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wind is greater than the current.
Unlike landplane operations at airports, many other
activities are permitted in waters where seaplane
operations are conducted. Seaplane pilots encounter a
variety of objects on the water, some of which are
nearly submerged and difficult to see. These include
items that are stationary, such as pilings and buoys,
and those that are mobile, like logs, swimmers, water
skiers, and a variety of watercraft. Before beginning
the takeoff, it is a good practice to taxi along the
intended takeoff path to check for any hazardous
objects or obstructions.
Make absolutely sure the takeoff path ahead is free
of boats, swimmers, and other water traffic, and be
sure it will remain so for the duration of the takeoff
run. Powerboats, wind-surfers, and jet-skis can
move quickly and change direction abruptly. As the POUNDS THRUST OR DRAG
KNOTS 20 40 60 80
"Hump"
Water
Drag
Propeller
Thrust
Figure 4-14. This graph shows water drag and propeller
thrust during a takeoff run.
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4-12
seaplane’s nose comes up with the application of full
power, the view ahead may be completely blocked by
the cowling. Check to the sides and behind the seaplane
as well as straight ahead, since many watercraft
move much faster than the normal taxi speed and may
be passing the seaplane from behind. In addition to the
vessels themselves, also scan for their wakes and try to
anticipate where the wakes will be during takeoff.
Operators of motorboats and other watercraft often do
not realize the hazard caused by moving their vessels
across the takeoff path of a seaplane. It is usually better
to delay takeoff and wait for the swells to pass rather
than encountering them at high speed. Even small
swells can cause dangerous pitching or rolling for a
seaplane, so taxi across them at an angle rather than
head-on. Remember to check for other air traffic and
make any appropriate radio calls.
Be sure to use the pre-takeoff checklist on every takeoff.
All checks are performed as the seaplane taxies,
including the engine runup. Hold the elevator control
all the way back throughout the runup to minimize
spray around the propeller. If there is significant wind,
let the seaplane turn into the wind for the runup. As
r.p.m. increases, the nose rises into the plowing position
and the seaplane begins to accelerate. Since this is
a relatively unstable position, performing the runup
into the wind minimizes the possibility of crosswinds,
rough water, or gusts upsetting the seaplane. Waste no
time during the runup checks, but be thorough and precise.
Taxi speed will drop as soon as the power is
reduced.
Water rudders are normally retracted before applying
takeoff power. The buffeting and dynamic water pressure
during a takeoff can cause serious damage if the
water rudders are left down.
As full power is applied during takeoff in most seaplanes,
torque and P-factor tend to force the left float
down into the water. Right rudder pressure helps to
maintain a straight takeoff path. In some cases, left
aileron may also help to counter the tendency to turn
left at low speeds, by increasing drag on the right side
of the seaplane.
Density altitude is particularly important in seaplane
flying. High, hot, and humid conditions reduce engine
power and propeller efficiency, and the seaplane must
also attain a higher water speed in order to generate the
lift required for takeoff. This increase in water speed
means overcoming additional water drag. All of these
factors combine to increase takeoff distances and
decrease climb performance. In high density altitude
conditions, consider not only the length of the water
run, but the room required for a safe climbout as well.
The land area around a body of water is invariably
somewhat higher than the water surface. Tall trees are
common along shorelines, and in many areas, steep or
mountainous terrain rises from the water’s edge. Be
certain the departure path allows sufficient room for
safe terrain clearance or for a wide climbing turn back
over the water.
There are specific takeoff techniques for different
wind and water situations. Large water areas almost
always allow a takeoff into the wind, but there are
occasionally circumstances where a crosswind or
downwind takeoff may be more appropriate. Over the
years, techniques have evolved for handling rough
water or a glassy smooth surface. Knowing and practicing
these techniques not only keep skills polished so
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