Section 3 Flashcards
6 general conditions
Temperature Visibility Water movement Bottom composition Aquatic life Sunlight
Boundary between warmer upper layer of water and cooler deeper layer - name?
Thermocline
Difference between salt and fresh water buoyancy
Fresh water is less dense so has less buoyancy
Water motions that affect me most as a diver
Waves and current
At recreational diving depth water temp changes are most common in…
Fresh water
Surge
Back-and-forth motion caused by waves passing overhead
String surge is dangerous, as it can swing you against rocks
Doesn’t carry you far out to sea but can cause you to loose balance
Adjust to it by diving deeper so it has no effect
Undertow
Water of breaking waves flowing back to sea under incoming waves
Rip current
When water pushed in by waves over a long obstruction, the waves cannot go back that way
It caught, don’t panic and swim parallel to the shore until out
Upwelling
Wind blowing from shore onto the water may displace surface water and cooler, deeper water rises to the surface
Usually associated with good surfing conditions
Boat terminology
Now - front of the boat Stern / Aft - back of the boat Port - left side Starboard - right Leeward - away from Windward - side toward the wind Bridge - where the controls are Head - toilet Galley - kitchen Swim step
Lines in current
Mooring / anchor line - front
Swim line - parallel to boat
Trail line - back
Planning stages
Advanced planning: decision, buddy etc
Preparation planning
Last minute: recheck, tell ppl, food etc
Pre-dive planning: evaluate; align etc
Our of air options
- Ascend
- Alternate air score.
- If 6-9 meters, swim up with an a sound / CESA
- Buoyant emergency ascend
Surface signaling devices
At least two
visual and audio
Diving flags
Standard red flag: divers in the water, generally within 15 meters
Alpha flag (blue): a boat has divers in the water
Boats need to stay 30-60 meters away
