| Most boats are designed to plane at a particular speed and weight
distribution. However, as weight increases (due to additional fuel, passengers, or gear)
and/or speed decreases, the stern settles down creating an inefficient, untrimmed
condition. As the boat pushes forward, it creates a "hill of water." In this
bow-high position visibility is limited and the hull bottom is pounded. In addition, due
to significant hull drag and extreme prop angle, fuel economy is poor. Properly sized
Bennett Trim Tabs enable your boat to overcome this "hill" and plane at speeds
slower than designed planing speed.
As the helm control is pressed, the stern rises, lowering the bow. Without touching the
throttle, speed increases and optimum attitude is achieved regardless of speed or weight
distribution.
Bennett Trim Tabs reposition the boat's bow to cut through the water reducing pounding,
drag, and engine laboring. Repositioning the bow creates greater visibility which
increases safety. Reduced pounding means greater comfort. Less drag and engine laboring
translate into increased performance, greater speed, and reduced fuel consumption.
With all the advantages and efficiencies created, Bennett Trim Tabs virtually pay for
themselves.
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Without Trim
Tabs |
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With Trim
Tabs |
THE PRINCIPLE OF BENNETT
TRIM TABS
Bennett Trim Tabs are two independent, stainless steel, adjustable
afterplanes attached to the bottom edge of the transom. As the helm control is pressed,
the trim tabs move into position.
Water-force on the trim tab surface creates upward pressure, thereby raising the stern and
lowering the bow. The principle is simple. The results are impressive.
THE BENNETT
ADVANTAGES
Performance
Increase Speed ? Reduce Pounding ? Correct Listing ?
Eliminate Porpoising ? Offset Prop Torque
Efficiency
Reduce Fuel Consumption ? Reduce Engine Laboring ? Eliminate
Squatting
Safety
Improve Visibility ? Reduce Wake ? Improve Handling ? Reduce
Hull Stress
How to Use Trim Tabs
GETTING STARTED
The key to obtaining optimal results from trim tabs is to operate them
in short ?bursts? and let the boat react before making another adjustment. The
amount of time between corrections is influenced by the size of the trim tabs and the
boat?s speed. This will help avoid overtrimming or ending up with one tab too far
down when correcting lateral trim. You will quickly become acquainted with a boat?s
particular traits.
TAKE OFF 
Properly sized trim tabs can significantly reduce the
time needed to get up on plane. They also allow a boat to keep its bow down and stay on
plane at lower speeds. As the throttle is advanced the stern of the boat begins to squat,
lifting the bow. As the boat accelerates, push the bow down position of the helm control
in short bursts. The boat reacts by the stern lifting, the bow coming down, speed
increasing, and reduced engine laboring. If you over do it and deflect the tabs too far
the boat will end up overtrimmed. When over trimmed, the steering becomes ?over
sensitive? and wants to pull off course to port or starboard. If this occurs, operate
the control ?bow up" until the desired attitude is established.
CORRECTING A LISTING CONDITION 
As a result of uneven weight distribution, prop torque or wind, a boat
runs with a list. Deep "V" hulls are particularly vulnerable to this condition.
Running with a list is uncomfortable, as well as unsafe. Bennett Trim Tabs operate
independently for effective list correction. To correct for list, lower the trim tab
on the side of the boat that you are listing to. This will bring the boat level.
TRIM TABS AND
POWER TRIM
It is a common misconception that if a boat has power
trim on the outboard or outdrive it does not need trim tabs. Power trim can be used to
adjust the boat's attitude, but it is highly inefficient. A propeller is designed to
force the boat forward. When trimming the boat with the prop, the prop must not only push
the boat forward but raise the stern as well. In this situation, prop slippage is greatly
increased thereby wasting RPM's. Power trim cannot correct listing, and is ineffective at
slower speeds. Bennett Trim Tabs, in combination with power trim, enable both the
hull and prop to be trimmed independently. The trim tabs trim the hull, while the power
trim adjusts the prop. The result is optimum performance and efficiency not attainable by
the use of power trim alone.
To achieve maximum performance, first adjust the trim
tabs to achieve the desired running attitude. Next, use the power trim to position the
propeller thrust parallel to the water flow. If necessary, re-adjust the trim tabs to fine
tune the attitude. By observing the boat?s speed and engine RPM's the best
combination of trim tabs and power trim will be apparent. Trim tab angle indicators and a
power trim angle indicator are particularly useful in duplicating effective settings.
 
TRIMMING TO SEA CONDITIONS
When running into a head sea you want to trim the bow down so the sharp forward sections
of the boat do their work cleaving the waves. This provides the most comfortable ride and
minimizes stress on the boat (and passengers). In a following sea the tabs should be fully
retracted for maximum steering response.
CORRECTION OF PORPOISING
Operate the tabs in very short bursts of about half a second. Continue until porpoising
subsides. The objective is to have only a very slight amount of tab deflection, just the
amount needed to cure the up and down motion of the bow.

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