But how important is this? Isn't
each propeller of the same pitch the same? The
answer is no. Not only are props of the same
pitch different, but according to Prop Scan there
can be a difference in each blade. These differences
in manufacturing tolerances can cause a variety
of prop problems including vibration, tip erosion,
cavitation, general poor performance, and bad
fuel economy. Add to that, a prop hit and you
really have a headache. The imbalance of props
can and will destroy struts, shafts, and in extreme
cases the engine itself. Add twin engines to
the equation, and you can have twice the problem.
At a recent show, the folks from Prop
Scan used their software technology to demonstrate
problems with a stock production prop. Not only
did we find a difference in the pitch that was
stamped on the prop, but also in each of the blades.
When questioned if this was just a bad prop, they
answered that some props are better than other
but that most of new props they have measured have
some variance. In many cases Prop Scan stated this
manufacturing tolerance may not cause a problem,
but there are exceptions.
The best way to explain these variances
is to take a look at the tires on your car or truck.
They are all round and they roll down the road,
but each tire must be fine-tuned, it's called balancing.
We all know how unpleasant an out of balance tire
can be. It's an analogy but the same theory applies
How does Prop Scan work? First the
prop is mounted onto a fixture or table. The table
includes a rotating beam with a precise optical
sensor that includes a scribing wheel. As the blades
are rotated, the sensor and the wheel record the
deviations in the blade from the original design.
Information on the design and specifications are
loaded into the system's computer. Using information
supplied by the skipper about the engine's required
RPM and performance, the Prop Scan software converts
this data into line and bar graphs. Using this
data and the data supplied by the manufacturer
and the skipper, the software gives the operator
a visual indication of the current and the desired
pitch across the arc of each blade.
Although this is a simplified explanation
of the process, you can be assured that if there
is a problem with your prop, Prop Scan will find
it and enable the technician to correct it. After
the computers find the deficiencies in your prop,
the prop will have to be hammered into the proper
surface configuration. This process is truly a
marriage between old and new technology.
The man behind this remarkable technology
is Australian, Terry Ryan. Terry has combined his
years of knowledge of propeller design and their
physical properties, with his knowledge of programming
to develop the Prop Scan process and system. His
developments became so well respected throughout
the power boating community that the Royal Australian
Navy took notice. One thing led to another and
they are now using this technology and now the
Canadian and USA Navies use the system.
If Its Good for the Navy.
Now that we know Uncle Sam uses the
Prop Scan system, what about us recreational boaters?
This technology is readily available to anyone
since Mr. Ryan has set up training schools which
train technicians to use the Prop Scan system.
Throughout the US there are now 19 Prop Scan repair
stations to service our needs. What can we expect
from having our props inspected and massaged using
the Prop Scan system? The benefits are remarkable
and include less vibration, increased fuel savings,
less wear and tear on shafts, struts and bearings,
and in some cases a 50% increase in your vessel's
We spoke with a number of skippers
that have utilized this system and they all rave
about the results. The most common comment is that
they were not aware that the vessels could be so
smooth, vibration free and the increase in speed
was an unexpected benefit. All this from a man
with a vision, critical knowledge, and a desire
to make every prop as efficient as possible. Our
hats are off to Mr. Ryan.
For more information on this remarkable
Propeller Solutions, Inc.