Night Diving. Why night dive? The preparations. Keeping track of where you are. Handling equipment

Transcription

1 Night Diving Why night dive? The preparations Keeping track of where you are Handling equipment

2 Night Diving The preparations Keeping track of where you are Handling equipment

3 Night Diving Why night dive: 1. Different species of marine life are out at night 2. Marine life is more docile at night and Parrot spin cocoons 3. Marine life is out moving on the reef and in the sand 4. Once in a lifetime viewing of coral spawning during an August night dive 5. Coral polyps come out to feed at night 6. Phosphorescence 7. Basket Starfish open up to feed at night 8. Your attention is more focused by your limited field of view

4 Night Diving Why night dive: 1. Different species of marine life are out at night that you do not see on the reef during the day: Seldom will you see an octopus or squid during the day.

5 Night Diving Why night dive: 2. Marine life is more docile at night and Parrot fish spin cocoons. You can approach marine life much closer at night. Please do not shine your light directly into their eyes. It is so RUDE!

6 Night Diving Why night dive: 3. Marine life is out moving on the reef and in the sand at night:

7 Night Diving Why night dive: 4. Once in a lifetime viewing of coral spawning during an August night dive - if you experience it, you will never forget it!

8 Night Diving Why night dive: 5. Coral polyps come out to feed at night both hard and soft

9 Night Diving Why night dive: 6. Phosphorescence bioluminescence Is seen at night when the water is disturbed. It is largely due to the plankton which is macroscopic free swimming animals (zooplankton), algae, and bacteria that are fed on by fish and crustaceans. Most zooplankton are the larval stage of all marine animals except mammals. The light, a defense reaction, is emitted in response to agitation of being eaten by predators, which would in turn attract the predators of those predators. When a diver disturbs the water (swimming with fins) bioluminescence is stimulated when the water is agitated around the plankton.

10 Night Diving Why night dive: 7. Basket Starfish open up to feed at night Basket Star balled up on the reef during The day Basket Star has climbed Up on a soft coral, Opened and is feeding on plankton moving in the current

11 Night Diving Why night dive: 8. Your attention is more focused by your limited field of view because your beam of light is narrow. You concentrate your attention on the area your light beam illuminates. During the dive you should at times cut off your light and dive by ambient light to take in all of your surroundings under this faint light. Agitate the water and the water will come alive with a light show. If your light is off you can see this effect trail off your dive buddy s fins in front of you.

12 Night Diving The Preparations Dive the area in daylight first. Choose an area with easy entry, calm, shallow water, and prominent landmarks. Remember that orientation and judgment of distance are difficult at night. Arrive before dark, if possible, to re-orient yourself and to prepare your equipment for the dive.

13 Night Diving Keeping Track of Where You Are Shore Dives Is even more important at night. Look back behind you to see the light configuration on shore at your exit/entry point as you enter. These can be two lanterns, the hotel, or street lights on the beach. You could tie an underwater strobe to the exit ladder at about 10 feet. Keep the distance you range from your entry point to a minimum, especially on your first few night dives. Some divers will take additional marker lights and weights or to be tied off, to place along the way to act as crumbs of bread to mark the trail back to the exit point. It is surprising just how far a strobe can be seen in clear Caribbean waters at night.

14 Night Diving Keeping Track of Where You Are Shore Dives Dive boats will sometimes drop a marker light below the boat or tie it to the anchor/buoy line. When diving from a boat at night, YOU MUST COME BACK UP THE DOWN LINE! You should always know where you are in relation to the anchor or where the buoy line is tied. If you have to ascend off the line the current can carry you very far away from the boat and this can put you in a very dangerous situation!

15 Night Diving Float Diving Keeping Track of Where You Are-Float Diving When you are night float diving you must stay with your team leader so the boat will know where you are. Your float will have a marker light on it. You descend as normal, feet first. As you ascend shine your light upward. When you surface hold your light above your head, shinning it down on your head so the boat can see you. Never shine your light at the boat as it will blind the boat captain.

