PROP PICKING
How to make the right connection By Bruce W. Smith
Of all things club members can do
to their bassboats there’s not a single item that makes more of
a difference in overall performance than using the right prop.
It affects holeshot, top speed, engine rpm, bow rise, stern
lift, chine walking, porposing, stability, turning, backing,
fuel economy and rough-water handling.
Put another way, the prop affects every movement a boat makes
over the water.
But “right” doesn’t always mean one specific
prop. Like the tires on your tow rig, there can be several style
props that could come into play depending on the conditions—and
what you place the most importance on at the time.
Testing various props is the only way to see which one or ones
provide the performance and handling you feel works best for
your boat/engine setup.
For instance, let’s make handling a priority for a moment.
The number of blades on a prop makes a huge difference in the
way a bassboat—or any other planning-style boat—handles. The
more blades in the water, the better the engine’s power connects
and the more stable the boat becomes.
That’s why the bigger prop manufacturers offer three-, four-,
and five-blade models. Some even offer special six-blade models.
BLADE BASICS
The number of blades on a prop is a balance in
trade-offs. The more blades a prop has, the smoother it runs and
the better it bites. The downside is the more blades, the
greater the water resistance, reducing the boat/outboard
package’s overall operating efficiency.
Five-blade props
provide the best low-end acceleration, rough water
stability, and low-speed planning.
In theory, the most
efficient propeller would be one with a single blade because it
would offer the least resistance as it screws its way through
the water. But trying to balance a single bladed prop is
impractical from a manufacturing standpoint. It would also be
almost uncontrollable.
Two-bladed props can be easily balanced, but poor handling
and other undesirable characteristics make then unsuited for
recreational boaters such as bass fishermen.
A three-bladed prop, however, solves those handling and
balance issues. That’s why they are almost standard fare on most
engine packages. Today’s stainless three-blades typically
provide very good overall performance, along with faster top
speeds than their four- and five-blade counterparts.
Three-bladed props are the most common found on performance
bassboats. But three-bladed designs may not be the best choice
for your boat or water conditions.
The
downside is they don’t bite as well during launch as props with
more blades, and when the water roughs up a three-blade prop
doesn’t keep the boat connected to the water as well as a prop
with more blades.
This is important for those club members who fish primarily
on the weekends at crowded lakes. Boat traffic kicks up chop
that comes from all directions and a fast-moving bassboat
crossing such water needs to have that engine as connected to
the water as possible to provide the best handling.
ROUGH
WATER PROPS
Four-bladed props are a better choice for boaters
who want faster bottom-end acceleration and better boat controls
while running a lot in choppy or rough water.
The reason is simple: Four-blades tend to place more blade
area in the water than a similar three-blade model, stabilizing
the boat. They also bite better in sharp turns and make
low-speed maneuvering around the docks easier than the typical
three-blade.
Four-blade props also allow the boat to hold
“plane” at slower boat speeds. You can also set an outboard a
little higher on the transom with a four-blade prop than when
running a three-blade, reducing drag on the lower unit.
Fast, light bassboats can
benefit from a four-bladed prop if top speed isn’t the end-all
requirement.
Step up to a five-bladed prop and the result is superb
low-end acceleration and ultra-smooth engine operation; so
smooth you’ll wonder why five-blade props aren’t standard.
They are a terrific prop choice for getting a tuber or
wakeboarder up, and making a boat stick to the water in the
roughest of conditions. A five-blade would, in theory, also
provide the best mid-range operating efficiency.
The downside
is they are the slowest in top-end and drop upper-end fuel
economy because they have the greatest water-resistance of the
multi-blade configurations.
CALMING EFFECT
Bass boats with
lots of power, or ones that are short and or light, can be a
handful to drive if the outboard is setup with a three-blade.
That’s the beauty of choosing a prop with either four-or five
blades; the right number of blades makes a big difference in
calming down a “squirrelly” boat.
Replacing the three-blade prop with a four-blade stabilizes a
boat faster and better than downing two Tylenol for a bad
headache.
A four-blade prop is a good combination for those who run 16-
to 17-foot bassboats—be they jons or conventional mod-Vs. The
extra blade (or two if you decide to go with a five-blade style)
smoothes out the engine, calms the feeling at the helm, and
really connects the outboard to the water.
A four- or five-blade prop has a similar calming effect on
tiller-steers.
TWO-PROP CHOICE
Picking the right prop really depends on what you want from
your boat. If top speed is the only thing that matters, stick
with a three-blade.
If overall handling and efficiency is more your style, or you
fish tournaments where there’s a lot of late-afternoon boat
traffic and wind kicking up, a four-blade will make your time
behind the helm a lot more comfortable.
When the utility of a
bassboat switches from fishing platform to family pleasure, a
five-blade brings everything together nicely. A five-blade makes
the boat very easy to drive and very stable.
Of course the
ideal prop “setup” would be to have two stainless props
available to swap out as the conditions require for your
particular boat.
A great combo is a three-blade for those nice days when you
don’t mind sacrificing a little handling performance for that
extra couple miles-per-hour on the top-end, and a four-blade to
use when the weather and water conditions preclude running
flat-out.
Don’t have the money to buy a new prop? Ask around
the next bass club meeting to see if someone is doing some
changing of their own. If they are, their “old” prop just might
be the right one to compliment the one you are already using.
A Matter of Pitch
Keep in mind that when switching from one prop style to another
“pitch” needs to change accordingly. In general, stepping up in
number of blades requires stepping down one-inch in pitch.
For example, if your engine setup is dialed-in running a
three-blade prop with a 25-inch pitch and you want to switch to
a four-blade style, you should start with a 24-inch-pitch
four-blade. Likewise, if you switch from a three-blade to a
five-blade, drop two-inches in pitch.
These are only starting points for proper pitch; every prop
performs a little different. Try before you buy.
And when you are selecting a prop, choose the one with the pitch
that allows the engine to run up within a couple hundred rpm’s
of the engine’s peak operating range at full-throttle. Doing so
should give your boat the best all-around performance—from
holeshot to WOT. — Bruce W. Smith
Stainless vs. Aluminum
The performance of a prop depends on how well it makes its way
through the water. In other words, the thinner and sharper the
blades, and the less those blades flex, the better the prop
works.
Along that same train of thought, the material a prop is made
from makes as big difference in overall performance as the
number of blades.
That’s why if you are serious about making your bassboat perform
better—be it just improving fuel economy or all-around
performance—a stainless steel prop is the only option.
Stainless prop blades flex far less than aluminum, providing
better bite as the prop spins through the water; stainless
blades can be made thinner and sharper than aluminum so they are
more efficient; stainless steel is much more durable than
aluminum; and stainless can be shaped to provide better
performance characteristics than aluminum.
Although a stainless steel prop costs at least twice as much as
an aluminum version, the difference in overall handling and
performance far offsets any price factor. — Bruce W. Smith
