22
boat can become an instant winner just by using the right propeller.
As a rule of thumb, non-lifting propellers are best-suited for your
tunnel hull. Some lifting propellers can work but typically need to
be “re-worked” to work well on a Tunnel Hull. For the best overall
performance stick with a low lift propeller like the AquaCraft
GrimRacer 40X53 or AquaCraft GrimRacer 40X52/3. Testing your
propeller is best done with a stopwatch. The most important reading
is the time the boat takes to go from buoy one (1) to buoy three (3)
IMPBA and buoys one (1) through fi ve (5) NAMBA. Second most
important time to capture is over all lap speed. Your boat may sound
or look faster with a prop change, but don’t let that fool you. Course
timing is the best way to determine what if any changes your prop
change as made.
Rudder Defl ection:
Your TS3 needs very little rudder defl ection to
make it around a corner. Obviously your boat will turn tighter with
more rudder defl ection but the truth is this can upset the boat in the
corners. It is best to have just enough rudder defl ection to make a
nice sweeping corner PLUS just a tad tighter. To set the amount of
rudder defl ection, run your boat on the race course and half throttle.
Adjust the steering dual rate until the boat makes a nice sweeping
corner a few feet off the buoys. Next: Run the boat at top speed
(remember to lift off the throttle just a little going into the corner)
and drive the course. Add in more dual rate until the boat runs the
course smooth and fast. Give a few more clicks on the dual rate
adjustment. The extra movement might be needed to get you out of
danger in the middle of a race.
TOP SPEED 3 BASIC SETUP PARAMETERS
.200" Center of the prop shaft
to the bottom of the sponsons
.5° Negative
Parallel to the transom
7.5" (27%) to 8.6" (31%)
from the back of the sponsons
AQUB9720 – 40X52/3
1-3/4" left
1-3/4" right
ENGINE
HEIGHT
PROPELLER
THRUST ANGLE
HINGE PIN
ANGLE
C.G.
RANGE
PROP
RUDDER
DEFLECTION
makes the boat run faster but at a greater risk of blowing the boat
off the water (fl ipping it over backwards). It also can cause loss of
steering in the corners if set too high. Lowering the shaft has the
opposite effect and makes the boat more stable but can slow the
boat considerably. It is also important to note that having the shaft
too low can cause the boat to stuff or tuck under going around the
corner. Setting the shaft (prop height) is a very important part of
tuning your boat. It is also good to note that even 1/16" higher or
lower can make or break a good running tunnel boat.
Propeller Shaft Angle:
Changing the propeller shaft angle causes
the bow of the boat to either run higher or lower depending on the
angle. What we are trying to accomplish by changing the shaft angle
is to loosen up the boat on the water to make it go as fast as possible
More positive (+) shaft angle lifts the bow, causing the boat’s tunnel
to capture more air, hence less drag and more speed. The risk of
having too much positive shaft angle is the possibility of blowing the
boat off the water. Too much negative (–) and the boat will run too
wet. Typical modern RC tunnel boats run with about 1/2° of negative
(–) shaft angle.
Hinge Pin Angle:
(shimming required) Not all outboard engine
mounting systems allow you to change the hinge pin angle
separately from the stub shaft angle. It is worth noting, however,
that outboard engines that do have a distinct advantage over the
ones that don’t. Let me explain. When the servo swings your engine
left or right, the stub shaft follows the arc that the hinge pin has set
for it. If you have a positive hinge pin angle your stub shaft swings in
a positive, neutral, positive motion ( + 0 + ). If your hinge pin angle is
set negative, your stub shaft swings in a negative, neutral, negative
motion ( – 0 – ). It’s important to note this as the more positive angle
the hinge is set at, the higher the bow raises in the corners and the
opposite regarding negative pin angle. These can be a huge tuning
advantage for the way you drive. To adjust the hinge pin angle you
must shim either the top or the bottom of the engine mount plate
from the transom.
You are going to want to avoid engine mounts that set the hinge
pin past the back of the sponsons. Having the pin in front of the
sponson we call under steer, and behind the back of the sponsons
over steer. The TS3 likes the pin in the under steer position.
Center Of Gravity (CG):
The center of gravity “balance” of your
boat is just as important as other adjustments you make. Adding
or removing weight from the front of the boat ultimately decides the
stability of the boat as it fl ies over the top of the water. The further
forward you have the CG, the more speed the hull can handle, but like
other adjustments to your boat comes with a price. As a model tunnel
boat operates the boat’s ride can become disrupted. Any “acting
forces” i.e. wind, waves, drag and or acceleration/deceleration can
cause the boat to lose its balance. A properly set CG gives you the
best overall balance regarding all those changing conditions.
Propeller:
First and foremost you need to balance or use a balanced
propeller. Not only will this provide the best performance but it is
necessary to avoid damaging your engine. You can learn more about
how to balance your propeller at
www.aquacraftmodels.com
The propeller is probably the most important aspect of how fast
your boat goes and/or how well it handles. A poor handing, slow
