Expert Scuba

All of these are very good questions to ask. Quite often newly certified divers wonder if they are ready to take my Advanced class and my response is ... by all means ... sign up! I always welcome new divers into my Advanced class. Being asked to help a new diver in continuing their education is a joy and an honor for any instructor.

Brand new divers tend to be eager to learn, and that is good. I enjoy opening new doors for their interests to blossom. I like to think I do so in an encouraging and helpful way. In no way is an Advanced class going to make a person an instant expert in any area. It does, however, give them additional knowledge on which to build upon and enjoy our sport.

A NAUI Advanced Course includes at least six dives in different areas. Depending on where you are taking the course, the types of dives will vary. When completing an Advanced class in the ocean your training will likely include a non-penetration wreck dive and/or a drift dive.

When I teach an Advanced class locally, I usually begin with a buoyancy clinic. We discuss and correct issues such as proper weighting, proper trim in the water, proper finning techniques, and all around general comfort in the water.

All too often beginning divers are over-weighted for their evaluation dives and don't realize how much more efficient they would be with the proper amount of weight, as opposed to what they may have carried previously. Instructors often over-weight so students can stay comfortably on the bottom or on a training platform to practice their basic skills without floundering around. However, getting in the habit of wearing too much weight will hinder good buoyancy skills, and that in turn makes your air consumption worse.

By wearing the correct amount of weight a new diver will find neutral buoyancy much easier to achieve. When you use less air in your BC to remain neutrally buoyant, you have more air to breathe! By being more comfortable in the water your breathing rate will slow down. Better buoyancy + slower breathing = better air consumption + longer bottom time!

After everyone in the class has a grip on neutral buoyancy and comfort, we move on to using certain tools. We discuss and demonstrate the use of lift bags and safety markers. I explain that you should never attempt to bring up an object that weighs more than your weightbelt without the use of a lift bag. I explain the features of the lift bags and the function of each feature. I show the students a couple of styles of safety markers. We discuss the pros and cons of each. Once we have completed the workshop we put the lift bag to use! Any tools you might want to use underwater require practice underwater.

On the third dive we put all the components of the first dive into use. We plan a dive to find out what each diver's air consumption rate is. I generally plan the dive to 35 feet, spending 20 minutes at depth, then doing a safety stop at 15 feet for three minutes. Each diver is responsible for remembering his/her own air pressure used. The diver makes note of starting tank pressure and the remaining pressure at the end of 20 minutes at depth.

I explain converting pressure to cubic feet of air used, then calculating air consumption based on the dive. Let's use an aluminum 80 cubic foot tank as an example. Aluminum 80s have a working pressure of 3,000 psi. Divide the tanks volume (80) by working pressure (3000) to find the cubic feet per psi. To find out how many cubic feet of gas used during the designated dive time, multiply the number by the psi used. To find out how much air would have been used at the surface we then divide that number by 2, since 35 feet in fresh water is very close to 2 ATAs. Divide this number by 20 minutes and the answer gives you your air consumption in cubic feet.

Example: 80 cu ft tank, 1000 psi used, 35 feet for 20 minutes.
80/3000 = 0.0266666 X 1000 = 26.6666/2 = 13.3333/20 = 0.666665
This diver's surface air consumption rate would be .66 cubic feet per minute.

New divers often learn their surface air consumption rate is anywhere between .66 and 1.1 cubic feet per minute. The more you dive and the more comfortable you become, the less air you will consume. Knowing how much air you consume on the surface will allow you to better plan your dives. Knowing planned depths and tank volumes, you can figure out roughly how much time you can spend diving.

Next we plan and conduct a night dive. The first rule of night diving is to dive the site in the daytime first. Familiarize yourself with the entry, the exit, and any points of interest you care to see and explore. I demonstrate light signals. I remind everyone to keep your light beam out of everyone's eyes. Acclimating to darkness takes 20 minutes or so, however, losing it takes just a split second! I often add a little challenge to the dive by taking students to a local river. This way they get to familiarize themselves with current, too.

The deep dive is next. We spend time reviewing dive tables. Since the students will also be doing a navigation dive later in the day, they plan both dives and a surface interval based on the information I supply about the dives.

Quite often I conduct the Advanced class at Loch Low-Minn quarry in Athens, Tennessee. The deepest section of the quarry is roughly 80 feet and not often vey clear. Often the visibility is good, but the ambient light is lacking, due to the algae bloom in the shallower water. One thing everyone will discover is what a thermocline is! And there are things to see: Recently 70+ paddlefish were released in the quarry, and they prefer the deeper water, so I suspect we'll be meeting them during future deep dives there.

Last, but certainly not least, is the navigation dive. This can be challenging, so I save it for last. Successful navigation begins with proper planning of the dive and clarifying the role of each member of the dive team. We introduce indirect read and direct read compasses to the students. We discuss all the features of compasses and demonstrate how to use them. They perform a few patterns on land, then donn gear for surface skills.

We explain the usefulness and importance of measuring distance underwater. Each student then follows a measured line and counts his/her kick cycles. They do this twice and find an average. Each student is given a direction and a distance and asked to do a reciprocal heading back to their starting point. Once this is done, they are asked to swim a square search pattern using kick cycles and the compass in returning to where they began.

And then the fun begins! Each team prepares for their navigation dive, discussing each person's responsibilities. My navigation course is rather unique in that there are no signs of the course from the surface!

A rescue is a required dive for the Advanced certification. Since I include a detailed rescue in my beginning class, I do not dwell on it, but we do discuss proper techniques and practice being victim and the rescuer.

The exact sequence for a successful rescue includes locating the victim, shaking them to see if they respond, and assume control by placing your knees on either side of the victims scuba tank. As you remain above the victim, steadying yourself on their back, be sure to maintain an open airway by cradling his/her chin in your right hand and aiming their face towards the surface. Attempt to bring the victim up by inflating his/her BC. If the victim's scuba tank is empty, you must use your own BC to begin the ascent. Remember the rate of ascent is crucial - no faster than your smallest exhaled bubbles! Once on the surface, call for help, then check the victim's airway, breathing and circulation. Get the victim out of the water and out of his/her gear, lay him/her flat on his/her back with feet elevated. Call Diver's Alert Network (DAN) at 1-919-684-8111. Do what you can to make the victim comfortable, maintain life support and wait for further instruction and assistance.

And that, my friend, is my Advanced Class! Care to join us?

Posted by Carol at November 6, 2006 04:08 PM

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