What is Natural Navigation?:
Natural navigation is a technique for orientation in which a diver uses features of the underwater environment as directional cues. Navigating your way underwater where there are no roads, no signs, no prominent landmarks so to speak is not an easy Scuba diving skill to master. Coupled with other factors playing on a divers mind like buoyancy control, keeping time, depth, conserving air and of course co-coordinating with your buddy, underwater navigation is all the more difficult to keep a track off. Dive sites don’t come with maps and the terrain underwater appears random, irregular and often unpredictable unless you’ve dived the site before a number of times, so this diving skill takes more than a little practice to acquire. Successfully navigating using natural features takes some practice, but is worth learning. Divers must develop situational awareness, consciously observing and taking note of the underwater features around them. Situational awareness may sound easy – what can be simpler than looking around? Yet, the underwater world is filled with so many beautiful distractions (turtles, rays, coral, etc) that it is easy for a diver to lose himself in the details. Divers (especially new divers) are task loaded underwater. Monitoring depth, dive time, buoyancy and tank pressure consumes attention that could otherwise be used to keep track of surroundings. Navigating by natural navigation requires forethought and a conscious decision to pay attention!
Natural Navigation Begins Before a Dive:
The first step in successfully using natural navigation to traverse a dive site is to become familiar with the features of the dive site before entering the water. Decide on some basic landmarks or cues to use for natural navigation based on a map or dive briefing. Once underwater, a diver simply confirms information that he already is familiar with to navigate the dive site. As an example, a diver may view a map of a coral reef before a dive and decide to swim out against the current with the reef on his left, and return to the boat with the current with the reef on his right. Once he has agreed on this course with his buddy, maintaining orientation during the dive becomes easy.
A good diver is always aware of his depth during a dive, but not all divers (even great ones!) realize that depth can be a powerful navigational tool. Many dive sites near shore have a gently sloping floor that deepens as the diver moves away from land. A diver who swims progressively deeper along the bottom knows that he is moving away from the shore, and a diver who swims shallower will realize that he is swimming closer to the shore. If a diver’s depth does not change, chances are that he is swimming parallel to shore. Of course, this is not always the case, and depth changes for a given dive site may vary. A diver should familiarize himself with expected depth variations for a dive site before entering the water.
Structures and Topography:
Perhaps the most obvious form of natural navigation is navigation by underwater features such as reefs, shipwrecks, walls, and other structures. A dive site map is incredibly useful in determining the layout of a dive site and choosing which features to use as navigational tools before a dive. As an example, the map may indicate a coral reef with an edge along a sandy bottom. Decide where to swim in relation to this edge before the dive. Similarly, a diver who plans to dive shipwreck may decide on his route over the wreck ahead of time using structures and features of the wreck. Slopes, dunes, coral walls, and artificial features such as mooring hooks and man-made debris make great references for natural navigation. In the worst case scenario, a diver without a map can make a quick plan by floating on the surface in clear water, observing the reef, and agreeing on a plan with his buddy before the dive.
A constant current may provide a sense of direction underwater – but be warned currents occasionally shift. Divers who use current to provide a sense of direction should begin the dive by swimming against the current and end the dive by swimming with the current. A diver who attempts to swim perpendicular to the current will find that it pushes him away from his original course. He may have difficulty returning along the same route. If using current as a natural navigation tool, be sure to use back-up references, such as depth and structures, in case the current shifts direction.
Sand Patterns, Sun and Shadows:
In dive sites with water movement, ripples may form in the sand. These patterns generally run parallel to shore, and can help to provide a directional reference. During morning and late afternoon the position of the sun (and the shadows cast by the sun) can provide an additional reference. Of course, this doesn’t work around midday, when the sun is directly overhead, or on very long dives during which the sun may change position.
Divers with good situational awareness use a combination of many of the above navigational techniques to maintain orientation during a dive. However, remember that your chosen visual references may look unfamiliar when viewed from the opposite direction upon return. Periodically look back at the return path to create a series of mental “snapshots” which will help you recognize you return path.
10 Tips for improving your underwater navigation skills:
1. Plan Ahead
An important part of underwater navigation is gathering as much information about the location before hand. Collect information about the expected scenario like large coral formations, rocks, drop offs, sandy patches, wreck size, and so on from experienced divers or dive operators in the area.
Map out the dive site on dive slate before you go and maybe chalk out an intended dive plan in the direction you want to go in for reference underwater. Sometimes just doing that helps you visualize the map in your head and you may not need to use the map. A good idea is once you’re diving the site you can note certain landmarks on your map to find your way back easily.
3. Know where your dive boat is
Just like a car in a parking lot you need to make a note of where your dive begins, so as to return to the right spot. Make a mental note of the surroundings, any particular rock or coral formations where you first descend. Pay attention to the direction you can see the sun and remember what your dive boat looks like from under especially if there are more than one in the vicinity.
As a minimum, a diver must carry an underwater compass for navigation. Buy a simple compass and learn the correct way to use it. Take it on guided dives to get the hang of using it before heading off on your own.
5. Setting the bezel
Before beginning a dive you should set the bezel of your compass to point you to the direction dive boat and in case of shore diving to the shore. In this case once the bearing is set it shouldn’t be changed during the dive and to return, one simply rotates himself in the opposite direction.
6. Measuring distance
A rookie mistake when it comes to underwater navigation is noting down the direction but completely losing track or not measuring distance. It’s important to know exactly how far you have swum out and in what direction in order to return. One way of doing this if you are a consistent swimmer is by time or even air consumption. It may not be as accurate as counting fin strokes as you are thought in your course but it sure beats spending most of your dive concentrating on counting rather than the surroundings.
7. Use natural directional indicators
When diving in good clear water conditions and in the day, the sun is a great natural compass. For example during a morning dive you know the sun will be in eastern direction while for afternoon dives the sun indicates west.Sand ripples caused by currents too are good directional indicators as they always run parallel to the shore. The deeper imprint of the ripple, the nearer to the shore you are.
8. Don’t use currents as indicators
Don’t rely on currents to tell you in which direction you are heading. Currents can twist and turn around undersea objects thereby leading you astray.
9. Trust your instruments
If there is a discrepancy between what you feel and what your dive compass is telling you, go with the compass. Be sure that it is working properly before the dive and that there is no interference from undersea objects like shipwrecks or anything that can be magnetic however.
Practice using your compass on land. Do squares, rectangles, set headings and reciprocals, note bearings, in short perfect your compass skills on land. Then on guided dives, practice your own navigation rather than blindly following the dive master, it’s a great feeling to successfully hit your mark when you try. Make it a habit to jot down things like bearings, landmarks, directions, times on your dive slate throughout your dive. With time and practice you’ll be a pro at navigating during a dive and even the fish will be seeking your instructions.
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