Download Boating Skills and Seamanship

Chapter
12
Weather And Boating
Boating Skills And Seamanship
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
1
Lesson Objectives
Boating Skills And Seamanship
•
•
•
•
•
Weather information sources
Basic storm patterns
Storm forecasting and precautions
Go, no go decision making
A personal weather equipment and
equipment check list
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
2
Weather Information
Boating Skills And Seamanship
• What are some of
the sources you
can check for
weather
information?
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
3
Wind and Boating
Boating Skills And Seamanship
• What can happen to a vessel
caught in a storm?
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
4
Winds and Boating
Boating Skills And Seamanship
•
•
•
•
•
•
•
Storm surge
Swells
Breaking waves
Wave height
Wave frequency
Waves in shallow water
Fetch
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
5
Winds and Boating
Boating Skills And Seamanship
• Storm surge is caused by raising sea levels
in the low pressure areas around the
storms. If these elevated sea levels reach
shore they will add to high tide levels.
• Swells are waves coming from a distant
disturbing force resulting in decreased
heights and longer wave lengths.
• Breaking waves can occur on navigable
waters as well as on shore. Shallow Water
slows bottom of wave, top then spills over &
breaks. Released energy can be dangerous.
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
6
Winds and Boating
Boating Skills And Seamanship
• Wave height is dependent on wind strength,
duration, and fetch. Wave height is
classified (e.g. 3’ to 5’) by the range of wave
heights which will occur 70% of the time.
• Wave frequency indicates gradient of wave
face
• Fetch is the distance over which the wind
blows uninterrupted on the water surface.
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
7
Winds and Boating
Boating Skills And Seamanship
Beaufort Wind Scale
Table 12-1
Beaufort
Number
Wind
Description
Mean Wind
Speed
Equivalent
(knots)
Sea
Conditions
Mean
Wave
Height
meters feet
0
Calm
≤1
Sea is like a mirrow.
1
Light air
1-3
Ripples without foam crests.
5
Fresh breeze
17-21
moderate waves with a more pronounced
long form; many whitecaps. A little spray.
2
6.6
41-47
High waves; crests begin to tumbler;
dense streaks of form. Spray affects
visibility.
7
23
64 +
Seas tumultuous. The air is filled with
foam. The ocean is totally white with
driving spray. Visibility seriously reduced.
9
12
Strong gale
Hurricane
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
Copyright Hal Roth, 2006, reprinted with permission
-
-
0-0.1 0-0.3
14 46
8
Understanding
Weather
Boating Skills And Seamanship
• Weather and heat
• Land heats faster than
water
• Land and sea
breezes
Reprinted with permission from
Gary Jobson’s Championship Sailing by Gary Jobson
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
9
Understanding
Weather
Boating Skills And Seamanship
• The Coriolis
Force
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
10
Understanding Weather
Boating Skills And Seamanship
• The air is warmed at the equator, rises, goes north
and south, is cooled and falls again. When it
reaches the earth, it goes north and south again,
warms up, rises and repeats the cycle twice more
resulting in three “doughnut” shaped air masses
circulating on each side of the equator.
• The Coriolis Force, which turns moving masses to
the right in the Northern Hemisphere and left in the
southern, results in continuous wind patterns
around the globe.
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
11
Understanding
Weather
Boating Skills And Seamanship
• Temperature and
Humidity
• Moisture and energy
• Air masses
• High pressure system contain
cool, dense, dry air.
• Low pressure system contain
warm, thin/rare, moist air
which is energy laden
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
12
Understanding
Weather
Boating Skills And Seamanship
• Lows
• Highs
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
Adapted from Boater’s Bowditch by Rickard K. Hubbard
13
Understanding
Weather
Boating Skills And Seamanship
• Why do we have inclement weather
with a low pressure system?
• A low pressure air mass is unstable, i.e., it is less
dense, or lighter than the surrounding air mass
and therefore easily displaced.
• Low pressure air rises & cools, releasing
moisture and energy
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
14
Understanding
Weather
Boating Skills And Seamanship
• Buys Ballot’s Law
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
15
Understanding
Weather
Boating Skills And Seamanship
• Fronts
• Warm front
• Cold front moving
• Stationary front
warm front
cold front
stationary front
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
16
Cold Fronts
Boating Skills And Seamanship
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
17
Understanding Weather
Boating Skills And Seamanship
• Cold Fronts
•
•
•
•
Air Cooler Behind Than Ahead
Fast Moving
Can Create Violent Weather
When Passes
• Pressure Rises Abruptly
• Temperature Falls
• Relative Humidity Decreases
• Wind Shifts Direction
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
18
Warm Front
Boating Skills And Seamanship
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
19
Understanding Weather
Boating Skills And Seamanship
• Warm Front
•
•
•
•
•
•
Air Warmer Behind Than Ahead
Slow Moving
Non-Violent Weather
Nighttime Fog Frequent
Can Have Long Periods Of Rain
When Passes
– Little Pressure Change
– Little Temperature Change
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
20
Understanding
Weather
Boating Skills And Seamanship
• Clouds and Fronts
• Who recalls the three types of clouds and
characteristics of each that accompany fronts?