16 Night Diving- Communications To get your buddy s attention, you can: 1. bang on your tank or 2. flash your light back and forth. Once you get their attention, DO NOT SHINE YOUR LIGHT IN THEIR EYES!!! You can use your standard U/W hand signals like this: Slates are excellent:

17 Equipment Dive lights Battery selection Dive light maintenance

18 Equipment Dive Lights At least one waterproof light is required for each diver on a night dive. There are a number of different types of lights and batteries available which suit different purposes. You hold the light while your partner reads the depth gauge and maintains the reference ascent rate. Your buddy holds the light while you make camera adjustments. One holds the bag while the other puts in lobster!

19 Equipment Dive Light When traveling to the Caribbean a small concentrated beam pocket light is all that is needed for the very clear water. You do not need to carry a large, heavy powerful light that is very obtrusive to the sleeping marine life. These lights are also very handy on day dives for looking under ledges and in holes. You attach them to your BC with a quick release (QR) lanyard and put them in your BC pocket. HINT: Put the QR male end on all accessories and the QR female end on the BC.

20 Equipment Battery Selection There are a number of different options for powering a dive light. The two main types of batteries are disposable and rechargeable. Disposable battery lights have a lower initial cost, require limited maintenance, and do not require electrical outlets for charging. LED dive lights offer much longer battery life. They have a higher initial cost, but will save on battery cost.

21 Equipment Dive Light Maintenance The primary cause of a flooded light is an improperly seated or dirty o-ring. You should take extra precaution to seal the light in a well illuminated area. Preferably, do it before you dress to dive. Check and carefully clean the o- ring. Apply a light film of silicone grease to the o- ring. Be sure all wires, grit, or other foreign matter are clear of the sealing surface. Always carry a spare bulb on a dive trip.

22 Equipment continued Marker light on tank valve so you can locate your buddy. It may seem odd, but if your buddy has their back to you and has their light pointing away from you, if they did not have a marker light on their tank, you probably could not see them. Strobe lights to mark your exit point Surface lights will help you locate your exit point from the surface. Look back at these just before you make your entry.

23 Equipment continued Marker light on your tank valve Another essential piece of equipment is a small single-battery marker light, attached to your cylinder valve to make it easy for you and your buddy to keep track of one another. It may seem odd, but if your buddy has their back to you and has their light pointing away from you, if they did not have a marker light on their tank, you probably could not see them.

24 Equipment continued Strobe Lights Strobe lights (i.e compact, high-intensity flashing lights) are available for emergency signaling at the surface. They can be seen for easily under water. Tie one of these off on the ladder at your entry/exit point about 10 feet deep if possible.

25 Equipment continued Surface Lights In addition to dive lights, you will need lights for above water use. These include lights to use for dive preparations as well as surface lights to mark the entry/exit location. Lights to mark the entry/exit point can be anything from a lantern to a flasher.

26 Equipment continued The main idea is that they be distinctive so they won't be readily confused with other lights in the dive area. Be careful to avoid the use of lights which might resemble navigational aids, especially flashing red, green or white lights. Amber or yellow are good alternatives. Strobe lights or a different colored tank marker light can be used on the group leader, on the anchor line, or near a beach exit point for easy identification.

27 Equipment continued Note About Chemical Light Sticks: These are not ecologically sound and should not be used. Battery powered light sticks are much more economical over time.

28 The Night Dive When to terminate a night dive Potential hazards of night diving

29 The Night Dive If possible, pick a calm, familiar, shallow spot for your first dive. Avoid slippery, big surf, and wave-washed rocks at night. Use ladders if at all possible.

30 The Night Dive When to Terminate a Night Dive You should agree to terminate the dive when one of the following occurs: 1. Failure of either diver's primary light source with no backup available 2. When either diver's air pressure reaches 500 psi (in standard cylinders) or a higher pressure, depending on depth

31 The Night Dive 3. If either diver is excessively cold 4. If the divers are separated and cannot find each other underwater 5. The planned end of the dive has arrived.

32 The Night Dive Potential hazards of with night diving include: Disorientation Entanglement Boat traffic Silt, which causes backscatter in light Contacting hazardous creatures Being startled by fast swimming creatures Not finding your way back to the anchor/mooring line and having to surface off the anchor/mooring line. Getting separated from your team leader on a float dive the boat will not know where you are