handle the following situations?
- Distressed/Unconscious diver in the water
- Fire on-board the vessel?
- Weather suddenly turning while divers are in the water
- Lost/missing divers
- Decompression sickness and other diving injuries
Dive charters staff professionally trained and experienced crew members to assist and handle these types of scenarios. These crew members are often overlooked, because most of the time their skills are not required. But when there’s a problem, you will be glad they are there to help.
Unless you and your buddies are very experienced mariners and divers, we strongly recommend choosing to dive with a professional dive charter instead of heading out on the water alone. Dive emergencies happen quickly and unexpectedly, and having trained professionals and the proper equipment on site can turn a potential fatality into a minor hiccup in the day’s events. Next time you’re thinking about going diving, let the pros do all the work and head out with your local dive charter. To find an SDI facility in your area, click here.
by Lauren Kieren:
Drift diving is like flying underwater. When you are soaring along the bottom contour, neutrally buoyant, guided by a gentle current, watching the marine life; it gives you a perspective of the underwater world that is difficult to obtain any other way.
Depending on where you dive, Divemasters (DM’s) and dive operations may use different techniques for drift diving. In many cases, drift dives are conducted off a boat while a DM guides the direction of the dive while towing a Surface Marker Buoy (SMB) to mark the divers’ location in the water. Meanwhile, a boat might be following the group to pick up divers as they surface (keep in mind, drift diving from a boat requires a skilled boat operator to conduct drift diving procedures properly).
Prior to participating in drift diving activities, you should be extremely proficient in your diving skills. If you have not participated in diving activities for a period of six months or longer, we highly encourage a diver to go through the SDI Inactive Diver Course before considering this type of advanced dive. Setting up a drift dive can be a fast paced activity that requires your diving skills and techniques to be dialed in – the ascents and descents can be challenging but once you are on the bottom… It’s your time to cruise along the ocean floor.
So what should you consider before drift diving? Here are a few tips and tricks before you hit the water:
STAY AHEAD OF THE GAME – Prior to entering the water, ensure all of your dive equipment is on, functioning, and you have completed a pre-dive safety check. Make sure you are properly weighted so you can descend with the group. If you are having difficulties equalizing on the descent – signal to your buddy and be aware of the divers’ location on the bottom, and the surface marker buoy signaling your location. If conditions allow (good visibility and manageable current) slow your descent to catch up with the group. If conditions do not allow for this and you cannot catch up with the group, surface with your buddy to abort the dive.
GO WITH THE FLOW – Once you are on the bottom, it’s important to “go with the flow.” Avoid swimming against the current, as this will increase your work load and air consumption rate. Streamline yourself and your gear to glide effortlessly through the water. Keep an eye out in front of you to plan your moves accordingly. If you see obstructions ahead of you – whether it’s a coral head, a wreck, or a cluster of fishing line – it’s important to plan your moves ahead of time to avoid a collision.
SELF AWARENESS – As previously mentioned, the descents of a drift dive can be fast paced. It is extremely important during all dives (especially drift dives), to monitor your depth gauge to ensure you are staying at a consistent depth versus drifting downward or upward without realizing it. Also, keep a close eye on your no decompression limit (NDL), as you glide along the bottom your air consumption rate may be reduced due to the lack of physical exertion required during this phase of the dive. Remember, just because you have ample an amount of cylinder pressure remaining, does not mean your NDL, or bottom time hasn’t exceeded the limits. Finally, check your tank pressure early and often and make sure you will have an ample supply of breathing gas to make a slow ascent, conduct a safety stop, and safely surface with some remaining tank reserve.
MAKE YOURSELF NOTICEABLE! – No, we’re not talking about wearing flashy dive gear… Prior to ascending, make sure to keep your eyes open and your ears tuned for boat traffic. If you and your buddy are surfacing before the group, ascend in sight of the SMB the DM is towing. Once at the surface, deploy your own Surface Marker Buoy, give yourself some distance from the SMB marking the divers underwater, then signal to the dive boat for pick up. If necessary, carry a whistle or audible alarm to be heard from a distance if you are not seen. When the boat makes its way towards you, stay put and do not swim towards the boat unless instructed by the boat operator.
Drift diving is a fun and exciting way to explore the underwater world, however, it can also lead to increased stress and anxiety if you are not prepared. This text is not intended to replace proper dive training, nor does it cover all aspects and requirements of drift diving. Following these tips along with proper training will ensure you get the most out of your drift diving experience.