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
21
Cloud Identification
Boating Skills And Seamanship
• Cirrus
• thin high-level made of ice crystals
• Stratus
• Layered, flat
• Cumulus
• Fluffy, White, Fair Weather Clouds
• May Grow To Cumulonimbus (nimbo/nimbus =
rain clouds)
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
22
Cloud Families
Boating Skills And Seamanship
• High - Cirriform
• Cirrus, Cirrocumulus, Cirrostratus
• Mostly Ice – No Precipitation
• Middle - Alto
• Altostratus, Altocumulus, Nimbostratus
• Mostly Water
• Low
• Stratus, Stratocumulus, Cumulus
• Mostly Water
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
23
High Clouds
Boating Skills And Seamanship
• Cirrus
• Mares’ Tails
• Cirrocumulus
• Mackerel Scales
• Cirrostratus
• Like A Sheet Or Veil
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
24
Cirrus (Ci)
Boating Skills And Seamanship
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
25
Cirrocumulus (Cc)
Boating Skills And Seamanship
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
26
Middle Clouds
Boating Skills And Seamanship
• Altostratus
• Mid-level, Layered
• Altocumulus
• Cumulus Clouds Gathered In Layers
• Cumulonimbus
• Rain Clouds
• May Develop Into Thunderheads (Towering
Cumulus)
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
27
Cumulus
Boating Skills And Seamanship
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
28
Towering Cumulus (Tcu)
Boating Skills And Seamanship
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
29
Cumulonimbus (Cb)
Boating Skills And Seamanship
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
30
Altocumulus (Ac)
Boating Skills And Seamanship
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
31
Low Clouds
Boating Skills And Seamanship
• Stratus
• Low Layers Of Solid Cloud Cover
• Nimbostratus
• Rain Clouds
• Intermittent Or Steady Rain
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
32
Stratocumulus (Sc)
Boating Skills And Seamanship
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
33
Stratus (St)
Boating Skills And Seamanship
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
34
Understanding
Weather
Boating Skills And Seamanship
• Weather clues from clouds
• Cold front clouds
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
35
Understanding Weather
Boating Skills And Seamanship
• A cold front is comprised of dense air
and as it moves it pushes all the air in
front of it aloft where it cools forming
cumulous nimbus clouds and heavy
rains
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
36
Understanding
Weather
Boating Skills And Seamanship
• Weather clues from clouds
• Warm front clouds
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
37
Understanding Weather
Boating Skills And Seamanship
• High thin cirrus clouds ahead of a
warm front.
• A warm front climbs over the colder air
in front resulting in stratus clouds and
a drizzling rain for an extended period
of time.
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
38
Understanding
Weather Pg 330
Boating Skills And Seamanship
•
•
•
•
•
•
Approaching low
Approaching warm front
Passing warm front
Within warm sector
Approaching cold front
Passing cold front
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
39
Understanding
Weather
Boating Skills And Seamanship
• Fog
• Conditions favoring fog formation
• Radiation fog
• Clear sky, little or no wind, temp & dew point
about equal, burns off quickly
• Advection fog
• Caused by warm, moist air blowing over cold
body; light wind < 15mph; slow to burn off
• Predicting fog
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
40
Fog Precautions
Boating Skills And Seamanship
• What precautions must be taken in
fog?
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
41
Non-Frontal Weather
Boating Skills And Seamanship
• Thunderstorms
• Stage one
• Stage two
• Stage three
Reprinted with permission from
Boater’s Bowditch by Richard K. Hubbard
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
42
Thunderstorms
Boating Skills And Seamanship
Tornadoes
Lightening
Microbursts
• Waterspouts
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
43
Non-Frontal Weather
Boating Skills And Seamanship
• What should you do if you are caught
in a thunderstorm?
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
44
Thunderstorm
Boating Skills And Seamanship
• Get to shore & let it pass
• At sea
•
•
•
•
•
•
•
•
•
Put on life jacket
Close ports and hatches
Note location of vessel
Reduce speed
Keep sharp lookout
Head into wind
Approach waves at 45 degree angle
Stay low in boat
Keep away from metal objects
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
45
Non-Frontal Weather
Boating Skills And Seamanship
• Tropical Weather
• Tropical Depression
• Wind Up To 34 Knots
• Tropical Storm
• Wind 35 - 64 Knots
• Hurricane
• Wind 65 Knots Or More
• Also called
– Typhoon
– Cyclone
– Willy-Willy
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
46
The Go, No-Go
Decision
Boating Skills And Seamanship
• What are some of the considerations
for making a decision to go or no-go?
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
47
The Go, No-Go Decision
Boating Skills And Seamanship
•
•
•
•
•
•
•
•
•
•
Is weather suitable for cruise?
Necessary equipment for safe operation
Crew confidence
Proper food and necessities
Getting weather info.
Boating and safety knowledge
Navigation ability
Back up plan
Float plan
Comfort level
Copyright 2007 - Coast Guard Auxiliary Association, Inc.
48