PROPWASH
March 2015
11
NAMBA at AMA
By Dennis Hoover
District 19 Model Boater
In January, the anual Academy of
Model Aeronautics show was held at
the Ontario Convention Center in
Ontario, California. The NAMBA
District 19 booth was set up and run
by Dennis Hoover and Joe Monohan.
Hobbyists come to the booth for
information on model boating and the
insurance that is needed to operate
their model boats.
Representation at the expo is
essential for public outreach and
education. This picture to the right is a
perfect example of such outreach. Joe
Monohan is explaining to prospective
model boaters how to set up a hydro.
Being able to see these boats up close,
in person and having the opportunity
to speak with an experienced model
boater is important in being able to
continue to spread interest in the
hobby.
At the 2015 AMA Show, Leon
Embry (picture to the right) took first
place in the Best of Scale model
competition. His superior craftsman-
ship and attention to detail earned him
a $400 cash prize. His Monterey
Fishing Boat is fully functional and
fully automated.
Spring Safety Corner
By Lohring Miller
NAMBA Safety Chairman
Next are two props from Bob Austin.
They both started as Prop Shop 6518
props that have a nominal diameter of
2.56” (65 mm) and a nominal pitch of
4.6” (117 mm). The first is labeled
6518 #3. The diameter is 2.50” (63.5
mm). The cup is uniform along the
trailing edge at 7.2“ (183 mm). The
pitch starts at 5.18” (132 mm) and
quickly decreases to a constant
4.0” (102 mm).
The second is labeled 6518 430. Its
diameter is 2.52” (64 mm) with a
uniform cup of 7.1” (180 mm). The
pitch starts at 5.0” (127 mm) and
decreases to a constant pitch of 3.6” (91
mm).
These props are very similar with
slight pitch and diameter differences.
The first compensates for more pitch
with a slightly smaller diameter and less
cup. Which is faster? It will depend in
your boat and engine.
All the props discussed above have a
degree of progressive pitch. The Octura
prop has a gradual cup that could be
considered a continuation of the
increasing pitch from the leading edge
to the trailing edge along the blade. The
Prop Shop props have a more
conventional cupped trailing edge like
the cup picture shows. Both work very
well.
These are just the basic principles of
propeller preparation. Only experience
will make you an expert. Listen and
watch what the experts do. Measure
their props. See if you can use the same
principles to make your boat faster.
6518 on the Pitch Gauge
Pick up all those tools and put them where you can find them
when you need them
(Continued on page 12)