I was alone. And it was all because I had stopped to take a few close-ups of a Moray. When I had looked up, my diving buddy and the rest of the diving group was long gone. We were all drifting in the same current, so I figured that the boat would be nearby when I decided to surface. Twenty feet above me, the last red rays of dusk faded, and inky darkness enveloped all but the faint glow of my dive flashlight. Below, a labyrinth of jagged coral canyons raced by as the current swept me along steadily.
The dive computer on my wrist beeped, signaling that my decompression stop was over. I reached down to turn it off, but I must have pressed the wrong button, because it kept beeping. I held it closer to my mask for a better look. And that’s when I hit the wall. Something in my shoulder popped, and then I bounced off the sharp coral several times until I lost my mask and regulator. I tried to reach back to catch my regulator, but my right arm wouldn’t move. I panicked, and all I could think about was getting to the surface, but I couldn’t see, and I couldn’t tell which way was up. I at least had the presence of mind to slowly hum to myself so that my lungs wouldn’t explode when I ascended, but doing so meant that I sank even deeper into the reef. I knew I was going to die.
In my blind terror, I searched around with my left hand for the button to fill my BC. I finally found it and filled the vest with as much air as it could hold, but it was already almost full, and I was still sinking. Even though my eyes were shut, I was starting to see stars. I knew I didn’t have long. “The weight belt,” I thought to myself… I fumbled with the release lever on my weight belt and let it drop away. I felt my descent halt, and then I started to slowly rise as my lungs screamed for air. I had no idea how far down I was, but I had run out of air. Once I knew which way was up, I started kicking frantically. I clawed my way to the roiling surface just as I was on the verge of losing consciousness, and then I almost sucked a mouthful of water as a wave hit me in the face. After a full minute of catching my breath, I started trying to get my bearings. It was dark and choppy, and the dive boat was nowhere in sight. The rest of the group would have surfaced in the last five minutes, so the boat had to be close. As I reached the top of a swell, I tried to kick higher so that I could see further, but the weight of my scuba tank made doing so difficult. We were miles offshore, and I couldn’t see lights in any direction. I had been drift diving dozens of times, but I had never been separated from my group. It started to dawn on me that the guys in the dive boat might actually not be able to find me. They would be looking for me now, and I needed some way to get their attention in the dark. I reached for my dive flashlight, only to find that I didn’t have it anymore.
My stomach sank as I realized that I had quite possibly doomed myself over a few stupid pictures. Pictures! This was my last chance. I reached back with my good arm, and sure enough, my camera was still secured to my BC and bumping against my scuba tank. I turned the camera on and held it as high over my head as I could. When I reached the top of a swell, I took a picture and let the flash go off. I did it again and again for five minutes, pausing after every flash to listen for sounds of rescue. And then the battery went dead. I stared at the camera in disbelief. It had been my only hope. Now, I was floating in the middle of nowhere, bleeding, dehydrated and alone. Every bad shark movie I’d ever seen came to mind, and I screamed in frustration. I kept screaming until my throat went raw.
I floated there, fully appreciating my situation, when I heard a voice in the wind. I thought it was my imagination at first, but I heard it again. As I reached the top of a swell, I scanned what I could see of the horizon. The dive boat was idling just 50 feet away, and it still had its flag flying to signal to other boats that there were scuba divers in the water. I flailed my arm wildly and shouted to get their attention until someone shined a flashlight in my eyes. The engine roared as they started toward me, but I kept my arm up so that they wouldn’t lose sight of me. I almost couldn’t believe it when the boat pulled up and reassuring hands caught hold of me. That was the last time I was ever going to get separated from my group on a drift diving trip.
Underwater navigation is a skill that you will use on every dive, and not just an end to itself. To be a good diver, you must be successful at underwater navigation. Good navigation skills will take you where you want to go, to do the things you want to do. Similarly, night diving and limited visibility diving skills will help you achieve the things you want to do underwater.
To navigate underwater, or make night or limited visibility dives, you will need some additional pieces of gear beyond what you may already own. These items include a compass, an underwater light, a slate, a marker buoy, and other devices. You will find that you will use these items throughout your diving experience.
Below is a list of the most common equipment used during a night dive and its purpose.
The Mechanical Underwater Compass
You can purchase an underwater compass with a variety of mounting options. They can be mounted on your console with your other instruments. Wrist models are preferred by some divers, while others choose to wear theirs attached to their buoyancy compensator, using a spring loaded retractor.
