Boat Operation Continued
High speed turning. Since less of the airboat hull
is in contact with the water surface you may find
that the boat is actually faster in the turns than on
the straights. You truly end up “flying” the airboat
through the turns. This is what sets an airboat
apart from any other form of boating. Turns at
wide open throttle (WOT) should be made with
the utmost care as you can detach the boat from
the water surface completely and go airborne, flip,
and land up-side-down! With the recommended
power system and two cell 7.4V battery your
WaterBoard™ will be on the ragged edge of flight
through high speed turns and may flip if a gust of
wind catches it. With an 11.1V battery you’ll have
to be incredibly vigilant when pushing the
performance through turns. Be prepared (you did
bring recovery items to the pond today right?) and
build speed only as you become comfortable with
the boats operation.
In the event of a capsize. IMMEDIATELY cut
throttle to the electric motor. Running the motor
only briefly while submerged may over-current the
electronics and cause a failure.
Retrieve boat. As water has filled the motor
mount hold boat inverted to allow water to drain
from motor mount then right boat, clear prop, and
run fan to clear out water and check function of
electronics. You may, at this time, wish to remove
the electronics hatch lid to inspect his area for
moisture.
Fresh water will have no effect on the motor and
the recommended servos have proven to be
remarkably water resistant. Thus a capsize event
that’s quickly resolved will not typically result in
loss or damage to electrical equipment. Also note
that salt water is highly corrosive to the fittings
and electronics in this boat.
This boat has not
been designed to run in salt or brackish
waters.
Battery tips and estimating run times. LiPo
batteries are easily damaged if over-discharged
and, unlike the familiar NiCd and NiMH cells,
require specialized care when charging and
discharging. If unfamiliar with the use of LiPo
b a t t e r i e s p l e a s e c o n t a c t y o u r b a t t e r y
manufacturer for instructions regarding proper
care.
A unique feature of LiPo chemistry is the small
voltage drop between the charged and
discharged state. A 7.4 volt LiPo battery is
considered 100% discharged when the battery
reads 6.0V and 100% charged when the battery
reads 8.4V. Compare this to the typical 6 or 7 cell
NiCd or NiMH pack of equivalent pack voltage
which can typically be run to an almost zero
voltage condition and it becomes clear that LiPo
powered electronics are not going to go behave
as though the batteries are running dead. Thus it
becomes tough to discern when/if it’s time to
return to shore and “refuel”. Add to this the fact
that your electronic speed control (ESC) has been
designed to protect your pack from over
discharge by turning off the fan motor when the
battery pack voltage reaches ~6.2V and it
becomes clear that you may find yourself
stranded with a dead pack while in the water.
The way to prevent being stranded is to strive to
use only 3/4 of the rated pack capacity during a
normal session leaving you with ample reserves
to get back to shore. Without a watt meter or
some other onboard monitoring device this can
prove tricky. However, I’ve found the following
method to work quite well: Start with 5-8 min
sessions, return to shore and check your battery
voltage, if you find the battery voltage to be at or
slightly over the packs nominal voltage (7.4V for a
two cell pack) then it’s a good bet that you’ve only
consumed 1/2 of your available power and can
most likely extend your session by 1/2 of the time
spent on the water during your initial session. If
you find the pack voltage to be well under nominal
you should consider not extending your session
times between charge cycles.
Run times will be influenced by how heavy
handed you are with throttle, the prop pitch and
diameter run, wind conditions, battery capacity,
battery “C” discharge rates, and ambient
temperature. In general we’ve found the
suggested power-system with 2100mah 7.4V
battery to provide a solid 15 min of leisurely run
time or a solid 8 minutes of “racing”.
End of session procedures. Upon returning to
shore remember to
keep clear of the prop!
Back out the screws for the electronics access
hatch lid just far enough so that the lid may be
lifted and removed. Disconnect your battery.
Turn off your radio. Wipe dry the outside of the
boat and remove any water that may have found
it’s way inside the hatch. Leave the hatch cover
off of boat when in storage so that gasket will
remain spongy. Store boat in a cool dry
environment.
© 2010 Stevens AeroModel all rights reserved. V2.0 (11.10.2014)
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