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4
Blade Performance Composite Propellers for Outboards and Sterndrives
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COMPROP propellers
are used as original equipment by Regal, Wellcraft, Four Winns and many
other quality boat builders. Why? Their testing shows 4 blade COMPROPs
accelerate quicker, run smoother, corner better and are faster than 3
blade aluminium propellers yet they cost less.
COMPROPs are very
durable. During soft bottom/low speed operating the composite material
resists dings, folds and blunting common to aluminium propellers. During
a high speed prop strike, the COMPROP blades are designed to break. This
absorbs much of the shock, reducing the likelihood of costly drive train
repairs (it costs much less to replace a COMPROP than a lower unit).
With prices lower
than aluminium and considerably lower than stainless steel, COMPROP simply
can not be beaten for low cost and performance.
COMPROPs are recommended
as a primary propeller up to 225 prop shaft horsepower or 3000 lb (1360kg)
boats. When replacing a propeller use one of a similar size and pitch
to achieve similar performance.
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| Question
and Answers |
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Q
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Is
COMPROP a primary prop or spare? |
A
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COMPROPs
are full-time , primary propellers. Many boat companies such a Regal, Wellcraft
and Four Winns have used COMPROPs as standard equipment. Basically,
if a boater is satisfied with aluminium performance, they will be happy
with COMPROP. If a boater is more demanding and wants the extra performance
of a stainless steel propeller (and doesn't mind the lower unit risk and
price, a COMPROP would be good choice for a backup. |
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Q
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What
are the best applications for a COMPROP? |
A
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All
types of family and fishing boats from 20 to 225 prop shaft horsepower. |
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Q
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How
does it perform? |
A
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Very
well. Similar to an aluminium propeller. The four blade series COMPROPs
have shown in tests by boat builders and major boating magazines to be at
least as fast as top-notch aluminium propellers. In most tests, they were
faster. Boaters will find the four blade COMPROPs also accelerate
quicker, corner much better, and are very smooth at all speeds. |
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Q
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What
is it made of? |
A
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A
high-tech composite material similar in strength to some aluminium alloys.
The actual composition of COMPROP is a trade secret. |
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Q
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How
tough is it? |
A
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Tougher
than aluminium in most cases. COMPROPs are extremely tough in low
speed/soft bottom conditions. If a boater is routinely digging up sand,
mud,gravel, etc., while at low speed or trolling in shallow waters, the
leading edge geometry will become scratched, but will not fold or blunt
like aluminium propellers. If continually dragged through the mud or sand
day after day, the COMPROP will gradually wear away the outer diameter.
The will not affect the performance significantly unless taken to extreme.
Aluminium propellers cannot withstand this type of environment. It is much
too severe. They must be repaired regularly. On the other hand, while travelling
at a high speed, if a boater strikes a stump or other underwater object
and has a severe prop strike, strong enough to break an aluminium blade,
the COMPROP blades are designed to break away to reduce the stress
to the lower unit. In this instance, a COMPROP coasts less than expensive
repairs to the drive train. |
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Q
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Are
4 blades better than 3? |
A
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Yes
- for most applications. Increasing the number of blades improves static
thrust (acceleration) abilities. It also improves cornering and fuel efficiency
while reducing vibration. If top speed is the highest priority, the fewest
number of blades is desirable. (Fewer blades means less parasitic drag at
top speed. Miss Budweiser, the ultimate hydroplane, uses a two bladed propeller,
but she gets a running start.) COMPROP four blade designs run just
as fast as three bladed aluminium propellers. Keep in mind adding blades
increases manufacturing costs in metal propellers. Most aluminium propellers
have three blades because it offers a good compromise between performance
and cost. COMPROP have the advantage due to the manufacturing method, many
secondary operations are eliminated. Allowing COMPROP 4 blade propellers
to be offered at prices less than 3 blade aluminium propellers. |
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Q
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I have a 3 blade 19" pitch propeller.
Which 4 blade is correct? |
A
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It is a simple 3 to 4 blade conversion. COMPROPs are labeled with
pitches similar to 3 blade aluminium propellers. If your boat uses a 19"
aluminium 3 blade propeller, use a 19" COMPROP. If we do not offer
a 19" pitch for your application, the 18" and 20" pitch 4
blade models will be very close in performance. |
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Q
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Are
COMPROPs more expensive? |
A
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When
in a soft bottom/shallow water environment, the leading edge of an aluminium
propeller will scar badly and be in need of a repair frequently, the COMPROP
will not damage (as described previously). After a severe prop strike, an
aluminium propeller may or may not be repairable. Sometimes the damage is
too great and new propeller must be purchased. Aluminium propeller repair
costs vary significantly Generally there is a choice between one new aluminium
propeller plus two repairs, or three brand new COMPROPs. Keep in
mind after several repairs to an aluminium propeller, it becomes brittle
and hard to repair. Each repair may also detract from original performance.
In summary, aluminium propellers may be more costly to use due to the constant
need of repair in certain environments. If a severe prop strike situation
are common (i.e. new boat drivers or unpredictable water depths), costs
may be close, but COMPROP has two clear advantage: 1. Better drive
train protection; and 2. A new COMPROP will easily outperform a repaired
aluminium propeller. |
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Q
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Why
do some metal propellers have a rudder hub? |
A
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The
rubber hub in older metal propellers is intended to protect the drive train
from propeller vibration, and shift shock. Unfortunately, rubber hubs deteriorate
over time and often do not perform as intended. The newest aluminium propellers
use a replaceable, solid nylon hub. The COMPROP design and material
eliminate the need for rubber hubs altogether. |
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Q
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Do
the COMPROP blades flex? |
A
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All
propeller blades flex during use. Stainless Steel flexes the least; that's
why stainless propellers generally have the best top speed. COMPROPs
flex about the same amount as an aluminium propeller; that is why performance
is similar. |
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Q
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Are
there limitations? |
A
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COMPROP
recommends a limit of 225 propeller shaft horsepower and a hull size of
21 feet (6.4m) and/or 3000 lbs (1360 kg). If the application is a twin,
larger limits apply. COMPROP designs are optimized with these limitations
in mind. If you choose to exceed these limits, performance may be compromised
and warranties are voided. |
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Acceptance
It is a challenge to lead the change from traditional metal propellers to
composite propellers. This is similar to Fibreglass replacing wood in new
boats during the 1950s. Fibreglass was a new material that; lowered cost,
maintained or improved performance and provided benefits the traditional
material couldn't match. There was initial reluctance, then acceptance.
It's true, history repeats itself. |
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| Please contact us for further
information on COMPROP or browse the COMPROP website |
C.E.& A. Co.
Pty Ltd.
5 Schenker Drive, Royal Park.
South Australia. 5014
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Ph. (08) 8240 0777
Fax. (08) 8240 0711 |
Int Ph. +618
8240 0777
Int Fax. +618 8240 0711 |
www.comprop.com |
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| ceaco@ceaco.com.au
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Information on this web page is extracted from the the
manufacturers literature and is displayed with their permission
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