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587a7a0 Nov 14, 2016
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Night Diver

Knowledge Review - Part 1

General recommendation for using new or unfamiliar equipment is to use it during the day to become familiar with it.

Three uses for marker lights and where they are attached for those uses:

  • to mark each diver - attached to snorkel or cylinder valve
  • to alert boaters of presense - attach dive boat or surface float
  • to mark line - attach several along length using different colors for safety stops

When considering and evaluating a potential dive site for night diving, it is preferable to avoid an unfamiliar site at night.

Six environmental conditions you should avoid when night diving:

  • moderate to high surf
  • moderate to strong currents
  • bad visibility
  • thick kelp, fishing net, or anything that can entangle
  • heavy surge
  • overhead environments

Four general night diving planning considerations:

  • prepare your equipment in the daylight
  • eat a few hours before the dive
  • dive with familiar buddies
  • bring a friend

If you experience stress, light failture, buddy separation or disorientation while night diving

  • Stress: chill
  • Light failure: stop, switch to backup, and abort the dive
  • Buddy separation:
    • stop, shine light down and away, and look for other lights
    • rise slightly, and cover your light
    • shine your light straight out and rotate to get their attention
  • Disorientation:
    • hold on to reference: line, buddy, yourself, watch your bubble or look at bottom
    • check your compass, look for natural navigation clues

Briefly describe the procedures for entering the water at night from a boat and from shore:

  • turn on primary light and fasten to wrist or clip
  • check entry area with light for obstructions
  • if entering through surf, time entry with lull in the waves, check frequently with light
  • enter as you normally would
  • stay close to buddy and do not shine light in their eyes

Proper techniques for descending or ascending at night as to avoid disorientation and undue stress:

  • use bottom or line as reference
  • stay with your buddy
  • use your light to watch ahead
  • descend head-up
  • mark your safety stop

Methods of communication while night diving:

  • get buddy attention by rapping cylinder, waving light, or gently touching buddy
  • signal by shining your light on signal hand
  • if far away, signal with light: circle = ok, side-to-side = attention

Navigational techniques used to avoid disorientation and loss of direction while night diving include paying attention to:

  • water movement: current and surge
  • sand or mud ripples
  • rock/reef formation
  • depth
  • light

Knowledge Review - Part 2

Do not make overhead environment dives at night!

Night diving considerations that apply to your personal dive equipment include:

  • clearly marking your alternate air source
  • making sure you can find your BCD low-pressure inflator
  • extra thermal protection
  • self-illuminating instruments
  • whistle and visual signals

It's important to carry at least two dive lights because they aren't as consistently reliable and may fail.

Advantages and disadvantages of non-rechargeable batteries in dive lights:

  • have long burn time
  • have few maintenance considerations
  • may leak and damage light
  • not environmentally friendly

Advantages and disadvantages and rechargeable batteries in dive lights:

  • cost less to use in the long run for frequent night dives
  • require more care than disposable batteries
  • may burn longer or shorter than disposables depending upon the type

Maintain a dive light by:

  • dunking in fresh water immediately after use
  • drying lights
  • removing batteries
  • inspect battery contacts and clean them with pencil eraser
  • inspect, clean, and lubricate o-rings

If your dive light floods:

  • turn it off and switch to backup light
  • exit water and open light ASAP, very carefully, away from people
  • pour out water
  • discard battery
  • rinse interior/exterior with fresh water
  • dry with hair dryer

Three uses for marker lights:

  • to mark each diver
  • to alert boaters of presence
  • to mark line

Underwater strobes can be used to spot a float, reference light or boat from a long distance. You can also put them above water on float or boat for easy identification at surface.

Two uses for surface support lights:

  • to assist you in gearing up/down
  • to keep you oriented to entry/exit points

Be courteous while night diving by keeping noise to a minimum when gearing up/down. Underwater, do night shine you lights in divers' eyes.