tance, especially if the water is cold. Shore
is always farther away than it appears. A
person can hang on to a fl oating boat or
object much longer than he will be able to
swim. And the person will be able to keep
more of his body out of the water, retaining
body heat. Everyone in the water should be
wearing a life jacket. If not, and the jackets
are still accessible, put them on now.
Stay calm—encourage others to do
the same. You may be able to turn the boat
right side up, bail it, and paddle toward
shore, even using hands for paddles.
If overboard in a river or channel,
swim downstream feet fi rst to avoid potential
head injury.
Boats less than 20 feet long, and built
since 1973, are required to have built-in
floatation. This floatation is to be sufficient
to maintain the boat upright and keep
it from capsizing. There must be enough
buoyancy to keep the head and shoulders
of its crew out of water.
Special techniques for recovery are
often necessary when sailboats swamp or
capsize.
Cold Water Immersion
and Hypothermia
Cold water immersion is dangerous and
may kill you quickly before hypothermia
sets in. Canadian researchers found that
people were dying long before the effects of
hypothermia would have predicted due to
the near instantaneous effect of cold water
immersion.
Four Stages of Cold Water
Immersion
Table 11-3 illustrates the stages of cold
water immersion.
• Stage 1: Initial cold shock occurs in the fi rst
3 to 5 minutes. Your risk is an automatic
gasp refl ex action as soon as immersed in
water under 50°F. If your head is underwater
you can ingest water, drown, or have a
constricted windpipe and suffocate.
• Stage 2: Short-term swim failure occurs
3 to 30 minutes following immersion in
cold water. Manual dexterity, hand grip
strength, and speed of movement can all
drop by 60 to 80%.
• Stage 3: Long-term immersion hypothermia
sets in after 30 minutes, at a rate depending
on water temperature. Cold water robs the
body of heat 25 times faster than cold air.
• Stage 4: Post-immersion collapse occurs
during or after rescue. Once rescued, if
you have been immersed in cold water you
are still in danger from collapse of arterial
blood pressure leading to cardiac arrest.
Most locations in the nothern half of US
have water temperature under 50°F much
of the year.
Be aware that a gasp refl ex happens
upon entering cold water and attempt to
block it; wear a type I or II PFD (raises head
out of water). An automatic infl atable PFD
is preferred since you may not have a chance
to activate it unless you do it in advance.
118 Chapter Three
Table 11-3. Cold Water Immersion
0
5
15
20
25
30
35
Cold
Shock
Swim
Failure
Immersion
Hypothermia
Post-Immersion
Collapse
65
66
67
68
69
70
71
72
73
74
75
76
Tip:
Add refl ective tape
“stripes” to the hull
bottom, near centerline
to aid air and sea search
in the event your boat
is overturned. STAY
WITH THE BOAT!