Underwater compasses are usually made from rugged plastic. They will withstand a great deal of abuse, but should be treated with respect and care. A simple rinse with fresh water at the end of your diving day is usually all the maintenance most compasses require.
Take Notes on Your Slate
A slate is an indispensable piece of gear for all diving, but is particularly useful for activities like underwater navigation and photography. It is handy for taking notes and for communicating with your buddy underwater.
For dives where you are practicing underwater navigation techniques, a slate is essential for writing down compass courses, recording natural navigation features of the underwater terrain, and for triangulation, a technique for relocating dive sites.
If you use a flat slate, it can be attached to your buoyancy compensator, or stored in a pocket on your wetsuit or dry suit. Some divers also use round slates, that fit over their sleeves.
To clean a slate after you have written on it, run fresh water on the slate, sprinkle it with an abrasive cleaner, such as Ajax, and rub it with an abrasive sponge. You can also clear any marks on the slate using an ordinary eraser. Either way, the slate is ready to go back in the water immediately.
There are many different types of marker buoys available that are useful in marking a dive site or for practicing your underwater navigation skills. You can also make a simple buoy from items that are commonly available.
The two main categories of commercially available buoys for scuba diving are inflatable buoys and rigid buoys. Both types work well.
Inflatable buoys consist of some type of soft bladder, similar to a balloon. Two advantages of inflatable buoys are that they can be rolled up for storage and transport and inflated only when needed. This type of buoy typically uses a small CO2 cartridge for inflation. A line is fastened to the buoy on one end and to the object to be marked on the other end. This type of buoy requires a bit more maintenance than a rigid buoy and you must purchase a new CO2 cartridge each time you use it.
Rigid buoys are made from either hard plastic or from a non-compressible foam material. A small weight is usually attached to this type of buoy to offset its buoyancy and to serve as an anchor for the bottom end. Rigid buoys do not require any CO2 cartridge and are not prone to puncture. This type of buoy can be a bit more bulky to carry than the inflatable buoy.
To make a simple buoy for marking a dive site from the surface, you can use an old plastic bottle, such as a bleach bottle, nylon line appropriate to the water depth, and a two or three pound weight to anchor the buoy.
A dive light is one of the first accessories that most divers buy after their certification course. They’re not only useful at night, they’re also handy during the day, especially on deeper dives, to help restore the colors filtered out by the water. In California, most lobster divers carry lights even on daytime dives to help them look into holes and crevices while hunting for lobsters.
Dive lights differ from ordinary topside flashlights in that they have waterproof and pressure-proof cases and switches. They are much more rugged and are usually heavier than typical flashlights. Most dive lights today are made from either plastic or machined aluminum.
As battery and bulb technology has improved over the years, dive lights have gotten smaller and smaller. Although you might think a large light would provide more power and light, this isn’t necessarily true. Many of the smaller dive lights available today provide more than adequate light without the need for additional bulk or weight. In most cases, the smaller the light you can use, the better.
Any light you select for night diving should be a non-floating light, or should be easily weighted so that it will sink. Non-floating lights are preferred because if you need to set your light down on the bottom, you don’t want it to float away. If your light floats to the surface, and there is any surface swell or wind waves, you will probably lose your light.
Besides the traditional hand-held light, there are also head-mounted lights that provide a good alternative for night diving. Head-mounted lights are an excellent choice for the underwater photographer or hunter.
Every hand-held dive light should be equipped with a lanyard so that it can be worn on your wrist or attached to your dive gear. However, you must be able to easily remove the light in the event you need to remove it quickly in an emergency.
For night diving, it is recommended that you carry a minimum of two lights. They do not both need to be the same size. One light is used as your primary light and the second is used as your back-up light in case the first one fails.
Light Sticks and Marker Lights
Light sticks are small lights that are designed to attach to a diver’s snorkel or tank valve to identify their location, both on the surface and underwater. Relatively inexpensive Chemical light sticks are available. These devices consist of a heavy walled plastic tube with an inner cylinder of thin glass. The outer plastic tube and the inner thin walled glass tube contain two different chemicals. Chemical light sticks are also known as “cyalumes.”
When the plastic tube is bent, the glass tube breaks and the chemicals mix together. Once the chemicals mix, they emit a bright glow that lasts for several hours. Chemical light sticks can be attached to a diver’s snorkel using waterproof electrical tape, or tied to the tank valve or regulator first stage using a bit of string. In recent years, chemical light sticks have lost their popularity with some divers who feel they are not as environmentally friendly or economical as reusable battery powered light sticks.
