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and seeing that they have fastened their seatbelts. The
passenger briefing should include procedures for evacuation,
the use of flotation gear, and the location and
operation of regular and emergency exits. All passengers
are required to be familiar with the operation of
seatbelts and shoulder harnesses (if installed). When
the engine is primed and ready to start, the pilot leaves
the cockpit, shoves off, returns to the pilot’s seat,
quickly turns on the master switch and magnetos, verifies
that the propeller area is clear, and starts the
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4-4
Use the idling or displacement position for most taxiing
operations, and keep speeds below 6-7 knots to
minimize spray getting to the propeller. It is especially
important to taxi at low speed in congested or confined
areas because inertia forces at higher speeds allow the
seaplane to coast farther and serious damage can result
from even minor collisions. Cross boat wakes or swells
at a 45° angle, if possible, to minimize pitching or
rolling and the possibility of an upset.
PLOWING POSITION
Applying power causes the center of buoyancy to shift
back, due to increased hydrodynamic pressure on the
bottoms of the floats. This places more of the seaplane’s
weight behind the step, and because the floats
are narrower toward the rear, the sterns sink farther
into the water. Holding the elevator full up also helps
push the tail down due to the increased airflow from
the propeller. The plowing position creates high drag,
requiring a relatively large amount of power for a
modest gain in speed. Because of the higher r.p.m.,
the propeller may pick up spray even though the nose
is high. The higher engine power combined with low
cooling airflow creates a danger of heat buildup in the
engine. Monitor engine temperature carefully to avoid
overheating. Taxiing in the plowing position is not
recommended. It is usually just the transitional phase
between idle taxi and planing. [Figure 4-6]
PLANING OR STEP POSITION
In the planing position, most of the seaplane’s weight
is supported by hydrodynamic lift rather than the
buoyancy of the floats. (Because of the wing’s speed
through the air, aerodynamic lift may also be supporting
some of the weight of the seaplane.)
Hydrodynamic lift depends on movement through the
water, like a water ski. As the float moves faster
through the water, it becomes possible to change the
pitch attitude to raise the rear portions of the floats
clear of the water. This greatly reduces water drag,
allowing the seaplane to accelerate to lift-off speed.
This position is most often called on the step. [Figure
4-7]
There is one pitch attitude that produces the minimum
amount of drag when the seaplane is on the step. An
experienced seaplane pilot can easily find this “sweet
spot” or “slick spot” by the feel of the floats on the
water, but the beginning seaplane pilot usually needs
to rely on gauging the position of the nose on the horizon.
If the nose is considerably high, the rear portions
of the floats contact the water, drag increases, and the
Figure 4-5. Idling position.The engine is at idle r.p.m., the seaplane moves slowly, the attitude is nearly level, and buoyancy supports
the seaplane.
Figure 4-6. Plowing position.
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4-5
seaplane tends to start settling back into more of a
plowing position. If the nose is held only slightly
higher than the ideal planing attitude, the seaplane
may remain on the step but take much longer to accelerate
to rotation speed. On the other hand, if the nose
is too low, more of the front portion of the float contacts
the water, creating more drag. This condition is
called dragging, and as the nose pulls down and the
seaplane begins to slow, it can sometimes feel similar
to applying the brakes in a landplane.
To continue to taxi on the step instead of taking off,
reduce the power as the seaplane is eased over onto the
step. More power is required to taxi with a heavy load.
However, 65 to 70 percent of maximum power is a
good starting point.
Taxiing on the step is a useful technique for covering
long distances on the water. Carefully reducing power
as the seaplane comes onto the step stops acceleration
so that the seaplane maintains a high speed across the
water, but remains well below flying speed. At these
speeds, the water rudders must be retracted to prevent
damage, but there is plenty of airflow for the air rudder.
With the seaplane on the step, gentle turns can be made
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