Swiftwater Flashcards
4 basics of hydraulics
volume, gradient, obstruction, constriction
breaking wave
A large wave that has a foam pile on top. A
breaking wave is similar to a hydraulic in that it can stop and flip a boat, but generally it will not hold a boat or swimmer
strainer
A tree or any obstruction that water passes through and objects (including people) do not.
sieve
A formation of rocks that allows water to pass through but not objects.
Downstream Safety
It is important to contain the rescue scene and protect the
rescuers and/or victim from being lost downstream
Upstream spotter
person has the job of alerting the rescue team of any debris or hazards that are entering the rescue scene. This person must also be ready to stop any other river users from floating into the scene.
Phase of rescue
L– locate
A– access
S– stabilize
T– transport
In order to locate a person on the river, a two crucial pieces
- Time last seen
2. Point last seen
parameters of a Hasty Search.
- If possible, spotters should be sent to the furthest distance downstream the victim could float.
- Then, two water-based crews should search each shoreline fast for any obvious evidence of the lost person.
- Two land-based crews should search each shoreline fast for obvious evidence
Humans lose their body heat ___times faster in water than in air.
25
Survival of submersion is affected by three
conditions:
- Duration of submersion (shorter period the
better)
2 Temperature of water (colder the better)
3 Age of victim (younger the better)
Polypropylene
dynamic, floating, 1000-2000 lb. breaking strength, exposed core is black, not adequate for tensioning!!
Spectra/Dyneema
static, floating, 3000-4000 lb. breaking strength, exposed core is generally white, can be used as a tensioned line
Foot entrapment #1 priority
stabilize the entrapment victim as
quickly as possible.
In extracting an entrapped victim, most
people come out of entrapments….
the same way they went in
1st three opions for entrapments
Step 1: Can you throw them a rope? Step 2: Can you access from downstream and get hands-on stabilization? Step 3: Can you get them a stabilization line?
4 types of holes
smiling, frowning, diagonal, horizontal
Hole is
caused by water flowing over an obstacle (rock, ledge, dam, etc) and creating a reversal current
intensity of a hole: 4 factors
width of hole, the steepness of the drop, the depth of the hole, and the length of the backwash
swiftwater is water flowing faster than ___ and over ___ ft occurring in ____
1.5mph
2
natural watercourse
12 swiftwater principles
- Priorities: self, team, victim
- wear PPE
- keep rescue plan simple
- have backup plans
- deploy multiple downstream rescuers
- deploy upstream spotter
- dont stand inside the rope bight or on the downstream side of a tensioned line
- dont tie a rope to rescuer
- dont stand in water above your knee
- dont tension a line 90 to the current
- once victim is contact, dont lose them
- dont count on the victim helping
laminar flow
layered downstream flow of the river’s main current. The layer in the center just below the surface moves
the fastest, while the side and bottom layers
are slowed somewhat by friction.
helical flow
corkscrew flow between main current and shore
smiling hole
Strong reversal in center with downstream
current on either side. Exit to the sides.
frowning hole
strongest reversal is side to side. Trying to exit to the side results in being pushed back to the center. Exit is
down beneath the surface.
current vector
Strongest laminar flow in a channel. May not be parallel to shoreline
ferry angle
45 degree angle to current vector
if the victim doesnt have a PFD on…
get one to them
max length for live bait rope
75ft
____ inches of water can make you lose control of a vehicle
6 inches
___ ft of water will carry most cars away
2
Never approach a vehicle from
the upstream side. could get pinned or sucked underneath
If the passengers are still inside the vehicle and there
is a substantial cushion (water speed 7 mph or 8 ft per sec) of water on the upstream side of the vehicle…
DON'T punch the window on the downstream side since drastic decompression can blow all the glass explosively and you may lose the victims as well.
Options for low head dam rescue
throw bag
line with rescue buoy across river
inflated fire hose
two boats connected by safety line: one close to the hydraulic, one 100-150ft down stream to pull other boat out
water speed doubles, force increases __x
4
Eddy
horizontal reversal of water flow upstream caused by low pressure behind an obstacle
eddy fence
obvious line in river where water flows in the opposite direction at each side
Hole (hydraulic)
vertical reversal of water flow where the pressure of the current falling over a gradient (rock) causes water to loop back causing some water to flow downstream, some back to the base of the gradient
PFD have an min of ___lbs of float
15.5
The average car will float for ___ seconds
45
Electrical in a submerged call will probably still work
T/F
T
Car on a hard surface,sideways in the current is likely/unlikely to roll
likely
cars on soft surface are likely to
settle because each tire will create an eddy, scooping out soil
victims on the roof of a car should
high side
not move after they are on the high side
foam piles are ___ to ___% air
40-60
most injuries occur
within 10 ft of shore
once a drowning victim goes “wind down” behavior, rescuer has ___ secs to get to the victim
10-15
weight of 180-200lb male in water
7-11lbs