Battery powered light sticks are also available and these work well, too. These devices function like a small flashlight, except that the bulb is encased in a plastic shroud that is completely transparent, so the light can be seen from any angle. Battery powered light sticks are reusable by simply replacing the batteries when they lose power or the bulb when it burns out. If you night dive on a regular basis, a battery powered light stick is more economical than a disposable chemical light.
Marker lights or “exit lights” are used to help you relocate the anchor line underwater if you are diving from a boat, or to help you relocate your entry point if you are diving from the beach. There are many different types of marker lights that work well, but it’s a good idea to pick something distinctive, like a strobe or a light with a colored lens, that is easy to identify compared to any other lights that may surround it.
Sound Signaling Devices
For night diving, it is strongly recommended that you carry some type of sound signaling device for getting the attention of the boat operator if you are swept away by a current and your light is not working. This can be a whistle or an air powered horn that works off the low pressure air from your regulator.
Retractors are small spring-loaded mechanical reels that are used to attach dive accessories to your buoyancy compensator. They can be used to attach lights, gauges, slates, and other accessories. When you pull the accessory away from your body, the retractor unspools the line and when you release the accessory, the retractor automatically reels it back in out of your way. Retractors are invaluable accessories for carrying your spare dive light or slate.
Electronic Navigation Aids
The number of electronic aids that can assist you in underwater navigation continues to grow each year and their capabilities are astonishing. The most popular electronic aids are dive tracking devices, electronic compasses, and underwater sonar. For divers who need extremely precise locating capabilities, underwater GPS (Global Positioning System) is also available. Although underwater GPS systems are currently priced out of the range of sport divers, there is no doubt they will be commonly available in the future.
Dive tracking devices are designed to help you relocate the boat or a site that you have marked. The system consists of two devices; a sending unit that emits an electronic signal and an electronic receiver. The sending unit can be hung over the side of the boat, attached to the anchor line, or attached to a wreck or other underwater site. As long as the sending unit is on and has battery power, it gives out a continuous directional signal that can only be picked up by the receiver.
To use the receiving unit, the diver turns on the receiver and swings the unit as he turns in a circle. When the receiver is pointing directly towards the sending unit, the display indicates the correct direction and distance. These are very simple units to use and make underwater navigation extremely simple.
Electronic compasses extend the capability of the ordinary magnetic compass. They perform course calculations for you automatically, and are much more precise than traditional mechanical compasses.
Underwater sonar units are used primarily to measure distances to large objects in limited visibility. These systems are helpful in locating wrecks and reefs.
The Global Positioning System, or “GPS” as it is more popularly known, is a system designed by the U.S. military, using satellites to help locate positions on Earth. A series of satellites in orbit around the earth each send out a signal that can be picked up by GPS receivers. The receivers interpret the signal from each satellite and, by mathematical calculation, provide the location of the receiver.
When people say they own a GPS, they actually mean they own a GPS receiver. GPS receivers are widely used topside, and are quite inexpensive and simple to use. You may have the opportunity during your navigation course to see how GPS operates, particularly if you do any of your diving from a boat.
Some dive boats are still equipped with LORAN, which is an acronym that stands for Long Range Navigational system. LORAN is a good system that has been used for many years, and also provides accurate navigational information. LORAN works in a similar fashion to the GPS system, but the transmitting stations for the LORAN system are located on land rather than in space.
Divers use LORAN and GPS systems in conjunction with a depth finder (fathometer) to position themselves on a dive site. Once the boat is anchored close to the correct spot, depending on the size of the site, you may still need to search for it underwater.
Full-Face Masks and Wireless Communications
Two additional items that can be of tremendous value during many diving activities, but especially in night and limited visibility diving are a full-face mask and wireless communications. The full-face mask is a diving mask that covers the eyes, nose, and mouth. Wireless communications are electronic devices that capture human speech, transmit them through the water as an electronic signal, and reconvert them to a sound you can hear. These two pieces of gear, working together, will allow you to communicate without the need to see your dive partner face-to-face. In certain situations, this type of equipment could save your life.
Full-face masks are not difficult to use, but they do require some additional training before you can use one properly in open water. Ask your instructor about additional training in this specialized equipment.
Since there is no place to stop and ask directions underwater, we hope that this article will be a valued reference to make sure you end up where you wanted to and come back safely.
For more information on the necessary equipment for night diving or to inquire about furthering your diving skills, contact your local SDI Dive Center.
Contact SDI TDI and ERDI