Archive for the ‘Basic SCUBA’ Category

Do you ever see sharks?

Sunday, January 25th, 2009

Yes, all the time. The real question is “are they a danger to SCUBA divers?”

The most common, or plentiful, shark in the Atlantic only grows to a length of 4-5 feet (more commonly seen at 3 ft). They are called sand sharks or Spiny Dogfish. They can be seen around the wrecks either alone, or in small groups. Are they a threat? No. I don’t believe there has ever been an unprovoked attack on humans.

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Cute little shark.

Do we see other sharks? Yes, but far less frequently. Further off shore we will occasionally see basking sharks. These are filter feeders, and no threat, but with their large size, they startle you at first. Other divers have reported seeing Blue sharks, and Mako sharks.

Some things to keep in mind. The incidence of shark attacks on divers is very low. Most shark attacks are in shallow water in the surf zone (beach), with limited visibility. Most divers are in deeper water, with good visibility. In recorded history, there have been only a hand full of attacks in New Jersey. None of these have been on divers.

What do you see diving in New Jersey?

Sunday, January 25th, 2009

The short answer is shipwrecks.

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The Bow of the Chaparra

Here on the east coast we do not have the rocky shore and bottom found on the west coast. Our shore line is mostly sand, and for the most part the bottom is sand also. The continental shelf slopes out for 60+ miles before dropping off sharply. Sand and silt that washes out of our rivers and streams has deposited in this shallow area for thousands of years.

This sand does not provided shelter for fish or secure footing for large plants like kelp. The sand does provide a home for clams, scallops, and sand dollars, but the more interesting areas to dive are the shipwrecks.

There are an estimated 4000-5000 shipwrecks off the coast of New Jersey. (Many people are taken back by that statement.) Keep in mind that we have the port of New York to the north, and the port of Philadelphia to the south. Over the past 300 years there have been thousands of accidents in these waters. Further, during two world wars, the German submarine force spent a significant amount of time trying to stop the flow of supplies from the US to Europe. Many ships were sunk just miles off our beaches.

The older wrecks of wooden ships have been slowly eroded by the forces of nature. Storms, sand, rot, and marine invertebrates have nearly erase them. Still left are the stronger structural beams along with the anchor chain, and machinery used to lift it.

New steel ships quickly fall victim of rust. Many of these ships are now jumbles of steel rubble and hull plates strewn on the sandy bottom. Again stronger or reinforced portions of the ship hold up better with time. Engines, boilers, propellers, and pipes are often recognizable. Metals like coper, brass and bronze stand up better to salt waters corrosive effects.

Even in this state of decay, these wrecks provide shelter for marine creatures. Filter feeders like mussels, sponges and anemones attach to the wreckage for support. Lobsters and crabs burrow under the wreckage for protection. Schools if fish surround the wrecks. Some are looking for shelter, others are looking for food.

How long can you stay underwater on SCUBA?

Wednesday, January 14th, 2009

The final question everyone asks.   Unfortunately, there is no short answer to this question, and the usual response is: it all depends.  After the strange looks, I start to explain some physics and physiology, and lose most people after a few sentences.

Let’s start out by changing the question.  Why do you get out of the water?  Without getting too deep into the physics / physiology and finances, we have one of several reasons:
1)   Limited ability to withstand the temperature drain of water immersion
2)   Limits on the amount of gas we have
3)   Large fish with teeth

Normally, 1 and 2 are the major limiting factors.  When the original question is posed, it is usually referring to our gas limits, so let’s look closer at the factors affecting it.

Without getting too deep into the explanation, lets just use a couple of generalizations.
1)  The deeper you go, the less time you have.
2)   The harder you work (underwater) the less time you have.
3)   Different people consume air at different rates.
4)   The bigger you are, the less time you will have.
5)   New divers will have less time than experienced divers.

Numbers 1 and 2 are immutable facts.  Numbers 3 – 5 are generalizations that vary greatly based on the individual, their physical fitness, and level of skill and comfort in the water.

Just to throw a wrench into the works, we must also consider the size of the tank.   As discussed before, different tanks carry different amounts of gas, and can allow us to stay longer.

Let’s consider an average dive (not working hard), by an average diver at an average depth (60 ft) with the average tank (Aluminum 80).  In general this diver should have gas to dive for about an  hour.

What’s involved in SCUBA training?

Wednesday, January 14th, 2009

This is a another common question along with:  How do you learn to dive?  How long does it take?

There are several Internationally recognized SCUBA training agencies.  There are some differences in the classes, but they all have a similar elements.

Classroom:  Learning ranges from books, to multimedia, to Internet training, but each contains a degree of classroom participation.  Here an instructor can answer any questions, and emphasize safety points.  Often they will stress procedures that me more common in the local diving area.  Yes, there is a test.

Pool:  The first dive experience is in “confined water”, usually a pool. Here we learn to perform certain skills in a safe, controlled environment.  Once mastered we move on to Open Water.

Open Water:   This is usually a lake or quarry.  Here we practice the skills again, and get to swim around and enjoy the dives.   The final dives may be on a boat, depending on the local diving.

I like to think of the class as covering two general areas:  First, how to plan and execute your dive, and second, how to safely handle any problems that may occur during a dive.

The Basic SCUBA class roughly takes 14 hours of classroom, 10 hours of pool, and 5 open water dives.

Once completed, it’s recommended that new divers stay shallow (less than 60 ft) until they feel comfortable with the skills they have learned.  Then they can take additional training to learn the skills necessary to go deeper.

How deep can you dive on SCUBA?

Wednesday, January 14th, 2009

When people first hear about SCUBA diving, many ask this question.   My standard response is “to the bottom”.   While I am joking a bit, unless you’re doing a wall dive, this is usually the case.

Part of the answer depends on the location of the dive: off the coast of New Jersey, the bottom slopes gently for the first 30-50 miles.   Shortly after this we hit the Continental shelf, commonly called the Canyon.   Here the depth drops sharply to several thousand feet.   Obviously our diving is on the gently sloping bottom.

About 3 miles off the beach, the depth averages about 60ft.  After 20-30 miles, there are some great wrecks in 130 ft.   The bottom slope does vary from place to place.   There is narrow trough cut by the Hudson river commonly called the Mud Hole.  It is deeper than the surrounding area, but the outflow of the river makes the conditions more challenging.

The rest of the answer depends on the diver’s experience and training:

Novice divers should stay shallower than 60ft, until they develop the skills and comfort in the water necessary to go deeper.

Advanced divers go between 60 and 130 ft.  At this point they carry additional safety equipment necessary to perform these dives.

Technical divers go beyond the 130 ft range down, sometimes in excess of 300 ft. These divers have spent years training and practicing for these dives.  They carry redundant gear and practice techniques to survive equipment failures.   Many famous shipwrecks are in this range: the Andrea Doria, the U-869, the Black Sunday wrecks including the S.S. Carolina.  These all fall in this range of technical dives.

How deep do I personally go?  Well, I teach Technical Divers.  While I enjoy spearfishing and photography in the 50-130 range, we can often be found diving in the 180-250 range.